Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0006457 protein folding	IBA GO_REF:0000033	ACCEPT	Summary: Hsp83/HSP90 is a well-established molecular chaperone whose primary biological role is protein folding. The IBA annotation is supported by strong phylogenetic evidence across multiple orthologs (PMID:10716925, UniProt function annotation). UniProt states Hsp83 is a "Molecular chaperone that promotes the maturation, structural maintenance and proper regulation of specific target proteins." Reason: Protein folding is the core biological process of HSP90 family chaperones. IBA is well-supported by orthologs and consistent with all functional literature on Hsp83. Supporting Evidence: PMID:10716925 a member of the highly conserved Hsp90 family including chaperones known to maintain the activity of many proteins file:DROME/Hsp83/Hsp83-deep-research-falcon.md Hsp83 is best understood as the cytosolic Hsp90 ATP-dependent chaperone that promotes late-stage folding/maturation, stabilization, and activation of diverse client proteins, especially those central to signaling and development
GO:0016887 ATP hydrolysis activity	IBA GO_REF:0000033	ACCEPT	Summary: Hsp83/HSP90 has intrinsic ATPase activity that is essential for its chaperone cycle. The UniProt record notes it "Undergoes a functional cycle that is linked to its ATPase activity." The IBA annotation is supported by phylogenetic inference from multiple HSP90 orthologs with experimentally characterized ATPase activity. Reason: ATP hydrolysis is a core enzymatic activity of the HSP90 family. The HATPase_c domain is well characterized structurally and the ATPase cycle drives the chaperone conformational changes. Consistent with IBA evidence across the HSP90 family. Supporting Evidence: PMID:29775584 the Hsp90 system (Hop, Hsp90, and p23) together render Ago2 into an open, active form file:DROME/Hsp83/Hsp83-deep-research-falcon.md Mechanistically, Hsp90 proteins are dimeric, undergoing an ATP-driven conformational cycle involving ATP binding/hydrolysis and large structural rearrangements that enable remodeling/maturation of clients
GO:0032991 protein-containing complex	IBA GO_REF:0000033	ACCEPT	Summary: HSP90 family members function as homodimers and form multi-protein complexes with co-chaperones (Hop, p23, Cdc37, Aha1) and client proteins. UniProt states Hsp83 is a "Homodimer" and describes multiple complexes including with Hop/piwi, sicily/ND-42, Dpit47/Hsp70aa, and Nup358. The IBA annotation to the generic protein-containing complex is correct but very general. Reason: HSP90 is known to form multiple protein complexes. While the term is generic, IBA annotations at this level are acceptable as they reflect the phylogenetic inference. More specific complex annotations (GO:0101031, GO:0034663) are captured elsewhere.
GO:0005886 plasma membrane	IBA GO_REF:0000033	ACCEPT	Summary: IBA annotation to plasma membrane is supported by phylogenetic inference from multiple HSP90 orthologs. Hsp83 was also detected at the plasma membrane by HDA (PMID:19317464). Hsp90 has an amphipathic helix that allows membrane interaction (PMID:30193096), which could explain plasma membrane localization. Reason: Plasma membrane localization is consistent with both the IBA evidence from orthologs and the independent HDA evidence from proteomics (PMID:19317464). The amphipathic helix-mediated membrane interaction described in PMID:30193096 provides a mechanistic basis. Supporting Evidence: PMID:30193096 Hsp90 also has the ability to directly interact with and deform membranes via an evolutionarily conserved amphipathic helix
GO:0005524 ATP binding	IBA GO_REF:0000033	ACCEPT	Summary: ATP binding is a fundamental property of HSP90 family members, mediated by the HATPase_c domain. UniProt lists multiple ATP binding residues (positions 39, 81, 100, 126, 385) and the keyword "ATP-binding." IBA annotation is well supported. Reason: ATP binding is intrinsic to the HSP90 ATPase domain. Structurally characterized across the family.
GO:0005829 cytosol	IBA GO_REF:0000033	ACCEPT	Summary: Cytosolic localization of HSP90 family members is well established. IBA annotation from multiple orthologs. Consistent with UniProt subcellular location annotation to "Cytoplasm" and multiple IDA/HDA annotations to cytoplasm in Drosophila. Reason: Cytosol is the primary localization for cytoplasmic HSP90 family members. IBA is well supported.
GO:0050821 protein stabilization	IBA GO_REF:0000033	ACCEPT	Summary: HSP90 chaperones stabilize client proteins, preventing their degradation. UniProt states Hsp83 "promotes the maturation, structural maintenance and proper regulation of specific target proteins." IBA from multiple orthologs. Loss of Hsp90 function leads to decreased levels of client proteins such as ND42 and NDUFS3 (PMID:23509070), directly demonstrating protein stabilization. Reason: Protein stabilization is a core function of HSP90 -- client proteins are destabilized and degraded when HSP90 is inhibited. Well supported by phylogenetic evidence and direct experimental data in Drosophila. Supporting Evidence: PMID:23509070 Both NDUFS3 and ND42 are severely down-regulated in sicily mutants, whereas other mitochondrial proteins, including Porin (Graham et al., 2010) and cytochrome c, are unaltered or slightly increased file:DROME/Hsp83/Hsp83-deep-research-falcon.md Hsp83 is best understood as the cytosolic Hsp90 ATP-dependent chaperone that promotes late-stage folding/maturation, stabilization, and activation of diverse client proteins, especially those central to signaling and development
GO:0034605 cellular response to heat	IBA GO_REF:0000033	ACCEPT	Summary: Hsp83 is a heat shock protein that is upregulated in response to heat stress. IBA from multiple orthologs. Consistent with IEP evidence from PMID:16595740 showing Hsp83 protein levels increase after heat shock. Name itself (Heat shock protein 83) reflects this function. Reason: Cellular response to heat is a defining characteristic of heat shock proteins. IBA supported by expression and functional data in Drosophila. Supporting Evidence: PMID:16595740 increases in the levels of Hsp83 and DnaJ-1 proteins but not in the inducible form of Hsp70 were detected by Western blot analysis
GO:0051082 unfolded protein binding	IBA GO_REF:0000033	MODIFY	Summary: GO:0051082 "unfolded protein binding" is proposed for obsoletion. HSP90 does not simply bind unfolded proteins like holdase chaperones; rather, it acts as an ATP-dependent foldase that binds near-native client proteins and assists their maturation through conformational change driven by ATP hydrolysis. The correct MF term is GO:0140662 "ATP-dependent protein folding chaperone." Reason: GO:0051082 is proposed for obsoletion and does not accurately describe the HSP90 mechanism. HSP90 does not primarily bind unfolded proteins; it binds near-native, partially folded client proteins and uses ATP hydrolysis to drive their maturation. The replacement term GO:0140662 "ATP-dependent protein folding chaperone" precisely captures the molecular function. Proposed replacements: ATP-dependent protein folding chaperone Supporting Evidence: PMID:29775584 the Hsp90 system is required to extend the dwell time of Ago2 in the open state, which must be transiently primed by the Hsp70 system
GO:0048471 perinuclear region of cytoplasm	IBA GO_REF:0000033	ACCEPT	Summary: IBA annotation to perinuclear region of cytoplasm is supported by phylogenetic inference from multiple orthologs. Also supported by direct experimental evidence in Drosophila (IDA, PMID:22902557) where Hsp83 was observed in perinuclear region via the piRNA pathway work with Shutdown (Shu). Reason: Consistent with IBA evidence and directly confirmed by IDA in Drosophila (PMID:22902557).
GO:0000166 nucleotide binding	IEA GO_REF:0000043	ACCEPT	Summary: IEA annotation from UniProtKB keyword mapping (KW-0547 "Nucleotide-binding"). Hsp83 is indeed an ATP-binding protein with a well-characterized nucleotide binding pocket. This is a broader parent term of ATP binding (GO:0005524) which is already annotated with IBA evidence. Reason: Correct but redundant with the more specific ATP binding annotation. IEA annotations at broader levels than IBA are acceptable.
GO:0005524 ATP binding	IEA GO_REF:0000120	ACCEPT	Summary: IEA annotation for ATP binding from combined automated methods (InterPro:IPR001404, InterPro:IPR019805, UniProtKB-KW:KW-0067). Correct and consistent with IBA annotation for the same term. Reason: Redundant with IBA annotation for the same GO term. Both are correct. Hsp83 has a well-characterized HATPase domain.
GO:0005737 cytoplasm	IEA GO_REF:0000044	ACCEPT	Summary: IEA annotation from UniProt subcellular location vocabulary mapping. UniProt annotates Hsp83 subcellular location as "Cytoplasm." Consistent with multiple IDA and HDA annotations for cytoplasm. Reason: Correct. Cytoplasmic localization is well established by multiple independent lines of evidence.
GO:0006457 protein folding	IEA GO_REF:0000002	ACCEPT	Summary: IEA annotation from InterPro domain mapping (IPR001404, IPR019805). Protein folding is the core biological process of HSP90 family. Consistent with IBA and other evidence. Reason: Correct. Redundant with IBA annotation. InterPro correctly maps the HSP90 domain to the protein folding process.
GO:0016887 ATP hydrolysis activity	IEA GO_REF:0000002	ACCEPT	Summary: IEA annotation from InterPro domain mapping (IPR001404). ATP hydrolysis is intrinsic to the HATPase domain of HSP90. Consistent with IBA. Reason: Correct. Redundant with IBA annotation. InterPro correctly maps the HSP90 HATPase domain to ATP hydrolysis activity.
GO:0051082 unfolded protein binding	IEA GO_REF:0000002	MODIFY	Summary: IEA annotation from InterPro domain mapping. GO:0051082 is proposed for obsoletion. HSP90 does not function as a holdase chaperone that binds unfolded proteins; it is an ATP-dependent foldase that acts on near-native client proteins. Reason: Same issue as the IBA annotation for this term. GO:0051082 is proposed for obsoletion and does not accurately represent the HSP90 mechanism. Should be replaced with GO:0140662 "ATP-dependent protein folding chaperone." Proposed replacements: ATP-dependent protein folding chaperone
GO:0101031 protein folding chaperone complex	IEA GO_REF:0000117	ACCEPT	Summary: IEA annotation from ARBA machine learning model (ARBA:ARBA00026483). HSP90 forms multiple chaperone complexes. Consistent with IDA evidence from PMID:33176138 for the same term. Reason: Correct. HSP90 is a core component of protein folding chaperone complexes. Consistent with direct experimental evidence in Drosophila.
GO:0140662 ATP-dependent protein folding chaperone	IEA GO_REF:0000002	ACCEPT	Summary: IEA annotation from InterPro domain mapping (IPR001404). GO:0140662 "ATP-dependent protein folding chaperone" is the correct molecular function term for HSP90, accurately capturing its ATP-dependent chaperone mechanism. This is the term that should replace GO:0051082 across all annotations. Reason: This is the most accurate MF term for HSP90 function. HSP90 binds client proteins and assists their folding/maturation through ATP hydrolysis-driven conformational changes. Supporting Evidence: PMID:29775584 the Hsp90 system is required to extend the dwell time of Ago2 in the open state
GO:0005515 protein binding	IPI PMID:22579285 Hsp90 globally targets paused RNA polymerase to regulate gen...	MARK AS OVER ANNOTATED	Summary: IPI annotation from IntAct based on physical interaction with Nelf-E (P92204). PMID:22579285 showed Hsp90 localizes to promoters and stabilizes the NELF complex to maintain RNA polymerase II pausing. While the interaction is real, "protein binding" is uninformative. Reason: The interaction with Nelf-E is likely reflecting Hsp83's chaperone activity on NELF complex stabilization. "Protein binding" is too generic and uninformative. The chaperone function is better captured by GO:0140662, and the biological outcome (gene expression regulation) is a downstream effect of chaperone activity. Supporting Evidence: PMID:22579285 Hsp90 maintains and optimizes RNA polymerase II pausing via stabilization of the negative elongation factor complex (NELF)
GO:0034663 endoplasmic reticulum chaperone complex	IPI PMID:22099462 XPORT-dependent transport of TRP and rhodopsin.	MARK AS OVER ANNOTATED	Summary: IPI annotation based on physical interaction evidence (PMID:22099462), with interactors FB:FBgn0038749 and FB:FBgn0289994. PMID:22099462 identifies XPORT as a chaperone for TRP and rhodopsin that interacts with Hsp90 in the ER/secretory pathway. Hsp83 is primarily a cytoplasmic chaperone, and ER localization would be atypical for the cytoplasmic HSP90 (as opposed to ER-resident GRP94/Hsp90B1). Reason: PMID:22099462 shows XPORT (a resident ER/secretory-pathway protein) interacts with Hsp90, but the IPI-based CC annotation to an ER chaperone complex over-interprets this transient interaction. Falcon deep research confirms Hsp83 is the sole CYTOSOLIC Hsp90-family chaperone in D. melanogaster and is primarily cytosolic; stable residence in an ER chaperone complex would be atypical for the cytoplasmic HSP90 (the ER-resident Hsp90 paralog is GRP94/ Hsp90B1, encoded separately by Gp93 in flies). The most parsimonious interpretation is a transient cytosolic-side interaction of Hsp83 with XPORT during client (TRP/Rh1) processing rather than bona fide membership of an ER chaperone complex. The chaperone activity itself is better captured by GO:0140662 and GO:0101031. Supporting Evidence: PMID:22099462 XPORT is a resident ER and secretory pathway protein that interacts with TRP and Rh1, as well as with Hsp27 and Hsp90 file:DROME/Hsp83/Hsp83-deep-research-falcon.md Hsp83 is the sole cytosolic Hsp90-family chaperone in D. melanogaster and functions as an ATP-dependent molecular chaperone that promotes late-stage folding, maturation, stabilization, and activation of signaling clients.
GO:0005739 mitochondrion	ISS GO_REF:0000024	KEEP AS NON CORE	Summary: ISS annotation transferred from human HSP90AA1 (P07900). A minor pool of HSP90 has been reported in mitochondria in mammalian cells. Hsp83 interacts with Sicily for chaperoning ND42 before mitochondrial import (PMID:23509070), but this occurs in the cytoplasm. Mitochondrial localization of the fly protein itself is not directly demonstrated. Reason: Mitochondrial localization is plausible based on mammalian ortholog data but not directly demonstrated in Drosophila. The cytoplasmic chaperoning of mitochondrial proteins (PMID:23509070) does not require Hsp83 itself to localize to mitochondria. Supporting Evidence: PMID:23509070 Sicily preprotein interacts with cytosolic Hsp90 to chaperone the CI subunit, ND42, before mitochondrial import
GO:0097753 membrane bending	IDA PMID:30193096 Hsp90 Mediates Membrane Deformation and Exosome Release.	KEEP AS NON CORE	Summary: IDA annotation based on direct demonstration in PMID:30193096 that Hsp90 can directly interact with and deform membranes via an evolutionarily conserved amphipathic helix. This is a non-chaperone function structurally separated from the protein folding activity. Reason: Membrane bending is a genuine, experimentally validated function of Hsp90 mediated by its amphipathic helix. However, it is a non-canonical function distinct from the core chaperone activity and therefore non-core. The paper explicitly states they "structurally separated the Hsp90 membrane-deforming function from its well-characterized chaperone activity." Supporting Evidence: PMID:30193096 Hsp90 also has the ability to directly interact with and deform membranes via an evolutionarily conserved amphipathic helix PMID:30193096 we structurally separated the Hsp90 membrane-deforming function from its well-characterized chaperone activity
GO:0098866 multivesicular body fusion to apical plasma membrane	IMP PMID:30193096 Hsp90 Mediates Membrane Deformation and Exosome Release.	KEEP AS NON CORE	Summary: IMP annotation from PMID:30193096. The amphipathic helix of Hsp90 promotes the fusion of multivesicular bodies (MVBs) with the plasma membrane, enabling exosome release. Mutations and drugs that stabilize the open Hsp90 dimer expose the helix and allow MVB fusion. Reason: This is a genuine but non-core function mediated by the non-chaperone membrane-deforming activity of Hsp90. Not a typical chaperone function. Supporting Evidence: PMID:30193096 this amphipathic helix allows exosome release by promoting the fusion of multivesicular bodies (MVBs) with the plasma membrane
GO:0070922 RISC complex assembly	IGI PMID:29775584 Conformational Activation of Argonaute by Distinct yet Coord...	ACCEPT	Summary: IGI annotation from PMID:29775584 with genetic interactors FB:FBgn0037728 and FB:FBgn0266599. The paper demonstrates that Hsp70/Hsp90 chaperone machinery is required for loading small RNAs into Argonaute, a key step in RISC assembly. The Hsp90 system captures and stabilizes the open, active form of Ago2. Reason: RISC complex assembly is a well-characterized function of the Hsp90 chaperone system. Hsp90 is required for conformational activation of Argonaute to enable small RNA loading. This is a specific manifestation of its core chaperone function on a defined client protein complex. Supporting Evidence: PMID:29775584 Loading of small RNAs into Argonaute, the core protein in RNA silencing, requires the Hsp70/Hsp90 chaperone machinery PMID:29775584 the Hsp90 system is required to extend the dwell time of Ago2 in the open state
GO:0070922 RISC complex assembly	IPI PMID:33176138 Modulation of Ago2 Loading by Cyclophilin 40 Endows a Unique...	ACCEPT	Summary: IPI annotation from PMID:33176138 with interactors FB:FBgn0036020, FB:FBgn0087035, and FB:FBgn0262739. PMID:33176138 identifies Cyclophilin 40 as a testis-specialized Hsp90 co-chaperone that modulates Ago2-RISC formation. Cyp40 interacts with Ago2 through Hsp90 and promotes the build-up of Ago2-bound miRNAs. Reason: Consistent with the IGI evidence from PMID:29775584 and with the known role of HSP90 in Argonaute maturation and RISC assembly. Additional IPI evidence strengthens the annotation. Supporting Evidence: PMID:33176138 Cyp40 interacts with duplex-incorporating Ago2 through Hsp90 in vitro and selectively promotes the build-up of Ago2-bound miRNAs
GO:0005515 protein binding	IPI PMID:31907206 Drosophila Morgana is an Hsp90-interacting protein with a di...	MARK AS OVER ANNOTATED	Summary: IPI annotation from UniProt based on interaction with Morgana/CHORD (Q9VCC0). PMID:31907206 showed that Morgana co-purifies with the Hsp90-R2TP-TTT supercomplex. This is a typical co-chaperone interaction. Reason: "Protein binding" is uninformative. The interaction with Morgana reflects Hsp83's role as part of the Hsp90-R2TP-TTT chaperone supercomplex. This is better captured by the chaperone complex annotations (GO:0101031) and the ATP-dependent protein folding chaperone MF term (GO:0140662). Supporting Evidence: PMID:31907206 Mora localises to mitotic spindles and co-purifies with the Hsp90-R2TP-TTT supercomplex and with additional well-known Hsp90 co-chaperones
GO:0016887 ATP hydrolysis activity	ISS GO_REF:0000024	ACCEPT	Summary: ISS annotation transferred from human HSP90AA1 (P07900). ATP hydrolysis is well established for HSP90 family members. Consistent with IBA evidence for the same term. Reason: Correct. Redundant with IBA. ATP hydrolysis is a core function of the HSP90 family.
GO:0101031 protein folding chaperone complex	IDA PMID:33176138 Modulation of Ago2 Loading by Cyclophilin 40 Endows a Unique...	ACCEPT	Summary: IDA annotation from PMID:33176138 directly demonstrating Hsp83 as part of a protein folding chaperone complex. PMID:33176138 shows Hsp90 machinery acts as chaperone complex for Ago2 loading during RISC assembly. HSP90 forms complexes with co-chaperones (Hop, p23, Cdc37, Cyp40, etc.) to constitute chaperone machinery. Reason: HSP90 is a core component of chaperone complexes. IDA evidence directly confirms this in Drosophila. Consistent with UniProt subunit annotations describing multiple Hsp83-containing complexes. Supporting Evidence: PMID:33176138 In gene silencing, Hsp90 chaperone machinery assists Argonaute (Ago) binding and unwinding of silencing small RNA (sRNA) duplexes
GO:0005515 protein binding	IPI PMID:23509070 The C8ORF38 homologue Sicily is a cytosolic chaperone for a ...	MARK AS OVER ANNOTATED	Summary: IPI annotation from UniProt based on interaction with Sicily (P91929) and ND-42/NDUFA10 (Q9VYS5). PMID:23509070 showed Sicily is a cytosolic chaperone for a mitochondrial Complex I subunit, and Hsp83 forms a complex with Sicily and ND42. Hsp90 binds to Sicily directly and coimmunoprecipitates ND42 only when Sicily is coexpressed. Reason: "Protein binding" is uninformative. The interaction with Sicily reflects Hsp83's chaperone function in chaperoning ND42 before mitochondrial import. Better captured by the ATP-dependent protein folding chaperone MF term (GO:0140662) and the protein stabilization BP term (GO:0050821). Supporting Evidence: PMID:23509070 Hsp90 binds to Sicily in an in vitro co-IP assay
GO:0002052 positive regulation of neuroblast proliferation	IMP PMID:30245208 Hsp83/Hsp90 Physically Associates with Insulin Receptor to P...	KEEP AS NON CORE	Summary: IMP annotation from PMID:30245208. Hsp83 is both necessary and sufficient for neural stem cell reactivation by promoting the activation of InR pathway in larval brains. This is a downstream pleiotropic effect of Hsp83 chaperone function on signaling clients. Reason: This is a downstream developmental phenotype of Hsp83 function, likely mediated through its role in insulin receptor signaling (same paper provides insulin receptor binding annotation). Non-core pleiotropic effect. Supporting Evidence: PMID:30245208 Hsp83 is both necessary and sufficient for NSC reactivation by promoting the activation of InR pathway in larval brains in the presence of dietary amino acids
GO:0005158 insulin receptor binding	IDA PMID:30245208 Hsp83/Hsp90 Physically Associates with Insulin Receptor to P...	KEEP AS NON CORE	Summary: IDA annotation from PMID:30245208 demonstrating direct binding of Hsp83 to the insulin receptor. Both Hsp83 and its co-chaperone Cdc37 physically associate with InR. HSP90 is known to chaperone receptor tyrosine kinases in other systems. This likely reflects HSP90's general role in chaperoning kinase clients. Reason: Insulin receptor binding is consistent with HSP90's well-known role as a kinase chaperone, but it represents a specific client interaction rather than a core molecular function. The core function is the ATP-dependent protein folding chaperone activity. Supporting Evidence: PMID:30245208 Both Hsp83 and its co-chaperone Cdc37 physically associate with InR
GO:0046628 positive regulation of insulin receptor signaling pathway	IGI PMID:30245208 Hsp83/Hsp90 Physically Associates with Insulin Receptor to P...	KEEP AS NON CORE	Summary: IGI annotation from PMID:30245208 with genetic interactor FB:FBgn0283499. Hsp83 positively regulates insulin receptor signaling, consistent with its role in chaperoning the insulin receptor. Reason: Downstream pleiotropic effect of Hsp83 chaperone function on insulin signaling. Non-core but experimentally supported. Supporting Evidence: PMID:30245208 Hsp83 is both necessary and sufficient for NSC reactivation by promoting the activation of InR pathway in larval brains in the presence of dietary amino acids
GO:0005737 cytoplasm	HDA PMID:26896675 A genome-wide resource for the analysis of protein localisat...	ACCEPT	Summary: HDA annotation from a genome-wide protein localization study (PMID:26896675) using GFP-tagged fosmid transgenes in Drosophila. Cytoplasmic localization is consistent with all other evidence. Reason: Cytoplasm is the primary localization for Hsp83. Confirmed by multiple independent methods. Supporting Evidence: PMID:26896675 A genome-wide resource for the analysis of protein localisation in Drosophila
GO:0030911 TPR domain binding	IPI PMID:27979731 Nucleoporin Nup358 facilitates nuclear import of Methoprene-...	ACCEPT	Summary: IPI annotation from PMID:27979731 based on interaction of Hsp83 with the TPR domain of Nup358. The C-terminal MEEVD motif of HSP90 is a well-characterized TPR repeat-binding motif (UniProt: "The TPR repeat-binding motif mediates interaction with TPR repeat-containing proteins"). The interaction with Nup358 TPR domain facilitates nuclear import of Met, the juvenile hormone receptor. Reason: TPR domain binding is a core molecular function of HSP90 family members, mediated by the conserved C-terminal MEEVD motif. This is how HSP90 interacts with many co-chaperones (Hop, CHIP, Tom70, etc.) and other TPR-containing proteins. Supporting Evidence: PMID:27979731 a tetratricopeptide repeat (TPR) domain at the N-terminal end of Nup358 interacts with Hsp83 and is indispensable for Met nuclear localization file:DROME/Hsp83/Hsp83-deep-research-falcon.md Key named regulators include Cdc37 (kinase client recruitment), p23, and Aha1, as well as TPR-domain proteins such as Hop that bind the conserved MEEVD C-terminal motif typical of cytosolic Hsp90s
GO:0006457 protein folding	ISS GO_REF:0000024	ACCEPT	Summary: ISS annotation transferred from yeast HSP82 (P15108). Protein folding is well established for HSP90 family. Consistent with IBA and IEA evidence. Reason: Correct. Redundant with IBA and IEA. Protein folding is the core biological process.
GO:0034605 cellular response to heat	ISS GO_REF:0000024	ACCEPT	Summary: ISS annotation transferred from yeast HSP82 (P15108). Cellular response to heat is well established for heat shock proteins. Consistent with IBA evidence. Reason: Correct. Redundant with IBA. Heat shock response is a defining feature of HSP90 family.
GO:0043248 proteasome assembly	IDA PMID:15946124 Zn2+-induced reversible dissociation of subunit Rpn10/p54 of...	KEEP AS NON CORE	Summary: IDA annotation from PMID:15946124. Hsp82 (Hsp83) was identified by mass spectrometry as the main Rpn10/p54-interacting protein after Zn2+-induced proteasome disassembly, suggesting a role in reassembly of the 26S proteasome. Reason: The evidence shows Hsp83 interacts with Rpn10 after proteasome disassembly, suggesting a role in reassembly. This is consistent with HSP90's general chaperone function applied to proteasome components, but represents a specific client relationship rather than a core function. Supporting Evidence: PMID:15946124 Hsp82 (heat-shock protein 82) has been identified by MS as the main Rpn10/p54-interacting protein, suggesting its role in the reassembly of the 26 S proteasome after Zn2+ removal
GO:0005737 cytoplasm	HDA PMID:24292889 Ube3a, the E3 ubiquitin ligase causing Angelman syndrome and...	ACCEPT	Summary: HDA annotation from PMID:24292889 (Ube3a proteasomal shuttle Rpn10 study). Cytoplasmic localization detected as part of a high-throughput study. Consistent with other evidence. Reason: Cytoplasm localization is well established. Additional HDA evidence. Supporting Evidence: PMID:24292889 Overexpression of these proteins leads to an enhanced accumulation of ubiquitinated proteins, further supporting the biochemical evidence of interaction obtained in neuronal cells
GO:0005886 plasma membrane	HDA PMID:19317464 Mapping organelle proteins and protein complexes in Drosophi...	ACCEPT	Summary: HDA annotation from PMID:19317464 (LOPIT subcellular proteomics study in Drosophila embryos). Plasma membrane localization detected in this systematic study. Consistent with IBA annotation and the amphipathic helix-mediated membrane interaction (PMID:30193096). Reason: Plasma membrane localization supported by independent proteomics evidence and consistent with IBA and the membrane-deforming function. Supporting Evidence: PMID:19317464 we apply LOPIT, a mass-spectrometry based technique that simultaneously maps proteins to specific subcellular compartments, to Drosophila embryos
GO:0051082 unfolded protein binding	IDA PMID:18344983 NAD synthase NMNAT acts as a chaperone to protect against ne...	MODIFY	Summary: IDA annotation from PMID:18344983. This paper is primarily about NMNAT as a chaperone, not about Hsp83 directly. The paper shows that NMNAT "displays chaperone function both in biochemical assays and cultured cells" and compares it to Hsp70. Hsp83 is mentioned as a control or comparison. Regardless, GO:0051082 is proposed for obsoletion and the term does not correctly describe HSP90 function. HSP90 is an ATP-dependent foldase, not a holdase. Reason: GO:0051082 is proposed for obsoletion. The evidence in PMID:18344983 is primarily about NMNAT chaperone function, with Hsp83 as a comparison. The correct term for Hsp83 molecular function is GO:0140662 "ATP-dependent protein folding chaperone." Proposed replacements: ATP-dependent protein folding chaperone Supporting Evidence: PMID:18344983 NMNAT displays chaperone function both in biochemical assays and cultured cells, and it shares significant structural similarity with known chaperones
GO:0008285 negative regulation of cell population proliferation	IMP PMID:24086162 The molecular chaperone Hsp90 is required for cell cycle exi...	KEEP AS NON CORE	Summary: IMP annotation from PMID:24086162. Hsp83 mutation results in increased E2F-dependent transcription and ectopic cell proliferation in pupal tissues, demonstrating that Hsp83 is required for proper cell cycle exit. The paper proposes Cdh1/Fzr (APC/C activating subunit) is a client of Hsp83. Thus Hsp83 indirectly promotes cell cycle exit by chaperoning APC/C components. Reason: This is a downstream phenotypic consequence of Hsp83 chaperone function on cell cycle regulators (APC/C components). The paper proposes "Cdh1/Fzr is a client protein of Hsp83." This is a pleiotropic effect of the core chaperone function, not a core function itself. Supporting Evidence: PMID:24086162 Mutation of Hsp83, the Drosophila homolog of mammalian Hsp90, results in increased E2F-dependent transcription and ectopic cell proliferation in pupal tissues at a time when neighboring wild-type cells are postmitotic PMID:24086162 we propose that Cdh1/Fzr is a client protein of Hsp83 file:DROME/Hsp83/Hsp83-deep-research-falcon.md In Hsp83(6-55) mutant clones, E2F-dependent transcription increases and cells show ectopic S phase and mitosis after neighboring cells have exited the cell cycle
GO:0048471 perinuclear region of cytoplasm	IDA PMID:22902557 The cochaperone shutdown defines a group of biogenesis facto...	ACCEPT	Summary: IDA annotation from PMID:22902557. This paper studies the cochaperone Shutdown and piRNA biogenesis. Using a genomic GFP-tagged Hsp83 construct, the authors show that Hsp83 is enriched in a peri-nuclear rim in wild-type nurse cells, potentially reflecting nuage accumulation. Hsp83 colocalizes with unloaded AGO3 in cytoplasmic foci when piRNA biogenesis is disrupted. Reason: Perinuclear region localization is directly demonstrated by IDA using GFP-tagged Hsp83 and is consistent with IBA evidence and the known role of Hsp83 in piRNA biogenesis in germline nuage. Supporting Evidence: PMID:22902557 Hsp83 was enriched in a peri-nuclear rim, potentially reflecting nuage accumulation
GO:0005705 polytene chromosome interband	IDA PMID:19144915 Trithorax requires Hsp90 for maintenance of active chromatin...	ACCEPT	Summary: IDA annotation from PMID:19144915. This paper shows a direct molecular interaction between Hsp90 and Trithorax, and that Hsp90 cooperates with Trx at chromatin for maintaining the active expression state of targets like Hox genes. Polytene chromosome interband localization is consistent with the chromatin-binding function of Hsp90. Reason: PMID:19144915 demonstrates Hsp90 interacts with Trithorax at chromatin to maintain active gene expression. Polytene chromosome interband localization is consistent with this chromatin-associated function and with the finding from PMID:22579285 that Hsp90 localizes to promoters. Supporting Evidence: PMID:19144915 Hsp90 cooperates with Trx at chromatin for maintaining the active expression state of targets like the Hox genes
GO:0005737 cytoplasm	IDA PMID:19144915 Trithorax requires Hsp90 for maintenance of active chromatin...	ACCEPT	Summary: IDA annotation from PMID:19144915. Cytoplasmic localization is consistent with all other evidence. Reason: Cytoplasm localization is independently confirmed by many other studies. This annotation is redundant but correct. Supporting Evidence: PMID:19144915 Molecular chaperone heat-shock protein 90 kDa (Hsp90) is known to facilitate the conformational maturation of a diverse range of proteins involved in different signal transduction pathways during development
GO:0009631 cold acclimation	IEP PMID:16313561 Cold hardening and transcriptional change in Drosophila mela...	KEEP AS NON CORE	Summary: IEP annotation from PMID:16313561. Microarray analysis showed Hsp83 transcript was differentially expressed after cold hardening treatment (0 C for 2 h followed by recovery). The evidence is expression-based only (IEP), and does not demonstrate a direct functional role. Reason: Based solely on expression evidence (IEP). Transcript upregulation during cold hardening does not prove a direct role in cold acclimation. However, Hsp83 may contribute to protein homeostasis under cold stress. Keeping as non-core due to indirect evidence. Supporting Evidence: PMID:16313561 stress proteins, including Hsp23, Hsp26, Hsp83 and Frost as well as membrane-associated proteins may contribute to the cold hardening response
GO:0009408 response to heat	IEP PMID:16595740 Thermoprotection of synaptic transmission in a Drosophila he...	ACCEPT	Summary: IEP annotation from PMID:16595740. Hsp83 protein levels were shown to increase after heat shock by Western blot analysis, even in a heat shock factor mutant (hsf4). As a constitutively expressed heat shock protein, Hsp83 upregulation during heat stress provides thermoprotection at synapses. Reason: While IEP is weaker evidence, the response to heat is fundamental to heat shock proteins. The name "Heat shock protein 83" itself reflects this. The more specific term "cellular response to heat" (GO:0034605) is also annotated with IBA and ISS evidence. Falcon deep research adds an important nuance: Hsp83 is largely a constitutive proteostasis factor and is NOT transcriptionally induced in every proteotoxic stress state (e.g., in a 2023 larval fat body study Hsp83 and Gp93 did not change despite induction of Hsp70/Hsp40-class genes). The response-to-heat annotation remains valid (protein levels do rise after heat shock per PMID:16595740), but it reflects a partially constitutive, context- dependent thermoprotective role rather than a universally inducible response. Supporting Evidence: PMID:16595740 the compensatory upregulation of constitutively expressed Hsps, in the absence of the synthesis of the major inducible Hsp, Hsp70, could still provide substantial thermoprotection file:DROME/Hsp83/Hsp83-deep-research-falcon.md A 2023 Nature Communications study in Drosophila larval fat body found that Nacα reduction activates a heat shock response, with upregulation of Hsp70/Hsp40 class genes and oxidative stress markers, but Hsp83 (and another Hsp90-family gene Gp93) did not change in that context (qRT-PCR, n=4 batches)
GO:0005737 cytoplasm	IDA PMID:19101615 The molecular chaperone Hsp90 is a component of the cap-bind...	ACCEPT	Summary: IDA annotation from PMID:19101615. Hsp90 and Cup co-localize in the cytoplasm of developing germ-line cells within the germarium. Reason: Cytoplasmic localization directly demonstrated during oogenesis. Consistent with all other cytoplasm annotations. Supporting Evidence: PMID:19101615 Hsp90 and Cup co-localize in the cytoplasm of the developing germ-line cells within the germarium
GO:0048477 oogenesis	IGI PMID:19101615 The molecular chaperone Hsp90 is a component of the cap-bind...	KEEP AS NON CORE	Summary: IGI annotation from PMID:19101615 with genetic interactor Cup (FB:FBgn0000392). Lowering Hsp90 activity enhances oogenesis alterations linked to diverse cup mutant alleles, demonstrating a genetic interaction in oogenesis. Hsp90 is a component of the cap-binding complex and interacts with the translational repressor Cup during oogenesis. Reason: Oogenesis involvement is a pleiotropic consequence of Hsp83 chaperone function during development. The paper shows Hsp90 participates in translational regulation during oogenesis via the cap-binding complex. This is a downstream developmental role, not a core function. Supporting Evidence: PMID:19101615 lowering Hsp90 activity enhances the oogenesis alterations linked to diverse cup mutant alleles file:DROME/Hsp83/Hsp83-deep-research-falcon.md Hsp83 also contributes to female fertility, oogenesis, and maternal RNA regulation. It interacts with the translational regulator Cup during oogenesis, localizes maternal transcripts, and affects nanos mRNA localization, linking Hsp83 to anterior–posterior patterning in embryos.
GO:0019094 pole plasm mRNA localization	IMP PMID:17565952 The molecular chaperone Hsp90 is required for mRNA localizat...	KEEP AS NON CORE	Summary: IMP annotation from PMID:17565952. Genetic approaches show that Hsp83/Hsp90 is a localization factor for nanos and pgc mRNAs. When Hsp90 function is partially compromised, nanos and pgc mRNA localization is disrupted while other pole plasm components are unaffected. The mechanism appears to involve Hsp90 chaperoning LKB1 kinase (for pgc) and other partners (for nos). Reason: This is a specific developmental role of Hsp83 in mRNA localization during embryogenesis, likely mediated through its chaperone function on LKB1 kinase and other clients. Non-core pleiotropic effect. Supporting Evidence: PMID:17565952 the Hsp90 chaperone (encoded by Hsp83 in Drosophila) is a localization factor for two mRNAs, nanos and pgc PMID:17565952 levels of the LKB1 kinase are reduced in Hsp83 mutant egg chambers file:DROME/Hsp83/Hsp83-deep-research-falcon.md It interacts with the translational regulator Cup during oogenesis, localizes maternal transcripts, and affects nanos mRNA localization, linking Hsp83 to anterior–posterior patterning in embryos.
GO:0005813 centrosome	IDA PMID:10716925 Hsp90 is a core centrosomal component and is required at dif...	ACCEPT	Summary: IDA annotation from PMID:10716925. Mass spectrometry analysis of immunoisolated Drosophila centrosomes identified Hsp83. The association persists after microtubule depolymerizing drug treatment, indicating Hsp90 is a core centrosomal component. Reason: Directly demonstrated by mass spectrometry of purified centrosomes and confirmed to be a core centrosomal component that persists after microtubule depolymerization. Supporting Evidence: PMID:10716925 a fraction of the total Hsp90 pool is localized at the centrosome throughout the cell cycle PMID:10716925 This association between Hsp90 and the centrosome can be observed in purified centrosomes and after treatment with microtubule depolymerizing drugs, two criteria normally used to define core centrosomal components
GO:0006457 protein folding	TAS PMID:10716925 Hsp90 is a core centrosomal component and is required at dif...	ACCEPT	Summary: TAS annotation from PMID:10716925 which describes Hsp83 as "a member of the highly conserved Hsp90 family including chaperones known to maintain the activity of many proteins." The protein folding function is stated as established fact in the publication. Reason: Correct. Protein folding is the core function. Redundant with IBA, IEA, and ISS evidence. Supporting Evidence: PMID:10716925 a member of the highly conserved Hsp90 family including chaperones known to maintain the activity of many proteins
GO:0007098 centrosome cycle	IMP PMID:10716925 Hsp90 is a core centrosomal component and is required at dif...	KEEP AS NON CORE	Summary: IMP annotation from PMID:10716925. Disruption of Hsp90 function by mutations in Hsp83 or geldanamycin treatment results in abnormal centrosome separation and maturation, aberrant spindles, and impaired chromosome segregation. Reason: Centrosome cycle involvement is a downstream consequence of Hsp83 chaperone function on centrosome client proteins. Hsp90 is required for proper centrosome function, but this is a pleiotropic effect of its core chaperone activity. Supporting Evidence: PMID:10716925 Disruption of Hsp90 function by mutations in the Drosophila gene or treatment of mammalian cells with the Hsp90 inhibitor geldanamycin, results in abnormal centrosome separation and maturation, aberrant spindles and impaired chromosome segregation
GO:0045187 regulation of circadian sleep/wake cycle, sleep	IMP PMID:12015603 Stress response genes protect against lethal effects of slee...	KEEP AS NON CORE	Summary: IMP annotation from PMID:12015603. Flies carrying a mutation for Hsp83 showed exaggerated homeostatic sleep response and died after sleep deprivation, demonstrating that Hsp83 plays a protective role in sleep homeostasis. Reason: Sleep regulation is a pleiotropic downstream effect. Hsp83 mutants show exaggerated homeostatic response to sleep deprivation, but this likely reflects a general stress-protective role rather than a direct sleep-regulatory function. Supporting Evidence: PMID:12015603 flies carrying a mutation for the heat-shock protein Hsp83 (Hsp83(08445)) showed exaggerated homeostatic response and died after sleep deprivation
GO:0045187 regulation of circadian sleep/wake cycle, sleep	TAS PMID:12486704 Perchance to dream: solving the mystery of sleep through gen...	KEEP AS NON CORE	Summary: TAS annotation from PMID:12486704. This is a review article discussing sleep research in Drosophila and mouse, referencing the genetic approaches that identified Hsp83 mutants with sleep phenotypes. Reason: Consistent with the IMP annotation from PMID:12015603 for the same term. Sleep regulation is a non-core pleiotropic effect. Supporting Evidence: PMID:12486704 studies in both the mouse and fly have begun to reveal tantalizing suggestions about the underlying principles that regulate sleep homeostasis

Core Functions

The primary molecular function of Hsp83. As a member of the HSP90 family, Hsp83 binds near-native client proteins and uses its intrinsic ATPase activity to drive conformational changes that promote client maturation, activation, and stabilization. Known clients include kinases (insulin receptor, LKB1), transcription factors, Argonaute, APC/C components (Cdh1/Fzr), and centrosomal proteins.

Molecular Function:

ATP-dependent protein folding chaperone

Directly Involved In:

protein folding protein stabilization cellular response to heat RISC complex assembly

Cellular Locations:

cytosol

In Complex:

protein folding chaperone complex

Supporting Evidence:

PMID:29775584
the Hsp90 system is required to extend the dwell time of Ago2 in the open state
PMID:23509070
Sicily preprotein interacts with cytosolic Hsp90 to chaperone the CI subunit, ND42, before mitochondrial import

References

GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms

GO_REF:0000024

Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity

GO_REF:0000033

Annotation inferences using phylogenetic trees

GO_REF:0000043

Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping

GO_REF:0000044

Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt

GO_REF:0000117

Electronic Gene Ontology annotations created by ARBA machine learning models

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

PMID:10716925

Hsp90 is a core centrosomal component and is required at different stages of the centrosome cycle in Drosophila and vertebrates.

Hsp83 identified by mass spectrometry in purified Drosophila centrosomes

"One of the proteins identified is Hsp83, a member of the highly conserved Hsp90 family including chaperones known to maintain the activity of many proteins"
A fraction of total Hsp90 pool is localized at the centrosome throughout the cell cycle

"a fraction of the total Hsp90 pool is localized at the centrosome throughout the cell cycle at different stages of development in Drosophila and vertebrates"
Disruption of Hsp90 function causes abnormal centrosome separation and maturation

"Disruption of Hsp90 function by mutations in the Drosophila gene or treatment of mammalian cells with the Hsp90 inhibitor geldanamycin, results in abnormal centrosome separation and maturation, aberrant spindles and impaired chromosome segregation"

PMID:12015603

Stress response genes protect against lethal effects of sleep deprivation in Drosophila.

Hsp83 mutants show exaggerated homeostatic sleep response and die after sleep deprivation

"flies carrying a mutation for the heat-shock protein Hsp83 (Hsp83(08445)) showed exaggerated homeostatic response and died after sleep deprivation"
Heat-shock genes protect against lethal effects of sleep deprivation

"activating heat-shock genes before sleep deprivation rescued cyc(01) flies from its lethal effects"

PMID:12486704

Perchance to dream: solving the mystery of sleep through genetic analysis.

PMID:15946124

Zn2+-induced reversible dissociation of subunit Rpn10/p54 of the Drosophila 26 S proteasome.

Hsp82 identified by MS as the main Rpn10/p54-interacting protein after proteasome disassembly

"Hsp82 (heat-shock protein 82) has been identified by MS as the main Rpn10/p54-interacting protein, suggesting its role in the reassembly of the 26 S proteasome after Zn2+ removal"
Suggests Hsp83 role in reassembly of 26S proteasome

"removal of Zn2+ is followed by reassociation of subunit Rpn10/p54 to the RP, reassembly of the 26 S proteasome and resumption of the peptidase activity"

PMID:16313561

Cold hardening and transcriptional change in Drosophila melanogaster.

Hsp83 transcript upregulated after cold hardening treatment

"stress proteins, including Hsp23, Hsp26, Hsp83 and Frost as well as membrane-associated proteins may contribute to the cold hardening response"

PMID:16595740

Thermoprotection of synaptic transmission in a Drosophila heat shock factor mutant is accompanied by increased expression of Hsp83 and DnaJ-1.

Hsp83 protein levels increase after heat shock even in hsf4 mutants

"increases in the levels of Hsp83 and DnaJ-1 proteins but not in the inducible form of Hsp70 were detected by Western blot analysis"
Compensatory upregulation of constitutive Hsps provides thermoprotection

"the compensatory upregulation of constitutively expressed Hsps, in the absence of the synthesis of the major inducible Hsp, Hsp70, could still provide substantial thermoprotection"

PMID:17565952

The molecular chaperone Hsp90 is required for mRNA localization in Drosophila melanogaster embryos.

Hsp83/Hsp90 is a localization factor for nanos and pgc mRNAs

"the Hsp90 chaperone (encoded by Hsp83 in Drosophila) is a localization factor for two mRNAs, nanos and pgc"
LKB1 kinase levels reduced in Hsp83 mutant egg chambers

"levels of the LKB1 kinase are reduced in Hsp83 mutant egg chambers"

PMID:18344983

NAD synthase NMNAT acts as a chaperone to protect against neurodegeneration.

NMNAT displays chaperone function similar to heat-shock proteins

"NMNAT displays chaperone function both in biochemical assays and cultured cells, and it shares significant structural similarity with known chaperones"
Hsp83 used as comparison/control in chaperone assays

"it is upregulated in the brain upon overexpression of poly-glutamine expanded protein and recruited with the chaperone Hsp70 into protein aggregates"

PMID:19101615

The molecular chaperone Hsp90 is a component of the cap-binding complex and interacts with the translational repressor Cup during Drosophila oogenesis.

Hsp90 isolated as component of cap-binding complex

"isolated the product of the Hsp83 gene, the evolutionarily conserved chaperone Hsp90, as a specific component of the cap-binding complex"
Hsp90 interacts with translational repressor Cup

"Hsp90 interacts in vitro with the translational repressor Cup"
Hsp83 and cup interact genetically in oogenesis

"lowering Hsp90 activity enhances the oogenesis alterations linked to diverse cup mutant alleles"
Hsp90 and Cup co-localize in cytoplasm of germline cells

"Hsp90 and Cup co-localize in the cytoplasm of the developing germ-line cells within the germarium"

PMID:19144915

Trithorax requires Hsp90 for maintenance of active chromatin at sites of gene expression.

Hsp90 interacts directly with Trithorax and cooperates at chromatin for maintaining active expression

"Hsp90 cooperates with Trx at chromatin for maintaining the active expression state of targets like the Hox genes"
Pharmacological inhibition of Hsp90 results in degradation of Trx and down-regulation of homeotic gene expression

"Pharmacological inhibition of Hsp90 results in degradation of Trx and a concomitant down-regulation of homeotic gene expression"

PMID:19317464

Mapping organelle proteins and protein complexes in Drosophila melanogaster.

LOPIT proteomics maps Hsp83 subcellular distribution in Drosophila embryos

"we apply LOPIT, a mass-spectrometry based technique that simultaneously maps proteins to specific subcellular compartments, to Drosophila embryos"

PMID:22099462

XPORT-dependent transport of TRP and rhodopsin.

XPORT interacts with TRP, Rh1, Hsp27, and Hsp90 as part of ER chaperone function

"XPORT is a resident ER and secretory pathway protein that interacts with TRP and Rh1, as well as with Hsp27 and Hsp90"
XPORT promotes targeting of TRP to the membrane in Drosophila S2 cells

"XPORT promotes the targeting of TRP to the membrane in Drosophila S2 cells"

PMID:22579285

Hsp90 globally targets paused RNA polymerase to regulate gene expression in response to environmental stimuli.

Hsp90 localizes to promoters of many genes

"It localizes near promoters of many coding and noncoding genes including microRNAs"
Hsp90 stabilizes NELF complex to maintain RNA Pol II pausing

"Hsp90 maintains and optimizes RNA polymerase II pausing via stabilization of the negative elongation factor complex (NELF)"
Hsp90 inhibition leads to upregulation of target genes

"Inhibition of Hsp90 leads to upregulation of target genes"

PMID:22902557

The cochaperone shutdown defines a group of biogenesis factors essential for all piRNA populations in Drosophila.

Hsp83 interacts with cochaperone Shutdown (Shu)

"unloaded AGO3 that localizes to cytoplasmic foci interacts with Hsp83"
Required for piRNA biogenesis

"our genetic and cell biological data point toward an important role for the Hsp83 machinery in piRNA biogenesis"
Hsp83 enriched in peri-nuclear rim in wild-type nurse cells

"Hsp83 was enriched in a peri-nuclear rim, potentially reflecting nuage accumulation"

PMID:23509070

The C8ORF38 homologue Sicily is a cytosolic chaperone for a mitochondrial complex I subunit.

Hsp83 forms complex with Sicily and ND42 for mitochondrial protein chaperoning

"Sicily preprotein interacts with cytosolic Hsp90 to chaperone the CI subunit, ND42, before mitochondrial import"
Hsp90 binds to Sicily directly and coimmunoprecipitates ND42 only when Sicily is coexpressed

"Hsp90 binds to Sicily in an in vitro co-IP assay"
Loss of Hsp90 leads to decreased levels of Sicily and CI subunits in vivo

"flies expressing Hsp90 RNAi #1 exhibit severely decreased levels of Sicily, ND42, and NDUFS3 compared with controls"

PMID:24086162

The molecular chaperone Hsp90 is required for cell cycle exit in Drosophila melanogaster.

Hsp83 mutation causes increased E2F transcription and ectopic cell proliferation

"Mutation of Hsp83, the Drosophila homolog of mammalian Hsp90, results in increased E2F-dependent transcription and ectopic cell proliferation in pupal tissues at a time when neighboring wild-type cells are postmitotic"
APC/C targets accumulate in Hsp83 mutant cells

"these Hsp83 mutant cells have increased Cyclin/Cdk activity and accumulate proteins normally targeted for proteolysis by the anaphase-promoting complex/cyclosome (APC/C)"
Cdh1/Fzr proposed as an Hsp83 client protein

"we propose that Cdh1/Fzr is a client protein of Hsp83"

PMID:24292889

Ube3a, the E3 ubiquitin ligase causing Angelman syndrome and linked to autism, regulates protein homeostasis through the proteasomal shuttle Rpn10.

PMID:26896675

A genome-wide resource for the analysis of protein localisation in Drosophila.

Genome-wide GFP tagging resource for protein localization

"a genome-wide fosmid library of 10000 GFP-tagged clones, comprising tagged genes and most of their regulatory information"

PMID:27979731

Nucleoporin Nup358 facilitates nuclear import of Methoprene-tolerant (Met) in an importin β- and Hsp83-dependent manner.

Nup358 TPR domain interacts with Hsp83

"a tetratricopeptide repeat (TPR) domain at the N-terminal end of Nup358 interacts with Hsp83 and is indispensable for Met nuclear localization"
Interaction required for nuclear import of Met (JH receptor)

"Nup358 facilitates JH-induced Met nuclear transport in a manner dependent on importin β and Hsp83"

PMID:29775584

Conformational Activation of Argonaute by Distinct yet Coordinated Actions of the Hsp70 and Hsp90 Chaperone Systems.

Hsp90 system captures and stabilizes the open active form of Ago2

"the Hsp90 system is required to extend the dwell time of Ago2 in the open state"
Required for small RNA loading into Argonaute

"Loading of small RNAs into Argonaute, the core protein in RNA silencing, requires the Hsp70/Hsp90 chaperone machinery"
Hsp70 system expands structural ensembles, Hsp90 stabilizes active form

"the Hsp70 system expands the structural ensembles of Ago2 and the Hsp90 system captures and stabilizes the active form"

PMID:30193096

Hsp90 Mediates Membrane Deformation and Exosome Release.

Hsp90 deforms membranes via amphipathic helix

"Hsp90 also has the ability to directly interact with and deform membranes via an evolutionarily conserved amphipathic helix"
Membrane function structurally separated from chaperone activity

"we structurally separated the Hsp90 membrane-deforming function from its well-characterized chaperone activity"
Open Hsp90 dimer exposes helix for MVB fusion

"mutations and drugs that stabilize the open Hsp90 dimer expose the helix and allow MVB fusion"

PMID:30245208

Hsp83/Hsp90 Physically Associates with Insulin Receptor to Promote Neural Stem Cell Reactivation.

Hsp83 is both necessary and sufficient for NSC reactivation by promoting activation of InR pathway

"Hsp83 is both necessary and sufficient for NSC reactivation by promoting the activation of InR pathway in larval brains in the presence of dietary amino acids"
Both Hsp83 and its co-chaperone Cdc37 physically associate with InR

"Both Hsp83 and its co-chaperone Cdc37 physically associate with InR"

PMID:31907206

Drosophila Morgana is an Hsp90-interacting protein with a direct role in microtubule polymerisation.

Morgana co-purifies with Hsp90-R2TP-TTT supercomplex

"Mora localises to mitotic spindles and co-purifies with the Hsp90-R2TP-TTT supercomplex and with additional well-known Hsp90 co-chaperones"
Mora localises to mitotic spindles

"Drosophila Mora localises to mitotic spindles and co-purifies with the Hsp90-R2TP-TTT supercomplex"

PMID:33176138

Modulation of Ago2 Loading by Cyclophilin 40 Endows a Unique Repertoire of Functional miRNAs during Sperm Maturation in Drosophila.

Cyp40 interacts with duplex-incorporating Ago2 through Hsp90 in vitro

"Cyp40 interacts with duplex-incorporating Ago2 through Hsp90 in vitro and selectively promotes the build-up of Ago2-bound miRNAs"
Identifies RISC-regulatory roles for Hsp90 machinery

"these results identify RISC-regulatory roles for Hsp90 machinery"

PMID:21186352

Drosophila Piwi functions in Hsp90-mediated suppression of phenotypic variation.

Hsp83 interacts with Hop and Piwi

"we isolated a protein complex composed of Hsp90, Piwi and Hop, the Hsp70/Hsp90 organizing protein homolog"
Required for piRNA biogenesis and transposon suppression

"Hsp90 and Hop regulate the piRNA pathway through Piwi to mediate canalization"
Mediates developmental robustness via epigenetic silencing

"epigenetic silencing of the expression of existing genetic variants and the suppression of transposon-induced new genetic variation as two major mechanisms underlying piRNA pathway-mediated canalization"

file:DROME/Hsp83/Hsp83-deep-research-falcon.md

Falcon deep research report on Hsp83 (Drosophila melanogaster)

Hsp83 is the cytosolic Hsp90 ATP-dependent chaperone that operates via an ATP-driven conformational cycle to promote late-stage folding, maturation, stabilization, and activation of diverse signaling/developmental client proteins.

"Hsp83 is best understood as the **cytosolic Hsp90 ATP-dependent chaperone** that promotes **late-stage folding/maturation, stabilization, and activation** of diverse client proteins, especially those central to signaling and development (prodromou2022advancestowardsunderstanding pages 1-3, oostenhawle2023organismalrolesof pages 1-3). Mechanistically, Hsp90 proteins are **dimeric**, undergoing an **ATP-driven conformational cycle** involving **ATP binding/hydrolysis** and large structural rearrangements that enable remodeling/maturation of clients"
The Hsp83/Hsp90 chaperone cycle is regulated by co-chaperones including Cdc37 (kinase client recruitment), p23, Aha1, and TPR-domain proteins such as Hop that bind the conserved C-terminal MEEVD motif of cytosolic Hsp90.

"Key named regulators include **Cdc37** (kinase client recruitment), **p23**, and **Aha1**, as well as **TPR-domain** proteins such as **Hop** that bind the conserved **MEEVD** C-terminal motif typical of cytosolic Hsp90s"
Hsp83/Hsp90 is required to activate the ecdysone receptor heterodimer EcR/USP; a purified Hsp83-Hsc70-Hop-Hip-FKBP52-p23 multichaperone complex reconstitutes functional EcR/USP DNA binding in vitro, and activation requires ATP hydrolysis and Mg2+. This is a steroid-hormone-receptor maturation role analogous to mammalian Hsp90 chaperoning of nuclear receptors.

"A key Drosophila primary study demonstrated that the **ecdysone receptor heterodimer EcR/USP requires an Hsp83/Hsp90-containing multichaperone complex for activation**. Purified components—Hsp83 (Hsp90), Hsc70, Hop, Hip, FKBP52, and p23—were sufficient to reconstitute functional EcR/USP DNA binding in vitro, and activation required **ATP hydrolysis and Mg2+**"
Hsp83 facilitates juvenile hormone signaling by promoting nuclear import of the JH receptor Methoprene-tolerant (Met). Hsp83 physically interacts with Met, JH enhances this interaction, and Hsp83 loss of function reduces JH-induced Met nuclear import and JH-responsive Kr-h1 transcription.

"In Drosophila juvenile hormone signaling, Hsp83 physically interacts with the JH receptor **Methoprene-tolerant (Met)**, and JH increases the Met–Hsp83 interaction. Hsp83 loss-of-function attenuates JH binding and reduces JH-induced **nuclear import** of Met, decreasing JH-responsive transcription of **Kr-h1**"
Hsp83 promotes timely terminal cell cycle exit during pupal development. Partial loss of function increases E2F-dependent transcription and causes ectopic S phase and mitosis after neighboring wild-type cells have become postmitotic, consistent with chaperoning of cell-cycle/APC-C regulators.

"In Hsp83(6-55) mutant clones, E2F-dependent transcription increases and cells show ectopic S phase and mitosis after neighboring cells have exited the cell cycle"
Hsp83 is essential and required throughout spermatogenesis, particularly for microtubule-dependent steps; biochemical data indicate an indirect role via stabilization/maturation of microtubule effectors and signaling components rather than direct tubulin polymerization.

"Phenotypically, **all stages of spermatogenesis involving microtubule function are affected**, from early mitotic divisions through sperm maturation and individualization/motility (yue1999geneticanalysisof pages 1-2). In a viable male-sterile allele (*scratch*), Hsp83/Hsp90 protein was reduced by **~3-fold** (ovaries, testes, male bodies), correlating with fully penetrant male sterility (yue1999geneticanalysisof pages 5-7). Biochemically, only a small fraction of Hsp83 co-purifies with taxol-stabilized microtubule proteins, and Hsp83 does not remain bound through repeated microtubule assembly/disassembly, supporting an **indirect role** via stabilization/maturation of microtubule effectors and/or signaling components rather than direct tubulin polymerization"
Hsp83 contributes to female fertility and oogenesis, interacting with the translational regulator Cup and affecting maternal mRNA handling, including nanos mRNA localization relevant to anterior-posterior embryonic patterning.

"Hsp83 also contributes to female fertility, oogenesis, and maternal RNA regulation. It interacts with the translational regulator Cup during oogenesis, localizes maternal transcripts, and affects *nanos* mRNA localization, linking Hsp83 to anterior–posterior patterning in embryos."
Hsp83/Hsp90 buffers cryptic genetic variation and supports fitness in natural fly populations; reduced expression lowers fecundity and longevity and weakens robustness, especially under inbreeding and mild heat stress, supporting the classic capacitor (canalization) model in a population context.

"Hsp83/Hsp90 buffers cryptic genetic variation and supports fitness in natural fly populations. Reduced Hsp83 expression from naturally occurring insertions lowers fecundity and longevity and weakens robustness, especially under inbreeding and mild heat stress, supporting the classic"
Hsp83 can act as a constitutive proteostasis factor whose transcription is not necessarily induced in all proteotoxic stress states; in a 2023 larval fat body study Hsp83 (and Gp93) did not change despite induction of Hsp70/Hsp40-class stress genes, qualifying the strength of an inducible heat-response annotation.

"A 2023 Nature Communications study in Drosophila larval fat body found that **Nacα reduction activates a heat shock response**, with upregulation of Hsp70/Hsp40 class genes and oxidative stress markers, but **Hsp83 (and another Hsp90-family gene Gp93) did not change** in that context (qRT-PCR, n=4 batches)"

Deep Research

Falcon

(Hsp83-deep-research-falcon.md)

this with annotations you find in gene/protein databases, but these can be outdated or inaccurate. Falcon Edison Scientific Literature 33 citations 2 artifacts 2026-05-30T19:45:23.548993

Edison artifact artifact-00 (text/markdown)

## Context ID: pqac-00000015 The ectopic proliferation and cell cycle exit defect in *Hsp83* (6-55) mutant cells is shown in Figures 1 and 2. - **Figure 1**: Pa (image/png)

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Research report: Functional annotation of Hsp83 (UniProt P02828) in Drosophila melanogaster

0) Target verification (mandatory disambiguation)

The target protein is Heat shock protein 83 (Hsp83; also called Hsp82/Hsp90) from **
Drosophila melanogaster, corresponding to the cytosolic Hsp90-family ATP-dependent molecular chaperone. Drosophila genetics papers explicitly refer to Hsp83 as the Hsp90 homolog and study loss-of-function alleles of Hsp83 in D. melanogaster (yue1999geneticanalysisof pages 1-2, bandura2013themolecularchaperone pages 3-4). This aligns with the UniProt description for P02828 (cytosolic Hsp90 family chaperone) and with canonical Hsp90 cycle/co-chaperone dependencies (prodromou2022advancestowardsunderstanding pages 1-3, oostenhawle2023organismalrolesof pages 1-3).

1) Key concepts and definitions (current understanding)

1.1 Core molecular function

Hsp83 is best understood as the cytosolic Hsp90 ATP-dependent chaperone that promotes late-stage folding/maturation, stabilization, and activation of diverse client proteins, especially those central to signaling and development (prodromou2022advancestowardsunderstanding pages 1-3, oostenhawle2023organismalrolesof pages 1-3). Mechanistically, Hsp90 proteins are dimeric, undergoing an ATP-driven conformational cycle involving ATP binding/hydrolysis and large structural rearrangements that enable remodeling/maturation of clients (prodromou2022advancestowardsunderstanding pages 1-3, somogyvari2022hsp90fromcellular pages 5-6).

1.2 Chaperone cycle partners (co-chaperones)

Hsp90/Hsp83 function is regulated by co-chaperones that modulate client recruitment and ATPase cycling. Key named regulators include Cdc37 (kinase client recruitment), p23, and Aha1, as well as TPR-domain proteins such as Hop that bind the conserved MEEVD C-terminal motif typical of cytosolic Hsp90s (prodromou2022advancestowardsunderstanding pages 1-3, somogyvari2022hsp90fromcellular pages 3-5). This co-chaperone control is context-specific and central to how Hsp83 supports distinct pathways at different times and tissues (oostenhawle2023organismalrolesof pages 1-3).

2) Drosophila-specific functional annotation (processes, pathways, localization)

2.1 Subcellular localization

Direct immunofluorescence in Drosophila testes shows predominantly cytoplasmic Hsp83 in spermatocytes, with weak but reproducible nuclear staining in primary spermatocytes, plus strong staining of spermatid bundles and punctate staining along sperm tails (yue1999geneticanalysisof pages 5-7). This pattern is consistent with a primarily cytosolic chaperone that can also be present in/near nuclei in specific developmental contexts.

2.2 Essentiality and organismal roles in development

Hsp83 is essential: strong Hsp83 point mutations are lethal as homozygotes (yue1999geneticanalysisof pages 1-2). In a large Drosophila developmental screen for cell-cycle-exit regulators, an Hsp83 allele (6-55; predicted P380S) showed pupal lethality in animals composed entirely of homozygous mutant cells (bandura2013themolecularchaperone pages 3-4). Broader synthesis across metazoans emphasizes Hsp90’s centrality to organismal proteostasis, signaling, development, and stress adaptation, which provides a framework for interpreting Hsp83 pleiotropy (oostenhawle2023organismalrolesof pages 1-3).

2.3 Spermatogenesis: requirement for microtubule-dependent processes

A canonical Drosophila genetic analysis found eight transheterozygous Hsp83 mutant combinations that yield viable adults, all with sterile males and sterile/weakly fertile females (yue1999geneticanalysisof pages 1-2). Phenotypically, all stages of spermatogenesis involving microtubule function are affected, from early mitotic divisions through sperm maturation and individualization/motility (yue1999geneticanalysisof pages 1-2). In a viable male-sterile allele (scratch), Hsp83/Hsp90 protein was reduced by ~3-fold (ovaries, testes, male bodies), correlating with fully penetrant male sterility (yue1999geneticanalysisof pages 5-7). Biochemically, only a small fraction of Hsp83 co-purifies with taxol-stabilized microtubule proteins, and Hsp83 does not remain bound through repeated microtubule assembly/disassembly, supporting an indirect role via stabilization/maturation of microtubule effectors and/or signaling components rather than direct tubulin polymerization (yue1999geneticanalysisof pages 1-2).

2.4 Oogenesis, maternal contribution, and embryonic patterning

A focused review on maternal heat shock proteins summarizes Drosophila evidence that Hsp83 contributes to female fertility and oogenesis and is involved in maternal mRNA handling, including effects on **
nanos mRNA localization important for anterior–posterior patterning (christians2017heatshockproteins pages 3-6). The same synthesis notes that some Hsp83 mutant combinations can have very low viability (<1%)** and surviving females can be weakly fertile or sterile, indicating strong reproductive sensitivity to reduced Hsp83 function (christians2017heatshockproteins pages 3-6).

2.5 Hormone signaling pathway 1: Ecdysone receptor activation (steroid receptor biology)

A key Drosophila primary study demonstrated that the ecdysone receptor heterodimer EcR/USP requires an Hsp83/Hsp90-containing multichaperone complex for activation. Purified components—Hsp83 (Hsp90), Hsc70, Hop, Hip, FKBP52, and p23—were sufficient to reconstitute functional EcR/USP DNA binding in vitro, and activation required ATP hydrolysis and Mg2+ (arbeitman2000molecularchaperonesactivate pages 3-4, arbeitman2000molecularchaperonesactivate pages 4-5). Pharmacological inhibition by the Hsp90 inhibitor geldanamycin nearly abolished DNA binding, quantified as ~58-fold inhibition by phosphorimager analysis, and inhibition mapped to EcR rather than USP (arbeitman2000molecularchaperonesactivate pages 5-7).

In vivo functional relevance was supported by an ecdysone-inducible reporter assay: pretreatment with 0.1 mg/ml and 1.0 mg/ml geldanamycin reduced reporter activity to 71% and 21% of control (experiments repeated three times), consistent with a role for Hsp83/Hsp90 in receptor maturation (arbeitman2000molecularchaperonesactivate pages 7-8).

2.6 Hormone signaling pathway 2: Juvenile hormone (JH) receptor Met nuclear import

In Drosophila juvenile hormone signaling, Hsp83 physically interacts with the JH receptor Methoprene-tolerant (Met), and JH increases the Met–Hsp83 interaction. Hsp83 loss-of-function attenuates JH binding and reduces JH-induced nuclear import of Met, decreasing JH-responsive transcription of Kr-h1 (he2014heatshockprotein pages 1-2). This provides direct evidence that Hsp83 can regulate signaling by controlling receptor localization and competence.

2.7 Cell cycle exit and developmental proliferation control

Hsp83 promotes timely cell cycle exit during pupal development. In Hsp83(6-55) mutant clones, E2F-dependent transcription increases and cells show ectopic S phase and mitosis after neighboring cells have exited the cell cycle (bandura2013themolecularchaperone pages 3-4, bandura2013themolecularchaperone pages 4-7). Flow cytometry at ~24–28 hr after puparium formation showed that ~10% of mutant-clone cells retained G2 (4N) DNA content, whereas nearly all wild-type cells were in G1 (2N) at that stage (bandura2013themolecularchaperone pages 4-7). This phenotype is also documented visually in Figures 1–2 of the same paper (bandura2013themolecularchaperone media 1b422e67, bandura2013themolecularchaperone media c9b82fe2).

3) Recent developments and latest research (prioritizing 2023–2024)

3.1 2023: organismal and inter-tissue roles of Hsp90

A 2023 review synthesizes emerging evidence that metazoan Hsp90 function extends beyond cell-autonomous proteostasis to inter-tissue stress signaling and organismal coordination of proteostasis, influencing development, aging, immunity, and evolution (oostenhawle2023organismalrolesof pages 1-3). Although not exclusively Drosophila-focused, this review is widely relevant to interpreting Hsp83 phenotypes as outcomes of altered signaling-client maturation and organism-wide proteostasis capacity.

3.2 2023: tissue proteostasis response where Hsp83 is not induced

A 2023 Nature Communications study in Drosophila larval fat body found that Nacα reduction activates a heat shock response, with upregulation of Hsp70/Hsp40 class genes and oxidative stress markers, but Hsp83 (and another Hsp90-family gene Gp93) did not change in that context (qRT-PCR, n=4 batches) (yamada2023nacαprotectsthe pages 11-12). This provides recent evidence that Hsp83 can act as a constitutive proteostasis factor whose transcription is not necessarily an inducible output in all proteotoxic stress states.

3.3 2024: structural proteomics and orthology context (supporting identity)

A 2024 bioRxiv preprint on host–microbe protein mimicry explicitly references Drosophila cytoplasmic Hsp83 (UniProt P02828) in phylogenetic/structural analyses, supporting consistent use of P02828 as Drosophila Hsp83 in recent bioinformatic pipelines (paper retrieved; not cited for functional claims here beyond identity alignment).

4) Current applications and real-world implementations

Endocrine and developmental biology model: Hsp83 is experimentally tractable as a required factor for activation of the steroid receptor EcR/USP and the JH receptor Met, enabling mechanistic dissection of hormone-controlled development and metamorphosis (he2014heatshockprotein pages 1-2, arbeitman2000molecularchaperonesactivate pages 5-7).
Chemical biology / target validation platform: Hsp90 inhibitors (e.g., geldanamycin) can be used in Drosophila cells/assays to perturb receptor maturation and transcriptional outputs, as shown for ecdysone signaling (arbeitman2000molecularchaperonesactivate pages 7-8).
Developmental cell-cycle control: Drosophila Hsp83 mutant mosaic analysis provides an in vivo platform to study how proteostasis capacity couples to cell cycle exit and APC/C-related regulation (bandura2013themolecularchaperone pages 4-7).
Evolution and robustness (canalization) in natural populations: Hsp83 serves as a mechanistic entry point to study buffering of cryptic genetic variation under environmental stress (chen2012hsp90isimportant pages 1-2).

5) Expert opinions and analysis (authoritative synthesis)

A consistent expert synthesis across Hsp90 literature is that Hsp90 proteins are not generic “holdases” but ATP-driven machines that support signal transduction proteomes by stabilizing and enabling conformational maturation of clients (notably kinases and nuclear receptors), with outcomes depending on specific co-chaperone complexes and cellular context (prodromou2022advancestowardsunderstanding pages 1-3, oostenhawle2023organismalrolesof pages 1-3). The Drosophila primary studies fit this model: Hsp83 acts upstream of (i) steroid receptor activation (EcR), (ii) hormone receptor nuclear import (Met), and (iii) developmental control of proliferation/cell cycle exit, each of which plausibly depends on a limited set of Hsp83 clients and co-chaperone states (he2014heatshockprotein pages 1-2, bandura2013themolecularchaperone pages 4-7, arbeitman2000molecularchaperonesactivate pages 5-7).

6) Statistics and data highlights (recent and foundational)

Ecdysone receptor activation: Geldanamycin causes ~58-fold inhibition of EcRE DNA binding in vitro (phosphorimager quantification) and reduces an ecdysone-inducible reporter to 71% (0.1 mg/ml) or 21% (1.0 mg/ml) of control (3 repeats) (arbeitman2000molecularchaperonesactivate pages 5-7, arbeitman2000molecularchaperonesactivate pages 7-8).
Cell cycle exit defect: A genetic screen examined ~185,500 animals and identified 61 mutant lines; Hsp83 mutant clones show ~10% G2 (4N) cells vs near-complete G1 (2N) in wild-type at 24–28 hr APF, with visible ectopic PCNA/BrdU/PH3 signals (bandura2013themolecularchaperone pages 3-4, bandura2013themolecularchaperone pages 4-7, bandura2013themolecularchaperone media 1b422e67).
Spermatogenesis: Eight viable transheterozygous Hsp83 mutant combinations yield adults with sterile males; the scratch allele shows an ~3-fold reduction in Hsp83/Hsp90 protein (yue1999geneticanalysisof pages 1-2, yue1999geneticanalysisof pages 5-7).
Natural populations: Screening >4500 flies from 42 populations identified low-frequency insertion/deletion variants near Hsp83 associated with reduced expression and reduced fitness/robustness, including extinction of inbred mutant populations at slightly elevated temperature (chen2012hsp90isimportant pages 1-2).
2023 tissue stress response: In larval fat body, qRT-PCR (n=4 batches) shows Hsp83 expression unchanged under Nacα knockdown despite induction of other stress genes (yamada2023nacαprotectsthe pages 11-12).

Evidence summary table

Aspect	Key findings	Quantitative/statistical details	Key source (author year) with URL	Citation ID
Molecular function / co-chaperones	Hsp83 is the sole cytosolic Hsp90-family chaperone in D. melanogaster and functions as an ATP-dependent molecular chaperone that promotes late-stage folding, maturation, stabilization, and activation of signaling clients. Its cycle is regulated by co-chaperones including Cdc37, p23, Aha1, and TPR-domain proteins such as Hop that bind the conserved MEEVD tail.	General Hsp90 reviews report Hsp90 at ~1–2% of total cellular protein and >300 confirmed clients across systems; these values are not Drosophila-specific but are widely used to contextualize Hsp83 function.	van Oosten-Hawle 2023 https://doi.org/10.3390/biom13020251; Prodromou & Bjorklund 2022 https://doi.org/10.3390/biom12050600	(prodromou2022advancestowardsunderstanding pages 1-3, oostenhawle2023organismalrolesof pages 1-3)
Localization	Drosophila Hsp83 is primarily cytosolic, consistent with its designation as the sole cytosolic Hsp90. In testes, immunostaining showed strong cytoplasmic signal in spermatocytes, weak but reproducible nuclear staining in primary spermatocytes, cortical mesh-like staining, strong staining in spermatid bundles, and punctate signal along sperm tails.	In one viable allele (scratch), Hsp90 protein levels were reduced about threefold in ovaries, testes, and male bodies, providing a quantitative context for the observed localization/phenotype analyses.	Yue et al. 1999 https://doi.org/10.1093/genetics/151.3.1065; Castorena et al. 2007 https://doi.org/10.1128/jvi.00189-07	(yue1999geneticanalysisof pages 5-7)
Developmental roles	Hsp83 is essential for viability and normal development. Homozygous point mutants are lethal, while certain transheterozygous combinations produce viable adults with strong reproductive defects, showing that partial Hsp83 function can support development but not normal gametogenesis.	Eight transheterozygous mutant combinations yielded viable adults; some stronger combinations had very low viability (<1%) in later summaries of the underlying mutant series.	Yue et al. 1999 https://doi.org/10.1093/genetics/151.3.1065; Christians 2017 https://doi.org/10.1007/978-3-319-51409-3_1	(yue1999geneticanalysisof pages 1-2, christians2017heatshockproteins pages 3-6)
Spermatogenesis	Hsp83 is required throughout spermatogenesis, especially for processes dependent on microtubule function. Mutant males are sterile, with defects spanning early mitoses, sperm maturation, individualization, and motility; evidence supports an indirect role through maintenance of signaling/microtubule effectors rather than direct structural assembly of microtubules.	All eight viable transheterozygous combinations had sterile males; in the scratch allele, male sterility was fully penetrant and correlated with an ~3-fold reduction in Hsp90 protein.	Yue et al. 1999 https://doi.org/10.1093/genetics/151.3.1065	(yue1999geneticanalysisof pages 1-2, yue1999geneticanalysisof pages 5-7)
Oogenesis / maternal function	Hsp83 also contributes to female fertility, oogenesis, and maternal RNA regulation. It interacts with the translational regulator Cup during oogenesis, localizes maternal transcripts, and affects nanos mRNA localization, linking Hsp83 to anterior–posterior patterning in embryos.	Surviving females from some mutant combinations were weakly fertile or sterile; one summarized mutant combination (R48C + S592F) caused oogenesis arrest beyond stage 9.	Christians 2017 https://doi.org/10.1007/978-3-319-51409-3_1	(christians2017heatshockproteins pages 3-6)
Cell cycle exit	Hsp83 is required for timely terminal cell cycle exit in pupal tissues. Partial loss of function increases E2F-dependent transcription, causes ectopic S phase and mitosis after wild-type cells have become postmitotic, and appears to impair APC/C-Cdh1/Fzr-dependent shutdown of proliferation.	A screen of ~185,500 animals identified 61 mutant lines; in pupal wings ~1% of mutant cells were PH3-positive at 28 h APF, and flow cytometry showed ~10% of mutant-clone cells retained G2 (4N) DNA content whereas almost all wild-type cells were in G1 (2N).	Bandura et al. 2013 https://doi.org/10.1371/journal.pgen.1003835	(bandura2013themolecularchaperone pages 3-4, bandura2013themolecularchaperone pages 4-7, bandura2013themolecularchaperone media 1b422e67)
Hormone signaling (juvenile hormone)	Hsp83 facilitates juvenile hormone signaling by promoting nuclear import of the JH receptor Methoprene-tolerant (Met). Hsp83 physically interacts with Met, JH enhances this interaction, and Hsp83 loss of function reduces JH binding and JH-responsive transcription of Kr-h1.	A 120-bp juvenile hormone response region (JHRR) in the Kr-h1 promoter was identified; the excerpt does not provide numeric effect sizes for Hsp83-dependent changes in reporter activity or nuclear import.	He et al. 2014 https://doi.org/10.1074/jbc.m114.582825	(he2014heatshockprotein pages 1-2)
Stress response expression	In a 2023 Drosophila larval fat body proteostasis study, Hsp83 expression did not increase during Nacα knockdown despite strong induction of Hsp70/Hsp40-class stress genes and oxidative-stress markers. This suggests that Hsp83 is not a universally induced output of all proteotoxic stress states and may remain constitutive in some tissues/conditions.	qRT-PCR was performed on mid-third-instar larval fat body with n = 4 batches; Hsp83 and Gp93 were unchanged, whereas Hsp70Ba, DnaJ-1, and Stip1 were upregulated qualitatively.	Yamada et al. 2023 https://doi.org/10.1038/s41467-023-41103-1	(yamada2023nacαprotectsthe pages 11-12)
Evolutionary buffering	Hsp83/Hsp90 buffers cryptic genetic variation and supports fitness in natural fly populations. Reduced Hsp83 expression from naturally occurring insertions lowers fecundity and longevity and weakens robustness, especially under inbreeding and mild heat stress, supporting the classic “capacitor” model in a population context.	>4500 flies from 42 wild populations were screened; Hsp83 insertions were low-frequency, reduced expression, and inbred mutant populations went extinct at slightly elevated temperature whereas inbred wild-type populations persisted.	Chen & Wagner 2012 https://doi.org/10.1186/1471-2148-12-25; van Oosten-Hawle 2023 https://doi.org/10.3390/biom13020251	(chen2012hsp90isimportant pages 1-2, oostenhawle2023organismalrolesof pages 1-3)

Table: This table summarizes experimentally supported functional annotation evidence for Drosophila melanogaster Hsp83 (UniProt P02828). It highlights molecular function, localization, developmental and signaling roles, and quantitative findings useful for gene/protein annotation.

Visual evidence (selected)

Bandura et al. 2013 Figures 1–2 provide direct in vivo evidence (reporters, BrdU/PH3 staining, and flow cytometry) that partial loss of Hsp83 impairs developmental cell cycle exit and leaves a measurable fraction of cells in G2 in pupal tissues (bandura2013themolecularchaperone media 1b422e67, bandura2013themolecularchaperone media c9b82fe2).

Practical functional annotation statement (concise)

Hsp83 (P02828) encodes the essential cytosolic Hsp90 ATP-dependent chaperone in
D. melanogaster, operating via an ATPase-driven cycle regulated by co-chaperones (e.g., Hop, p23, Aha1, Cdc37) to mature key signaling clients. Experimentally, Hsp83 is required for activation of the EcR/USP ecdysone receptor, supports juvenile hormone signaling by enabling Met nuclear import, is essential for proper spermatogenesis (microtubule-dependent steps), contributes to maternal/oogenic functions, and promotes timely developmental cell cycle exit. (he2014heatshockprotein pages 1-2, bandura2013themolecularchaperone pages 4-7, yue1999geneticanalysisof pages 5-7, arbeitman2000molecularchaperonesactivate pages 5-7)

References

(yue1999geneticanalysisof pages 1-2): Lin Yue, Timothy L Karr, Debra F Nathan, Hewson Swift, Shaila Srinivasan, and Susan Lindquist. Genetic analysis of viable hsp90 alleles reveals a critical role in drosophila spermatogenesis. Genetics, 151:1065-1079, Mar 1999. URL: https://doi.org/10.1093/genetics/151.3.1065, doi:10.1093/genetics/151.3.1065. This article has 171 citations and is from a domain leading peer-reviewed journal.
(bandura2013themolecularchaperone pages 3-4): Jennifer L. Bandura, Huaqi Jiang, Derek W. Nickerson, and Bruce A. Edgar. The molecular chaperone hsp90 is required for cell cycle exit in drosophila melanogaster. PLoS Genetics, 9:e1003835, Sep 2013. URL: https://doi.org/10.1371/journal.pgen.1003835, doi:10.1371/journal.pgen.1003835. This article has 30 citations and is from a domain leading peer-reviewed journal.
(prodromou2022advancestowardsunderstanding pages 1-3): Chrisostomos Prodromou and Dennis M. Bjorklund. Advances towards understanding the mechanism of action of the hsp90 complex. Biomolecules, 12:600, Apr 2022. URL: https://doi.org/10.3390/biom12050600, doi:10.3390/biom12050600. This article has 52 citations.
(oostenhawle2023organismalrolesof pages 1-3): Patricija van Oosten-Hawle. Organismal roles of hsp90. Biomolecules, 13:251, Jan 2023. URL: https://doi.org/10.3390/biom13020251, doi:10.3390/biom13020251. This article has 32 citations.
(somogyvari2022hsp90fromcellular pages 5-6): Milán Somogyvári, Saba Khatatneh, and Csaba Sőti. Hsp90: from cellular to organismal proteostasis. Cells, 11:2479, Aug 2022. URL: https://doi.org/10.3390/cells11162479, doi:10.3390/cells11162479. This article has 44 citations.
(somogyvari2022hsp90fromcellular pages 3-5): Milán Somogyvári, Saba Khatatneh, and Csaba Sőti. Hsp90: from cellular to organismal proteostasis. Cells, 11:2479, Aug 2022. URL: https://doi.org/10.3390/cells11162479, doi:10.3390/cells11162479. This article has 44 citations.
(yue1999geneticanalysisof pages 5-7): Lin Yue, Timothy L Karr, Debra F Nathan, Hewson Swift, Shaila Srinivasan, and Susan Lindquist. Genetic analysis of viable hsp90 alleles reveals a critical role in drosophila spermatogenesis. Genetics, 151:1065-1079, Mar 1999. URL: https://doi.org/10.1093/genetics/151.3.1065, doi:10.1093/genetics/151.3.1065. This article has 171 citations and is from a domain leading peer-reviewed journal.
(christians2017heatshockproteins pages 3-6): Elisabeth S. Christians. Heat shock proteins and maternal contribution to oogenesis and early embryogenesis. Advances in anatomy, embryology, and cell biology, 222:1-27, Jan 2017. URL: https://doi.org/10.1007/978-3-319-51409-3_1, doi:10.1007/978-3-319-51409-3_1. This article has 9 citations.
(arbeitman2000molecularchaperonesactivate pages 3-4): Michelle N Arbeitman and David S Hogness. Molecular chaperones activate the drosophila ecdysone receptor, an rxr heterodimer. Cell, 101:67-77, Mar 2000. URL: https://doi.org/10.1016/s0092-8674(00)80624-8, doi:10.1016/s0092-8674(00)80624-8. This article has 201 citations and is from a highest quality peer-reviewed journal.
(arbeitman2000molecularchaperonesactivate pages 4-5): Michelle N Arbeitman and David S Hogness. Molecular chaperones activate the drosophila ecdysone receptor, an rxr heterodimer. Cell, 101:67-77, Mar 2000. URL: https://doi.org/10.1016/s0092-8674(00)80624-8, doi:10.1016/s0092-8674(00)80624-8. This article has 201 citations and is from a highest quality peer-reviewed journal.
(arbeitman2000molecularchaperonesactivate pages 5-7): Michelle N Arbeitman and David S Hogness. Molecular chaperones activate the drosophila ecdysone receptor, an rxr heterodimer. Cell, 101:67-77, Mar 2000. URL: https://doi.org/10.1016/s0092-8674(00)80624-8, doi:10.1016/s0092-8674(00)80624-8. This article has 201 citations and is from a highest quality peer-reviewed journal.
(arbeitman2000molecularchaperonesactivate pages 7-8): Michelle N Arbeitman and David S Hogness. Molecular chaperones activate the drosophila ecdysone receptor, an rxr heterodimer. Cell, 101:67-77, Mar 2000. URL: https://doi.org/10.1016/s0092-8674(00)80624-8, doi:10.1016/s0092-8674(00)80624-8. This article has 201 citations and is from a highest quality peer-reviewed journal.
(he2014heatshockprotein pages 1-2): Qianyu He, Di Wen, Qiangqiang Jia, Chunlai Cui, Jian Wang, Subba R. Palli, and Sheng Li. Heat shock protein 83 (hsp83) facilitates methoprene-tolerant (met) nuclear import to modulate juvenile hormone signaling. Journal of Biological Chemistry, 289:27874-27885, Oct 2014. URL: https://doi.org/10.1074/jbc.m114.582825, doi:10.1074/jbc.m114.582825. This article has 106 citations and is from a domain leading peer-reviewed journal.
(bandura2013themolecularchaperone pages 4-7): Jennifer L. Bandura, Huaqi Jiang, Derek W. Nickerson, and Bruce A. Edgar. The molecular chaperone hsp90 is required for cell cycle exit in drosophila melanogaster. PLoS Genetics, 9:e1003835, Sep 2013. URL: https://doi.org/10.1371/journal.pgen.1003835, doi:10.1371/journal.pgen.1003835. This article has 30 citations and is from a domain leading peer-reviewed journal.
(bandura2013themolecularchaperone media 1b422e67): Jennifer L. Bandura, Huaqi Jiang, Derek W. Nickerson, and Bruce A. Edgar. The molecular chaperone hsp90 is required for cell cycle exit in drosophila melanogaster. PLoS Genetics, 9:e1003835, Sep 2013. URL: https://doi.org/10.1371/journal.pgen.1003835, doi:10.1371/journal.pgen.1003835. This article has 30 citations and is from a domain leading peer-reviewed journal.
(bandura2013themolecularchaperone media c9b82fe2): Jennifer L. Bandura, Huaqi Jiang, Derek W. Nickerson, and Bruce A. Edgar. The molecular chaperone hsp90 is required for cell cycle exit in drosophila melanogaster. PLoS Genetics, 9:e1003835, Sep 2013. URL: https://doi.org/10.1371/journal.pgen.1003835, doi:10.1371/journal.pgen.1003835. This article has 30 citations and is from a domain leading peer-reviewed journal.
(yamada2023nacαprotectsthe pages 11-12): Takayuki Yamada, Yuto Yoshinari, Masayuki Tobo, Okiko Habara, and Takashi Nishimura. Nacα protects the larval fat body from cell death by maintaining cellular proteostasis in drosophila. Nature Communications, Sep 2023. URL: https://doi.org/10.1038/s41467-023-41103-1, doi:10.1038/s41467-023-41103-1. This article has 10 citations and is from a highest quality peer-reviewed journal.
(chen2012hsp90isimportant pages 1-2): Bing Chen and Andreas Wagner. Hsp90 is important for fecundity, longevity, and buffering of cryptic deleterious variation in wild fly populations. BMC Evolutionary Biology, 12:25-25, Feb 2012. URL: https://doi.org/10.1186/1471-2148-12-25, doi:10.1186/1471-2148-12-25. This article has 102 citations and is from a domain leading peer-reviewed journal.

Artifacts

Edison artifact artifact-00

Citations

oostenhawle2023organismalrolesof pages 1-3
yue1999geneticanalysisof pages 5-7
yue1999geneticanalysisof pages 1-2
bandura2013themolecularchaperone pages 3-4
christians2017heatshockproteins pages 3-6
arbeitman2000molecularchaperonesactivate pages 5-7
arbeitman2000molecularchaperonesactivate pages 7-8
he2014heatshockprotein pages 1-2
bandura2013themolecularchaperone pages 4-7
prodromou2022advancestowardsunderstanding pages 1-3
arbeitman2000molecularchaperonesactivate pages 3-4
arbeitman2000molecularchaperonesactivate pages 4-5
https://doi.org/10.3390/biom13020251;
https://doi.org/10.3390/biom12050600
https://doi.org/10.1093/genetics/151.3.1065;
https://doi.org/10.1128/jvi.00189-07
https://doi.org/10.1007/978-3-319-51409-3_1
https://doi.org/10.1093/genetics/151.3.1065
https://doi.org/10.1371/journal.pgen.1003835
https://doi.org/10.1074/jbc.m114.582825
https://doi.org/10.1038/s41467-023-41103-1
https://doi.org/10.1186/1471-2148-12-25;
https://doi.org/10.3390/biom13020251
https://doi.org/10.1093/genetics/151.3.1065,
https://doi.org/10.1371/journal.pgen.1003835,
https://doi.org/10.3390/biom12050600,
https://doi.org/10.3390/biom13020251,
https://doi.org/10.3390/cells11162479,
https://doi.org/10.1007/978-3-319-51409-3_1,
https://doi.org/10.1016/s0092-8674(00
https://doi.org/10.1074/jbc.m114.582825,
https://doi.org/10.1038/s41467-023-41103-1,
https://doi.org/10.1186/1471-2148-12-25,

📚 Additional Documentation

Bioreason Rl Predictions

(Hsp83-bioreason-rl-predictions.md)

BioReason Chat Export

Exported on March 22, 2026 at 02:50 AM

Organism: Drosophila melanogaster

Sequence:

MPEEAETFAFQAEIAQLMSLIINTFYSNKEIFLRELISNASDALDKIRYESLTDPSKLDSGKELYIKLIPNKTAGTLTIIDTGIGMTKSDLVNNLGTIAKSGTKAFMEALQAGADISMIGQFGVGFYSAYLVADKVTVTSKNNDDEQYVWESSAGGSFTVRADNSEPLGRGTKIVLYIKEDQTDYLEESKIKEIVNKHSQFIGYPIKLLVEKEREKEVSDDEADDEKKEGDEKKEMETDEPKIEDVGEDEDADKKDKDAKKKKTIKEKYTEDEELNKTKPIWTRNPDDISQEEYGEFYKSLTNDWEDHLAVKHFSVEGQLEFRALLFIPRRTPFDLFENQKKRNNIKLYVRRVFIMDNCEDLIPEYLNFMKGVVDSEDLPLNISREMLQQNKVLKVIRKNLVKKTMELIEELTEDKENYKKFYDQFSKNLKLGVHEDSNNRAKLADFLRFHTSASGDDFCSLADYVSRMKDNQKHVYFITGESKDQVSNSAFVERVKARGFEVVYMTEPIDEYVIQHLKEYKGKQLVSVTKEGLELPEDESEKKKREEDKAKFESLCKLMKSILDNKVEKVVVSNRLVDSPCCIVTSQFGWSANMERIMKAQALRDTATMGYMAGKKQLEINPDHPIVETLRQKADADKNDKAVKDLVILLFETSLLSSGFSLDSPQVHASRIYRMIKLGLGIDEDEPMTTDDAQSAGDAPSLVEDTEDASHMEEVD

Thinking Trace

The architecture begins with IPR036890 (Histidine kinase/HSP90-like ATPase superfamily, residues 1–226), which frames the N-terminal ATPase engine characteristic of nucleotide-dependent chaperones. Nested within this region is IPR001404 (Heat shock protein Hsp90 family, residues 3–714), marking the entire polypeptide as an Hsp90-class chaperone. The core N-terminal module is refined by IPR020575 (Heat shock protein Hsp90, N-terminal domain, residues 6–206) and the catalytic scaffold IPR003594 (Histidine kinase/HSP90-like ATPase domain, residues 28–182), together with the diagnostic IPR019805 (Heat shock protein Hsp90, conserved site, residues 26–35). This arrangement creates an ATP-binding pocket and hydrolysis cycle that drives client capture and release. Midway through the sequence, residues 277–532 match IPR020568 (Ribosomal protein uS5 domain 2-type superfamily), a structural homology that contributes a rigid middle domain often used by Hsp90s for client and co-chaperone engagement. The C-terminal region is capped by IPR037196 (HSP90, C-terminal domain, residues 532–681), which forms the dimerization interface and coordinates ATPase timing across subunits. The ordered progression—N-terminal ATPase core, client-interacting middle body, and C-terminal dimerization platform—causes ATP-coupled chaperone activity.

From this domain logic, the molecular function resolves as ATP-dependent chaperoning. The N-terminal HSP90-like ATPase domains (IPR036890, IPR020575, IPR003594) necessitate nucleotide handling and hydrolysis, supporting ATP binding and hydrolysis. Thus, the functional slate begins with GO:0005524 ATP binding and extends to GO:0016887 ATPase activity. The conserved Hsp90 site and full-family signature (IPR001404) specify a heat-shock chaperone that binds non-native polypeptides and remodels them via conformational cycling.

These ATP-driven conformational changes feed directly into biological processes of proteostasis. By stabilizing non-native states and guiding folding trajectories, the protein executes GO:0006457 protein folding and contributes to stress recovery pathways typified by GO:0009408 response to heat. The middle-domain homology to a uS5-like fold suggests robust client engagement, consistent with roles in assembling and maintaining multi-protein complexes during stress and recovery.

Cellular context follows from the soluble, dimeric architecture and absence of transmembrane segments or secretion signals. Hsp90-family chaperones predominantly operate in the cytosol, where nascent chains and stress-labile factors accumulate. This supports a soluble localization consistent with the cytoplasm, formalized as GO:0005737 cytoplasm and aligning with the experimentally grounded cytoplasmic assignment.

Mechanistically, the N-terminal ATPase cycle gates a clamp that alternates between open and closed states to capture and release client proteins. The middle domain tunes affinity and specificity, while the C-terminal dimerization hub synchronizes subunits for productive cycling. Likely interaction partners include co-chaperones that dock to the middle and C-terminal regions to choreograph client fate—adaptors that load substrates, nucleotide-state readers that time hydrolysis, and scaffolds that route clients toward assembly or degradation pathways. In Drosophila, this cytosolic machine would transiently associate with client-rich assemblies, coordinating folding and stabilization during thermal and proteotoxic stress.

Functional Summary

A cytosolic ATP-dependent chaperone that uses an N-terminal nucleotide-binding engine, a client-engaging middle body, and a C-terminal dimerization platform to stabilize and remodel non-native polypeptides. By coupling ATP binding and hydrolysis to conformational cycling, it promotes folding and stabilization of stress-labile substrates in the cytoplasm, coordinating proteostasis during heat and proteotoxic challenges through regulated capture-and-release mechanisms.

UniProt Summary

Molecular chaperone.

InterPro Domains

Histidine kinase/HSP90-like ATPase superfamily (IPR036890, homologous_superfamily) — residues 1-226
Heat shock protein Hsp90 family (IPR001404, family) — residues 3-714
Heat shock protein Hsp90, N-terminal (IPR020575, domain) — residues 6-206
Heat shock protein Hsp90, conserved site (IPR019805, conserved_site) — residues 26-35
Histidine kinase/HSP90-like ATPase domain (IPR003594, domain) — residues 28-182
Ribosomal protein uS5 domain 2-type superfamily (IPR020568, homologous_superfamily) — residues 277-532
HSP90, C-terminal domain (IPR037196, homologous_superfamily) — residues 532-681

GO Terms

Molecular Function: molecular_function (GO:0003674), binding (GO:0005488), protein-containing complex binding (GO:0044877), protein binding (GO:0005515), protein domain specific binding (GO:0019904), signaling receptor binding (GO:0005102), insulin receptor binding (GO:0005158), unfolded protein binding (GO:0051082)

Biological Process: biological_process (GO:0008150), localization (GO:0051179), positive regulation of biological process (GO:0048518), regulation of biological process (GO:0050789), reproductive process (GO:0022414), reproduction (GO:0000003), multicellular organismal process (GO:0032501), biological regulation (GO:0065007), response to stimulus (GO:0050896), developmental process (GO:0032502), cellular process (GO:0009987), negative regulation of biological process (GO:0048519), sexual reproduction (GO:0019953), cellular developmental process (GO:0048869), response to abiotic stimulus (GO:0009628), cellular localization (GO:0051641), anatomical structure development (GO:0048856), positive regulation of signaling (GO:0023056), multicellular organism development (GO:0007275), regulation of circadian rhythm (GO:0042752), positive regulation of response to stimulus (GO:0048584), regulation of metabolic process (GO:0019222), cell cycle process (GO:0022402), positive regulation of multicellular organismal process (GO:0051240), pattern specification process (GO:0007389), cell cycle (GO:0007049), cellular component organization or biogenesis (GO:0071840), regulation of multicellular organismal process (GO:0051239), multicellular organism reproduction (GO:0032504), developmental process involved in reproduction (GO:0003006), macromolecule localization (GO:0033036), negative regulation of metabolic process (GO:0009892), regulation of developmental process (GO:0050793), cellular process involved in reproduction in multicellular organism (GO:0022412), protein folding (GO:0006457), regulation of cellular process (GO:0050794), regulation of response to stimulus (GO:0048583), pole plasm RNA localization (GO:0007316), regulation of signaling (GO:0023051), developmental maturation (GO:0021700), response to stress (GO:0006950), microtubule-based process (GO:0007017), positive regulation of developmental process (GO:0051094), negative regulation of cellular process (GO:0048523), multicellular organismal reproductive process (GO:0048609), positive regulation of cellular process (GO:0048522), response to temperature stimulus (GO:0009266), gamete generation (GO:0007276), positive regulation of signal transduction (GO:0009967), germ cell development (GO:0007281), positive regulation of cell differentiation (GO:0045597), oocyte axis specification (GO:0007309), axis specification (GO:0009798), cellular component biogenesis (GO:0044085), cell development (GO:0048468), positive regulation of cellular response to insulin stimulus (GO:1900078), cell differentiation (GO:0030154), negative regulation of cell population proliferation (GO:0008285), regulation of signal transduction (GO:0009966), intracellular mRNA localization involved in pattern specification process (GO:0060810), pole plasm assembly (GO:0007315), oocyte construction (GO:0007308), regulation of macromolecule metabolic process (GO:0060255), microtubule cytoskeleton organization (GO:0000226), pole plasm mRNA localization (GO:0019094), regulation of circadian sleep/wake cycle (GO:0042749), embryonic pattern specification (GO:0009880), response to cold (GO:0009409), anatomical structure maturation (GO:0071695), response to heat (GO:0009408), regulation of cellular response to insulin stimulus (GO:1900076), regulation of multicellular organismal development (GO:2000026), regulation of cell population proliferation (GO:0042127), regionalization (GO:0003002), RNA localization (GO:0006403), regulation of cell communication (GO:0010646), cell maturation (GO:0048469), negative regulation of macromolecule metabolic process (GO:0010605), cellular macromolecule localization (GO:0070727), regulation of cell differentiation (GO:0045595), cellular component organization (GO:0016043), embryo development (GO:0009790), positive regulation of cell communication (GO:0010647), oocyte differentiation (GO:0009994), microtubule organizing center organization (GO:0031023), regulation of behavior (GO:0050795), positive regulation of nervous system development (GO:0051962), centrosome cycle (GO:0007098), positive regulation of cell population proliferation (GO:0008284), segmentation (GO:0035282), oocyte anterior/posterior axis specification (GO:0007314), regulation of insulin receptor signaling pathway (GO:0046626), intracellular mRNA localization (GO:0008298), ribonucleoprotein complex biogenesis (GO:0022613), regulation of cell development (GO:0060284), positive regulation of cell development (GO:0010720), oogenesis (GO:0048477), positive regulation of neural precursor cell proliferation (GO:2000179), positive regulation of insulin receptor signaling pathway (GO:0046628), cytoplasm organization (GO:0007028), intracellular mRNA localization involved in anterior/posterior axis specification (GO:0060811), positive regulation of neurogenesis (GO:0050769), blastoderm segmentation (GO:0007350), regulation of nervous system development (GO:0051960), regulation of gene expression (GO:0010468), anterior/posterior axis specification (GO:0009948), regulation of neural precursor cell proliferation (GO:2000177), cellular component assembly (GO:0022607), regulation of circadian sleep/wake cycle, sleep (GO:0045187), female gamete generation (GO:0007292), oocyte development (GO:0048599), embryonic axis specification (GO:0000578), protein-containing complex organization (GO:0043933), organelle organization (GO:0006996), tripartite regional subdivision (GO:0007351), cold acclimation (GO:0009631), negative regulation of gene expression (GO:0010629), anterior/posterior pattern specification (GO:0009952), protein-containing complex assembly (GO:0065003), RNA-mediated gene silencing (GO:0031047), cytoskeleton organization (GO:0007010), anterior/posterior axis specification, embryo (GO:0008595), ribonucleoprotein complex assembly (GO:0022618), regulation of neuroblast proliferation (GO:1902692), regulation of neurogenesis (GO:0050767), ribonucleoprotein complex subunit organization (GO:0071826), positive regulation of neuroblast proliferation (GO:0002052), proteasome assembly (GO:0043248), maternal determination of anterior/posterior axis, embryo (GO:0008358), RISC complex assembly (GO:0070922)

Cellular Component: cellular_component (GO:0005575), protein-containing complex (GO:0032991), cellular anatomical entity (GO:0110165), microtubule organizing center (GO:0005815), intracellular anatomical structure (GO:0005622), organelle (GO:0043226), endoplasmic reticulum protein-containing complex (GO:0140534), chromosomal region (GO:0098687), membrane (GO:0016020), perinuclear region of cytoplasm (GO:0048471), cytoplasm (GO:0005737), cell periphery (GO:0071944), endomembrane system (GO:0012505), intracellular protein-containing complex (GO:0140535), chaperone complex (GO:0101031), endoplasmic reticulum (GO:0005783), centrosome (GO:0005813), intracellular organelle (GO:0043229), membrane-bounded organelle (GO:0043227), plasma membrane (GO:0005886), polytene chromosome interband (GO:0005705), non-membrane-bounded organelle (GO:0043228), intracellular membrane-bounded organelle (GO:0043231), intracellular non-membrane-bounded organelle (GO:0043232), cytoskeleton (GO:0005856), chromosome (GO:0005694), polytene chromosome (GO:0005700), microtubule cytoskeleton (GO:0015630)

Generated by BioReason

Bioreason Rl Review

(Hsp83-bioreason-rl-review.md)

BioReason-Pro RL Review: Hsp83 (DROME)

Source: Hsp83-bioreason-rl-predictions.md

Correctness: 4/5
Completeness: 3/5

Functional Summary Review

The BioReason summary states:

A cytosolic ATP-dependent chaperone that uses an N-terminal nucleotide-binding engine, a client-engaging middle body, and a C-terminal dimerization platform to stabilize and remodel non-native polypeptides. By coupling ATP binding and hydrolysis to conformational cycling, it promotes folding and stabilization of stress-labile substrates in the cytoplasm, coordinating proteostasis during heat and proteotoxic challenges through regulated capture-and-release mechanisms.

This is a well-articulated description of HSP90 family chaperone function. The curated review confirms Hsp83 as "the sole Drosophila melanogaster member of the HSP90 family of ATP-dependent molecular chaperones" with core molecular function of ATP-dependent protein folding chaperone (GO:0140662).

Strengths:
- Correctly identifies the three-domain architecture (N-terminal ATPase, middle domain, C-terminal dimerization)
- Accurately describes ATP-dependent conformational cycling
- Properly identifies cytosolic localization

Issues:

"Non-native polypeptides" is misleading: The summary describes HSP90 as stabilizing "non-native polypeptides." The curated review explicitly notes that HSP90 "does not function as a holdase chaperone that binds unfolded proteins; it is an ATP-dependent foldase that acts on near-native client proteins." The GO:0051082 (unfolded protein binding) annotation was flagged as inappropriate in the curated review. BioReason repeats this common misconception.
Missing specific client contexts: The curated review documents extensive specific biology: piRNA biogenesis/RISC assembly (GO:0070922), centrosome cycle regulation, pole plasm/mRNA localization, oogenesis, sleep regulation, and insulin receptor signaling. The summary mentions only generic "proteostasis."
Missing non-chaperone membrane-deforming function: The curated review describes Hsp83's non-chaperone "membrane-deforming function mediated by an amphipathic helix that promotes exosome release." This moonlighting activity is absent.
Co-chaperone network not mentioned: Hsp83 interacts with specific co-chaperones (Hop, Shu, Dpit47, Morgana) that modulate its function. The summary mentions "co-chaperones" generically in the thinking trace but not in the functional summary.

Comparison with interpro2go:

The ai-review.yaml contains four GO_REF:0000002 annotations: protein folding (GO:0006457), ATP hydrolysis activity (GO:0016887), unfolded protein binding (GO:0051082), and ATP-dependent protein folding chaperone (GO:0140662). BioReason's summary recapitulates the interpro2go mapping faithfully -- the domain-to-function reasoning produces essentially the same annotations as interpro2go. Notably, BioReason also reproduces the interpro2go error of implying binding to "non-native polypeptides" (analogous to GO:0051082), which the curated review flags as incorrect for HSP90. The curated review accepts GO:0140662 as the correct MF term while noting GO:0051082 is proposed for obsoletion.

Notes on thinking trace

The trace correctly identifies the HSP90-like ATPase domain, the middle domain homology (uS5-like), and the C-terminal dimerization platform. The identification of a "capture-and-release" mechanism driven by ATP hydrolysis is accurate for HSP90 biology.

📄 View Raw YAML

id: P02828
gene_symbol: Hsp83
product_type: PROTEIN
status: DRAFT
taxon:
  id: NCBITaxon:7227
  label: Drosophila melanogaster
description: Hsp83 is the sole Drosophila melanogaster member of the HSP90 family
  of ATP-dependent molecular chaperones. It promotes the maturation, structural maintenance,
  and proper regulation of specific client proteins involved in cell cycle control,
  signal transduction, piRNA biogenesis, and centrosome function. Hsp83 undergoes
  a functional ATPase cycle that induces conformational changes in client proteins,
  thereby causing their activation. It interacts dynamically with various co-chaperones
  (Hop, Shu, Dpit47, Morgana) that modulate its substrate recognition, ATPase cycle,
  and chaperone function. In addition to its canonical chaperone role, Hsp83 has a
  non-chaperone membrane-deforming function mediated by an amphipathic helix that
  promotes exosome release. Hsp83 is constitutively expressed and further induced
  by heat stress; it is also expressed during oogenesis and plays roles in developmental
  processes including centrosome cycle, cell cycle exit, mRNA localization, and sleep
  regulation.
existing_annotations:
- term:
    id: GO:0006457
    label: protein folding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: Hsp83/HSP90 is a well-established molecular chaperone whose primary biological
      role is protein folding. The IBA annotation is supported by strong phylogenetic
      evidence across multiple orthologs (PMID:10716925, UniProt function annotation).
      UniProt states Hsp83 is a "Molecular chaperone that promotes the maturation,
      structural maintenance and proper regulation of specific target proteins."
    action: ACCEPT
    reason: Protein folding is the core biological process of HSP90 family chaperones.
      IBA is well-supported by orthologs and consistent with all functional literature
      on Hsp83.
    supported_by:
    - reference_id: PMID:10716925
      supporting_text: a member of the highly conserved Hsp90 family including chaperones
        known to maintain the activity of many proteins
    - reference_id: file:DROME/Hsp83/Hsp83-deep-research-falcon.md
      supporting_text: |-
        Hsp83 is best understood as the **cytosolic Hsp90 ATP-dependent chaperone** that promotes **late-stage folding/maturation, stabilization, and activation** of diverse client proteins, especially those central to signaling and development
- term:
    id: GO:0016887
    label: ATP hydrolysis activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: Hsp83/HSP90 has intrinsic ATPase activity that is essential for its chaperone
      cycle. The UniProt record notes it "Undergoes a functional cycle that is linked
      to its ATPase activity." The IBA annotation is supported by phylogenetic inference
      from multiple HSP90 orthologs with experimentally characterized ATPase activity.
    action: ACCEPT
    reason: ATP hydrolysis is a core enzymatic activity of the HSP90 family. The HATPase_c
      domain is well characterized structurally and the ATPase cycle drives the chaperone
      conformational changes. Consistent with IBA evidence across the HSP90 family.
    supported_by:
    - reference_id: PMID:29775584
      supporting_text: the Hsp90 system (Hop, Hsp90, and p23) together render Ago2
        into an open, active form
    - reference_id: file:DROME/Hsp83/Hsp83-deep-research-falcon.md
      supporting_text: |-
        Mechanistically, Hsp90 proteins are **dimeric**, undergoing an **ATP-driven conformational cycle** involving **ATP binding/hydrolysis** and large structural rearrangements that enable remodeling/maturation of clients
- term:
    id: GO:0032991
    label: protein-containing complex
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: HSP90 family members function as homodimers and form multi-protein complexes
      with co-chaperones (Hop, p23, Cdc37, Aha1) and client proteins. UniProt states
      Hsp83 is a "Homodimer" and describes multiple complexes including with Hop/piwi,
      sicily/ND-42, Dpit47/Hsp70aa, and Nup358. The IBA annotation to the generic
      protein-containing complex is correct but very general.
    action: ACCEPT
    reason: HSP90 is known to form multiple protein complexes. While the term is generic,
      IBA annotations at this level are acceptable as they reflect the phylogenetic
      inference. More specific complex annotations (GO:0101031, GO:0034663) are captured
      elsewhere.
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: IBA annotation to plasma membrane is supported by phylogenetic inference
      from multiple HSP90 orthologs. Hsp83 was also detected at the plasma membrane
      by HDA (PMID:19317464). Hsp90 has an amphipathic helix that allows membrane
      interaction (PMID:30193096), which could explain plasma membrane localization.
    action: ACCEPT
    reason: Plasma membrane localization is consistent with both the IBA evidence
      from orthologs and the independent HDA evidence from proteomics (PMID:19317464).
      The amphipathic helix-mediated membrane interaction described in PMID:30193096
      provides a mechanistic basis.
    supported_by:
    - reference_id: PMID:30193096
      supporting_text: Hsp90 also has the ability to directly interact with and deform
        membranes via an evolutionarily conserved amphipathic helix
- term:
    id: GO:0005524
    label: ATP binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: ATP binding is a fundamental property of HSP90 family members, mediated
      by the HATPase_c domain. UniProt lists multiple ATP binding residues (positions
      39, 81, 100, 126, 385) and the keyword "ATP-binding." IBA annotation is well
      supported.
    action: ACCEPT
    reason: ATP binding is intrinsic to the HSP90 ATPase domain. Structurally characterized
      across the family.
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: Cytosolic localization of HSP90 family members is well established. IBA
      annotation from multiple orthologs. Consistent with UniProt subcellular location
      annotation to "Cytoplasm" and multiple IDA/HDA annotations to cytoplasm in Drosophila.
    action: ACCEPT
    reason: Cytosol is the primary localization for cytoplasmic HSP90 family members.
      IBA is well supported.
- term:
    id: GO:0050821
    label: protein stabilization
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: HSP90 chaperones stabilize client proteins, preventing their degradation.
      UniProt states Hsp83 "promotes the maturation, structural maintenance and proper
      regulation of specific target proteins." IBA from multiple orthologs. Loss of
      Hsp90 function leads to decreased levels of client proteins such as ND42 and
      NDUFS3 (PMID:23509070), directly demonstrating protein stabilization.
    action: ACCEPT
    reason: Protein stabilization is a core function of HSP90 -- client proteins are
      destabilized and degraded when HSP90 is inhibited. Well supported by phylogenetic
      evidence and direct experimental data in Drosophila.
    supported_by:
    - reference_id: PMID:23509070
      supporting_text: Both NDUFS3 and ND42 are severely down-regulated in sicily
        mutants, whereas other mitochondrial proteins, including Porin (Graham et
        al., 2010) and cytochrome c, are unaltered or slightly increased
    - reference_id: file:DROME/Hsp83/Hsp83-deep-research-falcon.md
      supporting_text: |-
        Hsp83 is best understood as the **cytosolic Hsp90 ATP-dependent chaperone** that promotes **late-stage folding/maturation, stabilization, and activation** of diverse client proteins, especially those central to signaling and development
- term:
    id: GO:0034605
    label: cellular response to heat
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: Hsp83 is a heat shock protein that is upregulated in response to heat
      stress. IBA from multiple orthologs. Consistent with IEP evidence from PMID:16595740
      showing Hsp83 protein levels increase after heat shock. Name itself (Heat shock
      protein 83) reflects this function.
    action: ACCEPT
    reason: Cellular response to heat is a defining characteristic of heat shock proteins.
      IBA supported by expression and functional data in Drosophila.
    supported_by:
    - reference_id: PMID:16595740
      supporting_text: increases in the levels of Hsp83 and DnaJ-1 proteins but not
        in the inducible form of Hsp70 were detected by Western blot analysis
- term:
    id: GO:0051082
    label: unfolded protein binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: GO:0051082 "unfolded protein binding" is proposed for obsoletion. HSP90
      does not simply bind unfolded proteins like holdase chaperones; rather, it acts
      as an ATP-dependent foldase that binds near-native client proteins and assists
      their maturation through conformational change driven by ATP hydrolysis. The
      correct MF term is GO:0140662 "ATP-dependent protein folding chaperone."
    action: MODIFY
    reason: GO:0051082 is proposed for obsoletion and does not accurately describe
      the HSP90 mechanism. HSP90 does not primarily bind unfolded proteins; it binds
      near-native, partially folded client proteins and uses ATP hydrolysis to drive
      their maturation. The replacement term GO:0140662 "ATP-dependent protein folding
      chaperone" precisely captures the molecular function.
    proposed_replacement_terms:
    - id: GO:0140662
      label: ATP-dependent protein folding chaperone
    supported_by:
    - reference_id: PMID:29775584
      supporting_text: the Hsp90 system is required to extend the dwell time of Ago2
        in the open state, which must be transiently primed by the Hsp70 system
- term:
    id: GO:0048471
    label: perinuclear region of cytoplasm
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: IBA annotation to perinuclear region of cytoplasm is supported by phylogenetic
      inference from multiple orthologs. Also supported by direct experimental evidence
      in Drosophila (IDA, PMID:22902557) where Hsp83 was observed in perinuclear region
      via the piRNA pathway work with Shutdown (Shu).
    action: ACCEPT
    reason: Consistent with IBA evidence and directly confirmed by IDA in Drosophila
      (PMID:22902557).
- term:
    id: GO:0000166
    label: nucleotide binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: IEA annotation from UniProtKB keyword mapping (KW-0547 "Nucleotide-binding").
      Hsp83 is indeed an ATP-binding protein with a well-characterized nucleotide
      binding pocket. This is a broader parent term of ATP binding (GO:0005524) which
      is already annotated with IBA evidence.
    action: ACCEPT
    reason: Correct but redundant with the more specific ATP binding annotation. IEA
      annotations at broader levels than IBA are acceptable.
- term:
    id: GO:0005524
    label: ATP binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: IEA annotation for ATP binding from combined automated methods (InterPro:IPR001404,
      InterPro:IPR019805, UniProtKB-KW:KW-0067). Correct and consistent with IBA annotation
      for the same term.
    action: ACCEPT
    reason: Redundant with IBA annotation for the same GO term. Both are correct.
      Hsp83 has a well-characterized HATPase domain.
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  review:
    summary: IEA annotation from UniProt subcellular location vocabulary mapping.
      UniProt annotates Hsp83 subcellular location as "Cytoplasm." Consistent with
      multiple IDA and HDA annotations for cytoplasm.
    action: ACCEPT
    reason: Correct. Cytoplasmic localization is well established by multiple independent
      lines of evidence.
- term:
    id: GO:0006457
    label: protein folding
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  review:
    summary: IEA annotation from InterPro domain mapping (IPR001404, IPR019805). Protein
      folding is the core biological process of HSP90 family. Consistent with IBA
      and other evidence.
    action: ACCEPT
    reason: Correct. Redundant with IBA annotation. InterPro correctly maps the HSP90
      domain to the protein folding process.
- term:
    id: GO:0016887
    label: ATP hydrolysis activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  review:
    summary: IEA annotation from InterPro domain mapping (IPR001404). ATP hydrolysis
      is intrinsic to the HATPase domain of HSP90. Consistent with IBA.
    action: ACCEPT
    reason: Correct. Redundant with IBA annotation. InterPro correctly maps the HSP90
      HATPase domain to ATP hydrolysis activity.
- term:
    id: GO:0051082
    label: unfolded protein binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  review:
    summary: IEA annotation from InterPro domain mapping. GO:0051082 is proposed for
      obsoletion. HSP90 does not function as a holdase chaperone that binds unfolded
      proteins; it is an ATP-dependent foldase that acts on near-native client proteins.
    action: MODIFY
    reason: Same issue as the IBA annotation for this term. GO:0051082 is proposed
      for obsoletion and does not accurately represent the HSP90 mechanism. Should
      be replaced with GO:0140662 "ATP-dependent protein folding chaperone."
    proposed_replacement_terms:
    - id: GO:0140662
      label: ATP-dependent protein folding chaperone
- term:
    id: GO:0101031
    label: protein folding chaperone complex
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  review:
    summary: IEA annotation from ARBA machine learning model (ARBA:ARBA00026483).
      HSP90 forms multiple chaperone complexes. Consistent with IDA evidence from
      PMID:33176138 for the same term.
    action: ACCEPT
    reason: Correct. HSP90 is a core component of protein folding chaperone complexes.
      Consistent with direct experimental evidence in Drosophila.
- term:
    id: GO:0140662
    label: ATP-dependent protein folding chaperone
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  review:
    summary: IEA annotation from InterPro domain mapping (IPR001404). GO:0140662 "ATP-dependent
      protein folding chaperone" is the correct molecular function term for HSP90,
      accurately capturing its ATP-dependent chaperone mechanism. This is the term
      that should replace GO:0051082 across all annotations.
    action: ACCEPT
    reason: This is the most accurate MF term for HSP90 function. HSP90 binds client
      proteins and assists their folding/maturation through ATP hydrolysis-driven
      conformational changes.
    supported_by:
    - reference_id: PMID:29775584
      supporting_text: the Hsp90 system is required to extend the dwell time of Ago2
        in the open state
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:22579285
  review:
    summary: IPI annotation from IntAct based on physical interaction with Nelf-E
      (P92204). PMID:22579285 showed Hsp90 localizes to promoters and stabilizes the
      NELF complex to maintain RNA polymerase II pausing. While the interaction is
      real, "protein binding" is uninformative.
    action: MARK_AS_OVER_ANNOTATED
    reason: The interaction with Nelf-E is likely reflecting Hsp83's chaperone activity
      on NELF complex stabilization. "Protein binding" is too generic and uninformative.
      The chaperone function is better captured by GO:0140662, and the biological
      outcome (gene expression regulation) is a downstream effect of chaperone activity.
    supported_by:
    - reference_id: PMID:22579285
      supporting_text: Hsp90 maintains and optimizes RNA polymerase II pausing via
        stabilization of the negative elongation factor complex (NELF)
- term:
    id: GO:0034663
    label: endoplasmic reticulum chaperone complex
  evidence_type: IPI
  original_reference_id: PMID:22099462
  review:
    summary: IPI annotation based on physical interaction evidence (PMID:22099462),
      with interactors FB:FBgn0038749 and FB:FBgn0289994. PMID:22099462 identifies
      XPORT as a chaperone for TRP and rhodopsin that interacts with Hsp90 in the
      ER/secretory pathway. Hsp83 is primarily a cytoplasmic chaperone, and ER localization
      would be atypical for the cytoplasmic HSP90 (as opposed to ER-resident GRP94/Hsp90B1).
    action: MARK_AS_OVER_ANNOTATED
    reason: |-
      PMID:22099462 shows XPORT (a resident ER/secretory-pathway protein) interacts
      with Hsp90, but the IPI-based CC annotation to an ER chaperone complex
      over-interprets this transient interaction. Falcon deep research confirms
      Hsp83 is the sole CYTOSOLIC Hsp90-family chaperone in D. melanogaster and is
      primarily cytosolic; stable residence in an ER chaperone complex would be
      atypical for the cytoplasmic HSP90 (the ER-resident Hsp90 paralog is GRP94/
      Hsp90B1, encoded separately by Gp93 in flies). The most parsimonious
      interpretation is a transient cytosolic-side interaction of Hsp83 with XPORT
      during client (TRP/Rh1) processing rather than bona fide membership of an ER
      chaperone complex. The chaperone activity itself is better captured by
      GO:0140662 and GO:0101031.
    supported_by:
    - reference_id: PMID:22099462
      supporting_text: XPORT is a resident ER and secretory pathway protein that interacts
        with TRP and Rh1, as well as with Hsp27 and Hsp90
    - reference_id: file:DROME/Hsp83/Hsp83-deep-research-falcon.md
      supporting_text: |-
        Hsp83 is the sole cytosolic Hsp90-family chaperone in *D. melanogaster* and functions as an ATP-dependent molecular chaperone that promotes late-stage folding, maturation, stabilization, and activation of signaling clients.
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  review:
    summary: ISS annotation transferred from human HSP90AA1 (P07900). A minor pool
      of HSP90 has been reported in mitochondria in mammalian cells. Hsp83 interacts
      with Sicily for chaperoning ND42 before mitochondrial import (PMID:23509070),
      but this occurs in the cytoplasm. Mitochondrial localization of the fly protein
      itself is not directly demonstrated.
    action: KEEP_AS_NON_CORE
    reason: Mitochondrial localization is plausible based on mammalian ortholog data
      but not directly demonstrated in Drosophila. The cytoplasmic chaperoning of
      mitochondrial proteins (PMID:23509070) does not require Hsp83 itself to localize
      to mitochondria.
    supported_by:
    - reference_id: PMID:23509070
      supporting_text: Sicily preprotein interacts with cytosolic Hsp90 to chaperone
        the CI subunit, ND42, before mitochondrial import
- term:
    id: GO:0097753
    label: membrane bending
  evidence_type: IDA
  original_reference_id: PMID:30193096
  review:
    summary: IDA annotation based on direct demonstration in PMID:30193096 that Hsp90
      can directly interact with and deform membranes via an evolutionarily conserved
      amphipathic helix. This is a non-chaperone function structurally separated from
      the protein folding activity.
    action: KEEP_AS_NON_CORE
    reason: Membrane bending is a genuine, experimentally validated function of Hsp90
      mediated by its amphipathic helix. However, it is a non-canonical function distinct
      from the core chaperone activity and therefore non-core. The paper explicitly
      states they "structurally separated the Hsp90 membrane-deforming function from
      its well-characterized chaperone activity."
    supported_by:
    - reference_id: PMID:30193096
      supporting_text: Hsp90 also has the ability to directly interact with and deform
        membranes via an evolutionarily conserved amphipathic helix
    - reference_id: PMID:30193096
      supporting_text: we structurally separated the Hsp90 membrane-deforming function
        from its well-characterized chaperone activity
- term:
    id: GO:0098866
    label: multivesicular body fusion to apical plasma membrane
  evidence_type: IMP
  original_reference_id: PMID:30193096
  review:
    summary: IMP annotation from PMID:30193096. The amphipathic helix of Hsp90 promotes
      the fusion of multivesicular bodies (MVBs) with the plasma membrane, enabling
      exosome release. Mutations and drugs that stabilize the open Hsp90 dimer expose
      the helix and allow MVB fusion.
    action: KEEP_AS_NON_CORE
    reason: This is a genuine but non-core function mediated by the non-chaperone
      membrane-deforming activity of Hsp90. Not a typical chaperone function.
    supported_by:
    - reference_id: PMID:30193096
      supporting_text: this amphipathic helix allows exosome release by promoting
        the fusion of multivesicular bodies (MVBs) with the plasma membrane
- term:
    id: GO:0070922
    label: RISC complex assembly
  evidence_type: IGI
  original_reference_id: PMID:29775584
  review:
    summary: IGI annotation from PMID:29775584 with genetic interactors FB:FBgn0037728
      and FB:FBgn0266599. The paper demonstrates that Hsp70/Hsp90 chaperone machinery
      is required for loading small RNAs into Argonaute, a key step in RISC assembly.
      The Hsp90 system captures and stabilizes the open, active form of Ago2.
    action: ACCEPT
    reason: RISC complex assembly is a well-characterized function of the Hsp90 chaperone
      system. Hsp90 is required for conformational activation of Argonaute to enable
      small RNA loading. This is a specific manifestation of its core chaperone function
      on a defined client protein complex.
    supported_by:
    - reference_id: PMID:29775584
      supporting_text: Loading of small RNAs into Argonaute, the core protein in RNA
        silencing, requires the Hsp70/Hsp90 chaperone machinery
    - reference_id: PMID:29775584
      supporting_text: the Hsp90 system is required to extend the dwell time of Ago2
        in the open state
- term:
    id: GO:0070922
    label: RISC complex assembly
  evidence_type: IPI
  original_reference_id: PMID:33176138
  review:
    summary: IPI annotation from PMID:33176138 with interactors FB:FBgn0036020, FB:FBgn0087035,
      and FB:FBgn0262739. PMID:33176138 identifies Cyclophilin 40 as a testis-specialized
      Hsp90 co-chaperone that modulates Ago2-RISC formation. Cyp40 interacts with
      Ago2 through Hsp90 and promotes the build-up of Ago2-bound miRNAs.
    action: ACCEPT
    reason: Consistent with the IGI evidence from PMID:29775584 and with the known
      role of HSP90 in Argonaute maturation and RISC assembly. Additional IPI evidence
      strengthens the annotation.
    supported_by:
    - reference_id: PMID:33176138
      supporting_text: Cyp40 interacts with duplex-incorporating Ago2 through Hsp90
        in vitro and selectively promotes the build-up of Ago2-bound miRNAs
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:31907206
  review:
    summary: IPI annotation from UniProt based on interaction with Morgana/CHORD (Q9VCC0).
      PMID:31907206 showed that Morgana co-purifies with the Hsp90-R2TP-TTT supercomplex.
      This is a typical co-chaperone interaction.
    action: MARK_AS_OVER_ANNOTATED
    reason: '"Protein binding" is uninformative. The interaction with Morgana reflects
      Hsp83''s role as part of the Hsp90-R2TP-TTT chaperone supercomplex. This is
      better captured by the chaperone complex annotations (GO:0101031) and the ATP-dependent
      protein folding chaperone MF term (GO:0140662).'
    supported_by:
    - reference_id: PMID:31907206
      supporting_text: Mora localises to mitotic spindles and co-purifies with the
        Hsp90-R2TP-TTT supercomplex and with additional well-known Hsp90 co-chaperones
- term:
    id: GO:0016887
    label: ATP hydrolysis activity
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  review:
    summary: ISS annotation transferred from human HSP90AA1 (P07900). ATP hydrolysis
      is well established for HSP90 family members. Consistent with IBA evidence for
      the same term.
    action: ACCEPT
    reason: Correct. Redundant with IBA. ATP hydrolysis is a core function of the
      HSP90 family.
- term:
    id: GO:0101031
    label: protein folding chaperone complex
  evidence_type: IDA
  original_reference_id: PMID:33176138
  review:
    summary: IDA annotation from PMID:33176138 directly demonstrating Hsp83 as part
      of a protein folding chaperone complex. PMID:33176138 shows Hsp90 machinery
      acts as chaperone complex for Ago2 loading during RISC assembly. HSP90 forms
      complexes with co-chaperones (Hop, p23, Cdc37, Cyp40, etc.) to constitute chaperone
      machinery.
    action: ACCEPT
    reason: HSP90 is a core component of chaperone complexes. IDA evidence directly
      confirms this in Drosophila. Consistent with UniProt subunit annotations describing
      multiple Hsp83-containing complexes.
    supported_by:
    - reference_id: PMID:33176138
      supporting_text: In gene silencing, Hsp90 chaperone machinery assists Argonaute
        (Ago) binding and unwinding of silencing small RNA (sRNA) duplexes
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:23509070
  review:
    summary: IPI annotation from UniProt based on interaction with Sicily (P91929)
      and ND-42/NDUFA10 (Q9VYS5). PMID:23509070 showed Sicily is a cytosolic chaperone
      for a mitochondrial Complex I subunit, and Hsp83 forms a complex with Sicily
      and ND42. Hsp90 binds to Sicily directly and coimmunoprecipitates ND42 only
      when Sicily is coexpressed.
    action: MARK_AS_OVER_ANNOTATED
    reason: '"Protein binding" is uninformative. The interaction with Sicily reflects
      Hsp83''s chaperone function in chaperoning ND42 before mitochondrial import.
      Better captured by the ATP-dependent protein folding chaperone MF term (GO:0140662)
      and the protein stabilization BP term (GO:0050821).'
    supported_by:
    - reference_id: PMID:23509070
      supporting_text: Hsp90 binds to Sicily in an in vitro co-IP assay
- term:
    id: GO:0002052
    label: positive regulation of neuroblast proliferation
  evidence_type: IMP
  original_reference_id: PMID:30245208
  review:
    summary: IMP annotation from PMID:30245208. Hsp83 is both necessary and sufficient
      for neural stem cell reactivation by promoting the activation of InR pathway
      in larval brains. This is a downstream pleiotropic effect of Hsp83 chaperone
      function on signaling clients.
    action: KEEP_AS_NON_CORE
    reason: This is a downstream developmental phenotype of Hsp83 function, likely
      mediated through its role in insulin receptor signaling (same paper provides
      insulin receptor binding annotation). Non-core pleiotropic effect.
    supported_by:
    - reference_id: PMID:30245208
      supporting_text: Hsp83 is both necessary and sufficient for NSC reactivation
        by promoting the activation of InR pathway in larval brains in the presence
        of dietary amino acids
- term:
    id: GO:0005158
    label: insulin receptor binding
  evidence_type: IDA
  original_reference_id: PMID:30245208
  review:
    summary: IDA annotation from PMID:30245208 demonstrating direct binding of Hsp83
      to the insulin receptor. Both Hsp83 and its co-chaperone Cdc37 physically associate
      with InR. HSP90 is known to chaperone receptor tyrosine kinases in other systems.
      This likely reflects HSP90's general role in chaperoning kinase clients.
    action: KEEP_AS_NON_CORE
    reason: Insulin receptor binding is consistent with HSP90's well-known role as
      a kinase chaperone, but it represents a specific client interaction rather than
      a core molecular function. The core function is the ATP-dependent protein folding
      chaperone activity.
    supported_by:
    - reference_id: PMID:30245208
      supporting_text: Both Hsp83 and its co-chaperone Cdc37 physically associate
        with InR
- term:
    id: GO:0046628
    label: positive regulation of insulin receptor signaling pathway
  evidence_type: IGI
  original_reference_id: PMID:30245208
  review:
    summary: IGI annotation from PMID:30245208 with genetic interactor FB:FBgn0283499.
      Hsp83 positively regulates insulin receptor signaling, consistent with its role
      in chaperoning the insulin receptor.
    action: KEEP_AS_NON_CORE
    reason: Downstream pleiotropic effect of Hsp83 chaperone function on insulin signaling.
      Non-core but experimentally supported.
    supported_by:
    - reference_id: PMID:30245208
      supporting_text: Hsp83 is both necessary and sufficient for NSC reactivation
        by promoting the activation of InR pathway in larval brains in the presence
        of dietary amino acids
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: HDA
  original_reference_id: PMID:26896675
  review:
    summary: HDA annotation from a genome-wide protein localization study (PMID:26896675)
      using GFP-tagged fosmid transgenes in Drosophila. Cytoplasmic localization is
      consistent with all other evidence.
    action: ACCEPT
    reason: Cytoplasm is the primary localization for Hsp83. Confirmed by multiple
      independent methods.
    supported_by:
    - reference_id: PMID:26896675
      supporting_text: A genome-wide resource for the analysis of protein localisation
        in Drosophila
- term:
    id: GO:0030911
    label: TPR domain binding
  evidence_type: IPI
  original_reference_id: PMID:27979731
  review:
    summary: 'IPI annotation from PMID:27979731 based on interaction of Hsp83 with
      the TPR domain of Nup358. The C-terminal MEEVD motif of HSP90 is a well-characterized
      TPR repeat-binding motif (UniProt: "The TPR repeat-binding motif mediates interaction
      with TPR repeat-containing proteins"). The interaction with Nup358 TPR domain
      facilitates nuclear import of Met, the juvenile hormone receptor.'
    action: ACCEPT
    reason: TPR domain binding is a core molecular function of HSP90 family members,
      mediated by the conserved C-terminal MEEVD motif. This is how HSP90 interacts
      with many co-chaperones (Hop, CHIP, Tom70, etc.) and other TPR-containing proteins.
    supported_by:
    - reference_id: PMID:27979731
      supporting_text: a tetratricopeptide repeat (TPR) domain at the N-terminal end
        of Nup358 interacts with Hsp83 and is indispensable for Met nuclear localization
    - reference_id: file:DROME/Hsp83/Hsp83-deep-research-falcon.md
      supporting_text: |-
        Key named regulators include **Cdc37** (kinase client recruitment), **p23**, and **Aha1**, as well as **TPR-domain** proteins such as **Hop** that bind the conserved **MEEVD** C-terminal motif typical of cytosolic Hsp90s
- term:
    id: GO:0006457
    label: protein folding
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  review:
    summary: ISS annotation transferred from yeast HSP82 (P15108). Protein folding
      is well established for HSP90 family. Consistent with IBA and IEA evidence.
    action: ACCEPT
    reason: Correct. Redundant with IBA and IEA. Protein folding is the core biological
      process.
- term:
    id: GO:0034605
    label: cellular response to heat
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  review:
    summary: ISS annotation transferred from yeast HSP82 (P15108). Cellular response
      to heat is well established for heat shock proteins. Consistent with IBA evidence.
    action: ACCEPT
    reason: Correct. Redundant with IBA. Heat shock response is a defining feature
      of HSP90 family.
- term:
    id: GO:0043248
    label: proteasome assembly
  evidence_type: IDA
  original_reference_id: PMID:15946124
  review:
    summary: IDA annotation from PMID:15946124. Hsp82 (Hsp83) was identified by mass
      spectrometry as the main Rpn10/p54-interacting protein after Zn2+-induced proteasome
      disassembly, suggesting a role in reassembly of the 26S proteasome.
    action: KEEP_AS_NON_CORE
    reason: The evidence shows Hsp83 interacts with Rpn10 after proteasome disassembly,
      suggesting a role in reassembly. This is consistent with HSP90's general chaperone
      function applied to proteasome components, but represents a specific client
      relationship rather than a core function.
    supported_by:
    - reference_id: PMID:15946124
      supporting_text: Hsp82 (heat-shock protein 82) has been identified by MS as
        the main Rpn10/p54-interacting protein, suggesting its role in the reassembly
        of the 26 S proteasome after Zn2+ removal
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: HDA
  original_reference_id: PMID:24292889
  review:
    summary: HDA annotation from PMID:24292889 (Ube3a proteasomal shuttle Rpn10 study).
      Cytoplasmic localization detected as part of a high-throughput study. Consistent
      with other evidence.
    action: ACCEPT
    reason: Cytoplasm localization is well established. Additional HDA evidence.
    supported_by:
    - reference_id: PMID:24292889
      supporting_text: Overexpression of these proteins leads to an enhanced accumulation
        of ubiquitinated proteins, further supporting the biochemical evidence of interaction
        obtained in neuronal cells
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: HDA
  original_reference_id: PMID:19317464
  review:
    summary: HDA annotation from PMID:19317464 (LOPIT subcellular proteomics study
      in Drosophila embryos). Plasma membrane localization detected in this systematic
      study. Consistent with IBA annotation and the amphipathic helix-mediated membrane
      interaction (PMID:30193096).
    action: ACCEPT
    reason: Plasma membrane localization supported by independent proteomics evidence
      and consistent with IBA and the membrane-deforming function.
    supported_by:
    - reference_id: PMID:19317464
      supporting_text: we apply LOPIT, a mass-spectrometry based technique that simultaneously
        maps proteins to specific subcellular compartments, to Drosophila embryos
- term:
    id: GO:0051082
    label: unfolded protein binding
  evidence_type: IDA
  original_reference_id: PMID:18344983
  review:
    summary: IDA annotation from PMID:18344983. This paper is primarily about NMNAT
      as a chaperone, not about Hsp83 directly. The paper shows that NMNAT "displays
      chaperone function both in biochemical assays and cultured cells" and compares
      it to Hsp70. Hsp83 is mentioned as a control or comparison. Regardless, GO:0051082
      is proposed for obsoletion and the term does not correctly describe HSP90 function.
      HSP90 is an ATP-dependent foldase, not a holdase.
    action: MODIFY
    reason: GO:0051082 is proposed for obsoletion. The evidence in PMID:18344983 is
      primarily about NMNAT chaperone function, with Hsp83 as a comparison. The correct
      term for Hsp83 molecular function is GO:0140662 "ATP-dependent protein folding
      chaperone."
    proposed_replacement_terms:
    - id: GO:0140662
      label: ATP-dependent protein folding chaperone
    supported_by:
    - reference_id: PMID:18344983
      supporting_text: NMNAT displays chaperone function both in biochemical assays
        and cultured cells, and it shares significant structural similarity with known
        chaperones
- term:
    id: GO:0008285
    label: negative regulation of cell population proliferation
  evidence_type: IMP
  original_reference_id: PMID:24086162
  review:
    summary: IMP annotation from PMID:24086162. Hsp83 mutation results in increased
      E2F-dependent transcription and ectopic cell proliferation in pupal tissues,
      demonstrating that Hsp83 is required for proper cell cycle exit. The paper proposes
      Cdh1/Fzr (APC/C activating subunit) is a client of Hsp83. Thus Hsp83 indirectly
      promotes cell cycle exit by chaperoning APC/C components.
    action: KEEP_AS_NON_CORE
    reason: This is a downstream phenotypic consequence of Hsp83 chaperone function
      on cell cycle regulators (APC/C components). The paper proposes "Cdh1/Fzr is
      a client protein of Hsp83." This is a pleiotropic effect of the core chaperone
      function, not a core function itself.
    supported_by:
    - reference_id: PMID:24086162
      supporting_text: Mutation of Hsp83, the Drosophila homolog of mammalian Hsp90,
        results in increased E2F-dependent transcription and ectopic cell proliferation
        in pupal tissues at a time when neighboring wild-type cells are postmitotic
    - reference_id: PMID:24086162
      supporting_text: we propose that Cdh1/Fzr is a client protein of Hsp83
    - reference_id: file:DROME/Hsp83/Hsp83-deep-research-falcon.md
      supporting_text: |-
        In Hsp83(6-55) mutant clones, E2F-dependent transcription increases and cells show ectopic S phase and mitosis after neighboring cells have exited the cell cycle
- term:
    id: GO:0048471
    label: perinuclear region of cytoplasm
  evidence_type: IDA
  original_reference_id: PMID:22902557
  review:
    summary: IDA annotation from PMID:22902557. This paper studies the cochaperone
      Shutdown and piRNA biogenesis. Using a genomic GFP-tagged Hsp83 construct, the
      authors show that Hsp83 is enriched in a peri-nuclear rim in wild-type nurse
      cells, potentially reflecting nuage accumulation. Hsp83 colocalizes with unloaded
      AGO3 in cytoplasmic foci when piRNA biogenesis is disrupted.
    action: ACCEPT
    reason: Perinuclear region localization is directly demonstrated by IDA using
      GFP-tagged Hsp83 and is consistent with IBA evidence and the known role of Hsp83
      in piRNA biogenesis in germline nuage.
    supported_by:
    - reference_id: PMID:22902557
      supporting_text: Hsp83 was enriched in a peri-nuclear rim, potentially reflecting
        nuage accumulation
- term:
    id: GO:0005705
    label: polytene chromosome interband
  evidence_type: IDA
  original_reference_id: PMID:19144915
  review:
    summary: IDA annotation from PMID:19144915. This paper shows a direct molecular
      interaction between Hsp90 and Trithorax, and that Hsp90 cooperates with Trx
      at chromatin for maintaining the active expression state of targets like Hox
      genes. Polytene chromosome interband localization is consistent with the chromatin-binding
      function of Hsp90.
    action: ACCEPT
    reason: PMID:19144915 demonstrates Hsp90 interacts with Trithorax at chromatin
      to maintain active gene expression. Polytene chromosome interband localization
      is consistent with this chromatin-associated function and with the finding from
      PMID:22579285 that Hsp90 localizes to promoters.
    supported_by:
    - reference_id: PMID:19144915
      supporting_text: Hsp90 cooperates with Trx at chromatin for maintaining the
        active expression state of targets like the Hox genes
    additional_reference_ids:
    - PMID:22579285
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IDA
  original_reference_id: PMID:19144915
  review:
    summary: IDA annotation from PMID:19144915. Cytoplasmic localization is consistent
      with all other evidence.
    action: ACCEPT
    reason: Cytoplasm localization is independently confirmed by many other studies.
      This annotation is redundant but correct.
    supported_by:
    - reference_id: PMID:19144915
      supporting_text: Molecular chaperone heat-shock protein 90 kDa (Hsp90) is known
        to facilitate the conformational maturation of a diverse range of proteins
        involved in different signal transduction pathways during development
- term:
    id: GO:0009631
    label: cold acclimation
  evidence_type: IEP
  original_reference_id: PMID:16313561
  review:
    summary: IEP annotation from PMID:16313561. Microarray analysis showed Hsp83 transcript
      was differentially expressed after cold hardening treatment (0 C for 2 h followed
      by recovery). The evidence is expression-based only (IEP), and does not demonstrate
      a direct functional role.
    action: KEEP_AS_NON_CORE
    reason: Based solely on expression evidence (IEP). Transcript upregulation during
      cold hardening does not prove a direct role in cold acclimation. However, Hsp83
      may contribute to protein homeostasis under cold stress. Keeping as non-core
      due to indirect evidence.
    supported_by:
    - reference_id: PMID:16313561
      supporting_text: stress proteins, including Hsp23, Hsp26, Hsp83 and Frost as
        well as membrane-associated proteins may contribute to the cold hardening
        response
- term:
    id: GO:0009408
    label: response to heat
  evidence_type: IEP
  original_reference_id: PMID:16595740
  review:
    summary: IEP annotation from PMID:16595740. Hsp83 protein levels were shown to
      increase after heat shock by Western blot analysis, even in a heat shock factor
      mutant (hsf4). As a constitutively expressed heat shock protein, Hsp83 upregulation
      during heat stress provides thermoprotection at synapses.
    action: ACCEPT
    reason: |-
      While IEP is weaker evidence, the response to heat is fundamental to heat
      shock proteins. The name "Heat shock protein 83" itself reflects this. The more
      specific term "cellular response to heat" (GO:0034605) is also annotated with
      IBA and ISS evidence. Falcon deep research adds an important nuance: Hsp83 is
      largely a constitutive proteostasis factor and is NOT transcriptionally induced
      in every proteotoxic stress state (e.g., in a 2023 larval fat body study Hsp83
      and Gp93 did not change despite induction of Hsp70/Hsp40-class genes). The
      response-to-heat annotation remains valid (protein levels do rise after heat
      shock per PMID:16595740), but it reflects a partially constitutive, context-
      dependent thermoprotective role rather than a universally inducible response.
    supported_by:
    - reference_id: PMID:16595740
      supporting_text: the compensatory upregulation of constitutively expressed Hsps,
        in the absence of the synthesis of the major inducible Hsp, Hsp70, could still
        provide substantial thermoprotection
    - reference_id: file:DROME/Hsp83/Hsp83-deep-research-falcon.md
      supporting_text: |-
        A 2023 Nature Communications study in Drosophila larval fat body found that **Nacα reduction activates a heat shock response**, with upregulation of Hsp70/Hsp40 class genes and oxidative stress markers, but **Hsp83 (and another Hsp90-family gene Gp93) did not change** in that context (qRT-PCR, n=4 batches)
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IDA
  original_reference_id: PMID:19101615
  review:
    summary: IDA annotation from PMID:19101615. Hsp90 and Cup co-localize in the cytoplasm
      of developing germ-line cells within the germarium.
    action: ACCEPT
    reason: Cytoplasmic localization directly demonstrated during oogenesis. Consistent
      with all other cytoplasm annotations.
    supported_by:
    - reference_id: PMID:19101615
      supporting_text: Hsp90 and Cup co-localize in the cytoplasm of the developing
        germ-line cells within the germarium
- term:
    id: GO:0048477
    label: oogenesis
  evidence_type: IGI
  original_reference_id: PMID:19101615
  review:
    summary: IGI annotation from PMID:19101615 with genetic interactor Cup (FB:FBgn0000392).
      Lowering Hsp90 activity enhances oogenesis alterations linked to diverse cup
      mutant alleles, demonstrating a genetic interaction in oogenesis. Hsp90 is a
      component of the cap-binding complex and interacts with the translational repressor
      Cup during oogenesis.
    action: KEEP_AS_NON_CORE
    reason: Oogenesis involvement is a pleiotropic consequence of Hsp83 chaperone
      function during development. The paper shows Hsp90 participates in translational
      regulation during oogenesis via the cap-binding complex. This is a downstream
      developmental role, not a core function.
    supported_by:
    - reference_id: PMID:19101615
      supporting_text: lowering Hsp90 activity enhances the oogenesis alterations
        linked to diverse cup mutant alleles
    - reference_id: file:DROME/Hsp83/Hsp83-deep-research-falcon.md
      supporting_text: |-
        Hsp83 also contributes to female fertility, oogenesis, and maternal RNA regulation. It interacts with the translational regulator Cup during oogenesis, localizes maternal transcripts, and affects *nanos* mRNA localization, linking Hsp83 to anterior–posterior patterning in embryos.
- term:
    id: GO:0019094
    label: pole plasm mRNA localization
  evidence_type: IMP
  original_reference_id: PMID:17565952
  review:
    summary: IMP annotation from PMID:17565952. Genetic approaches show that Hsp83/Hsp90
      is a localization factor for nanos and pgc mRNAs. When Hsp90 function is partially
      compromised, nanos and pgc mRNA localization is disrupted while other pole plasm
      components are unaffected. The mechanism appears to involve Hsp90 chaperoning
      LKB1 kinase (for pgc) and other partners (for nos).
    action: KEEP_AS_NON_CORE
    reason: This is a specific developmental role of Hsp83 in mRNA localization during
      embryogenesis, likely mediated through its chaperone function on LKB1 kinase
      and other clients. Non-core pleiotropic effect.
    supported_by:
    - reference_id: PMID:17565952
      supporting_text: the Hsp90 chaperone (encoded by Hsp83 in Drosophila) is a localization
        factor for two mRNAs, nanos and pgc
    - reference_id: PMID:17565952
      supporting_text: levels of the LKB1 kinase are reduced in Hsp83 mutant egg chambers
    - reference_id: file:DROME/Hsp83/Hsp83-deep-research-falcon.md
      supporting_text: |-
        It interacts with the translational regulator Cup during oogenesis, localizes maternal transcripts, and affects *nanos* mRNA localization, linking Hsp83 to anterior–posterior patterning in embryos.
- term:
    id: GO:0005813
    label: centrosome
  evidence_type: IDA
  original_reference_id: PMID:10716925
  review:
    summary: IDA annotation from PMID:10716925. Mass spectrometry analysis of immunoisolated
      Drosophila centrosomes identified Hsp83. The association persists after microtubule
      depolymerizing drug treatment, indicating Hsp90 is a core centrosomal component.
    action: ACCEPT
    reason: Directly demonstrated by mass spectrometry of purified centrosomes and
      confirmed to be a core centrosomal component that persists after microtubule
      depolymerization.
    supported_by:
    - reference_id: PMID:10716925
      supporting_text: a fraction of the total Hsp90 pool is localized at the centrosome
        throughout the cell cycle
    - reference_id: PMID:10716925
      supporting_text: This association between Hsp90 and the centrosome can be observed
        in purified centrosomes and after treatment with microtubule depolymerizing
        drugs, two criteria normally used to define core centrosomal components
- term:
    id: GO:0006457
    label: protein folding
  evidence_type: TAS
  original_reference_id: PMID:10716925
  review:
    summary: TAS annotation from PMID:10716925 which describes Hsp83 as "a member
      of the highly conserved Hsp90 family including chaperones known to maintain
      the activity of many proteins." The protein folding function is stated as established
      fact in the publication.
    action: ACCEPT
    reason: Correct. Protein folding is the core function. Redundant with IBA, IEA,
      and ISS evidence.
    supported_by:
    - reference_id: PMID:10716925
      supporting_text: a member of the highly conserved Hsp90 family including chaperones
        known to maintain the activity of many proteins
- term:
    id: GO:0007098
    label: centrosome cycle
  evidence_type: IMP
  original_reference_id: PMID:10716925
  review:
    summary: IMP annotation from PMID:10716925. Disruption of Hsp90 function by mutations
      in Hsp83 or geldanamycin treatment results in abnormal centrosome separation
      and maturation, aberrant spindles, and impaired chromosome segregation.
    action: KEEP_AS_NON_CORE
    reason: Centrosome cycle involvement is a downstream consequence of Hsp83 chaperone
      function on centrosome client proteins. Hsp90 is required for proper centrosome
      function, but this is a pleiotropic effect of its core chaperone activity.
    supported_by:
    - reference_id: PMID:10716925
      supporting_text: Disruption of Hsp90 function by mutations in the Drosophila
        gene or treatment of mammalian cells with the Hsp90 inhibitor geldanamycin,
        results in abnormal centrosome separation and maturation, aberrant spindles
        and impaired chromosome segregation
- term:
    id: GO:0045187
    label: regulation of circadian sleep/wake cycle, sleep
  evidence_type: IMP
  original_reference_id: PMID:12015603
  review:
    summary: IMP annotation from PMID:12015603. Flies carrying a mutation for Hsp83
      showed exaggerated homeostatic sleep response and died after sleep deprivation,
      demonstrating that Hsp83 plays a protective role in sleep homeostasis.
    action: KEEP_AS_NON_CORE
    reason: Sleep regulation is a pleiotropic downstream effect. Hsp83 mutants show
      exaggerated homeostatic response to sleep deprivation, but this likely reflects
      a general stress-protective role rather than a direct sleep-regulatory function.
    supported_by:
    - reference_id: PMID:12015603
      supporting_text: flies carrying a mutation for the heat-shock protein Hsp83
        (Hsp83(08445)) showed exaggerated homeostatic response and died after sleep
        deprivation
- term:
    id: GO:0045187
    label: regulation of circadian sleep/wake cycle, sleep
  evidence_type: TAS
  original_reference_id: PMID:12486704
  review:
    summary: TAS annotation from PMID:12486704. This is a review article discussing
      sleep research in Drosophila and mouse, referencing the genetic approaches that
      identified Hsp83 mutants with sleep phenotypes.
    action: KEEP_AS_NON_CORE
    reason: Consistent with the IMP annotation from PMID:12015603 for the same term.
      Sleep regulation is a non-core pleiotropic effect.
    supported_by:
    - reference_id: PMID:12486704
      supporting_text: studies in both the mouse and fly have begun to reveal tantalizing
        suggestions about the underlying principles that regulate sleep homeostasis
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO
    terms
  findings: []
- id: GO_REF:0000024
  title: Manual transfer of experimentally-verified manual GO annotation data to orthologs
    by curator judgment of sequence similarity
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000043
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping
  findings: []
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location
    vocabulary mapping, accompanied by conservative changes to GO terms applied by
    UniProt
  findings: []
- id: GO_REF:0000117
  title: Electronic Gene Ontology annotations created by ARBA machine learning models
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:10716925
  title: Hsp90 is a core centrosomal component and is required at different stages
    of the centrosome cycle in Drosophila and vertebrates.
  findings:
  - statement: Hsp83 identified by mass spectrometry in purified Drosophila centrosomes
    supporting_text: "One of the proteins identified is Hsp83, a member of the highly conserved Hsp90 family including chaperones known to maintain the activity of many proteins"
  - statement: A fraction of total Hsp90 pool is localized at the centrosome throughout the cell cycle
    supporting_text: "a fraction of the total Hsp90 pool is localized at the centrosome throughout the cell cycle at different stages of development in Drosophila and vertebrates"
  - statement: Disruption of Hsp90 function causes abnormal centrosome separation and maturation
    supporting_text: "Disruption of Hsp90 function by mutations in the Drosophila gene or treatment of mammalian cells with the Hsp90 inhibitor geldanamycin, results in abnormal centrosome separation and maturation, aberrant spindles and impaired chromosome segregation"
- id: PMID:12015603
  title: Stress response genes protect against lethal effects of sleep deprivation
    in Drosophila.
  findings:
  - statement: Hsp83 mutants show exaggerated homeostatic sleep response and die after sleep deprivation
    supporting_text: "flies carrying a mutation for the heat-shock protein Hsp83 (Hsp83(08445)) showed exaggerated homeostatic response and died after sleep deprivation"
  - statement: Heat-shock genes protect against lethal effects of sleep deprivation
    supporting_text: "activating heat-shock genes before sleep deprivation rescued cyc(01) flies from its lethal effects"
- id: PMID:12486704
  title: 'Perchance to dream: solving the mystery of sleep through genetic analysis.'
  findings: []
- id: PMID:15946124
  title: Zn2+-induced reversible dissociation of subunit Rpn10/p54 of the Drosophila
    26 S proteasome.
  findings:
  - statement: Hsp82 identified by MS as the main Rpn10/p54-interacting protein after proteasome disassembly
    supporting_text: "Hsp82 (heat-shock protein 82) has been identified by MS as the main Rpn10/p54-interacting protein, suggesting its role in the reassembly of the 26 S proteasome after Zn2+ removal"
  - statement: Suggests Hsp83 role in reassembly of 26S proteasome
    supporting_text: "removal of Zn2+ is followed by reassociation of subunit Rpn10/p54 to the RP, reassembly of the 26 S proteasome and resumption of the peptidase activity"
- id: PMID:16313561
  title: Cold hardening and transcriptional change in Drosophila melanogaster.
  findings:
  - statement: Hsp83 transcript upregulated after cold hardening treatment
    supporting_text: "stress proteins, including Hsp23, Hsp26, Hsp83 and Frost as well as membrane-associated proteins may contribute to the cold hardening response"
- id: PMID:16595740
  title: Thermoprotection of synaptic transmission in a Drosophila heat shock factor
    mutant is accompanied by increased expression of Hsp83 and DnaJ-1.
  findings:
  - statement: Hsp83 protein levels increase after heat shock even in hsf4 mutants
    supporting_text: "increases in the levels of Hsp83 and DnaJ-1 proteins but not in the inducible form of Hsp70 were detected by Western blot analysis"
  - statement: Compensatory upregulation of constitutive Hsps provides thermoprotection
    supporting_text: "the compensatory upregulation of constitutively expressed Hsps, in the absence of the synthesis of the major inducible Hsp, Hsp70, could still provide substantial thermoprotection"
- id: PMID:17565952
  title: The molecular chaperone Hsp90 is required for mRNA localization in Drosophila
    melanogaster embryos.
  findings:
  - statement: Hsp83/Hsp90 is a localization factor for nanos and pgc mRNAs
    supporting_text: "the Hsp90 chaperone (encoded by Hsp83 in Drosophila) is a localization factor for two mRNAs, nanos and pgc"
  - statement: LKB1 kinase levels reduced in Hsp83 mutant egg chambers
    supporting_text: "levels of the LKB1 kinase are reduced in Hsp83 mutant egg chambers"
- id: PMID:18344983
  title: NAD synthase NMNAT acts as a chaperone to protect against neurodegeneration.
  findings:
  - statement: NMNAT displays chaperone function similar to heat-shock proteins
    supporting_text: "NMNAT displays chaperone function both in biochemical assays and cultured cells, and it shares significant structural similarity with known chaperones"
  - statement: Hsp83 used as comparison/control in chaperone assays
    supporting_text: "it is upregulated in the brain upon overexpression of poly-glutamine expanded protein and recruited with the chaperone Hsp70 into protein aggregates"
- id: PMID:19101615
  title: The molecular chaperone Hsp90 is a component of the cap-binding complex and
    interacts with the translational repressor Cup during Drosophila oogenesis.
  findings:
  - statement: Hsp90 isolated as component of cap-binding complex
    supporting_text: "isolated the product of the Hsp83 gene, the evolutionarily conserved chaperone Hsp90, as a specific component of the cap-binding complex"
  - statement: Hsp90 interacts with translational repressor Cup
    supporting_text: "Hsp90 interacts in vitro with the translational repressor Cup"
  - statement: Hsp83 and cup interact genetically in oogenesis
    supporting_text: "lowering Hsp90 activity enhances the oogenesis alterations linked to diverse cup mutant alleles"
  - statement: Hsp90 and Cup co-localize in cytoplasm of germline cells
    supporting_text: "Hsp90 and Cup co-localize in the cytoplasm of the developing germ-line cells within the germarium"
- id: PMID:19144915
  title: Trithorax requires Hsp90 for maintenance of active chromatin at sites of gene
    expression.
  findings:
  - statement: Hsp90 interacts directly with Trithorax and cooperates at chromatin for maintaining active expression
    supporting_text: "Hsp90 cooperates with Trx at chromatin for maintaining the active expression state of targets like the Hox genes"
  - statement: Pharmacological inhibition of Hsp90 results in degradation of Trx and down-regulation of homeotic gene expression
    supporting_text: "Pharmacological inhibition of Hsp90 results in degradation of Trx and a concomitant down-regulation of homeotic gene expression"
- id: PMID:19317464
  title: Mapping organelle proteins and protein complexes in Drosophila melanogaster.
  findings:
  - statement: LOPIT proteomics maps Hsp83 subcellular distribution in Drosophila embryos
    supporting_text: "we apply LOPIT, a mass-spectrometry based technique that simultaneously maps proteins to specific subcellular compartments, to Drosophila embryos"
- id: PMID:22099462
  title: XPORT-dependent transport of TRP and rhodopsin.
  findings:
  - statement: XPORT interacts with TRP, Rh1, Hsp27, and Hsp90 as part of ER chaperone function
    supporting_text: "XPORT is a resident ER and secretory pathway protein that interacts with TRP and Rh1, as well as with Hsp27 and Hsp90"
  - statement: XPORT promotes targeting of TRP to the membrane in Drosophila S2 cells
    supporting_text: "XPORT promotes the targeting of TRP to the membrane in Drosophila S2 cells"
- id: PMID:22579285
  title: Hsp90 globally targets paused RNA polymerase to regulate gene expression
    in response to environmental stimuli.
  findings:
  - statement: Hsp90 localizes to promoters of many genes
    supporting_text: "It localizes near promoters of many coding and noncoding genes including microRNAs"
  - statement: Hsp90 stabilizes NELF complex to maintain RNA Pol II pausing
    supporting_text: "Hsp90 maintains and optimizes RNA polymerase II pausing via stabilization of the negative elongation factor complex (NELF)"
  - statement: Hsp90 inhibition leads to upregulation of target genes
    supporting_text: "Inhibition of Hsp90 leads to upregulation of target genes"
- id: PMID:22902557
  title: The cochaperone shutdown defines a group of biogenesis factors essential for
    all piRNA populations in Drosophila.
  findings:
  - statement: Hsp83 interacts with cochaperone Shutdown (Shu)
    supporting_text: "unloaded AGO3 that localizes to cytoplasmic foci interacts with Hsp83"
  - statement: Required for piRNA biogenesis
    supporting_text: "our genetic and cell biological data point toward an important role for the Hsp83 machinery in piRNA biogenesis"
  - statement: Hsp83 enriched in peri-nuclear rim in wild-type nurse cells
    supporting_text: "Hsp83 was enriched in a peri-nuclear rim, potentially reflecting nuage accumulation"
- id: PMID:23509070
  title: The C8ORF38 homologue Sicily is a cytosolic chaperone for a mitochondrial
    complex I subunit.
  findings:
  - statement: Hsp83 forms complex with Sicily and ND42 for mitochondrial protein chaperoning
    supporting_text: "Sicily preprotein interacts with cytosolic Hsp90 to chaperone the CI subunit, ND42, before mitochondrial import"
  - statement: Hsp90 binds to Sicily directly and coimmunoprecipitates ND42 only when Sicily is coexpressed
    supporting_text: "Hsp90 binds to Sicily in an in vitro co-IP assay"
  - statement: Loss of Hsp90 leads to decreased levels of Sicily and CI subunits in vivo
    supporting_text: "flies expressing Hsp90 RNAi #1 exhibit severely decreased levels of Sicily, ND42, and NDUFS3 compared with controls"
- id: PMID:24086162
  title: The molecular chaperone Hsp90 is required for cell cycle exit in Drosophila
    melanogaster.
  findings:
  - statement: Hsp83 mutation causes increased E2F transcription and ectopic cell proliferation
    supporting_text: "Mutation of Hsp83, the Drosophila homolog of mammalian Hsp90, results in increased E2F-dependent transcription and ectopic cell proliferation in pupal tissues at a time when neighboring wild-type cells are postmitotic"
  - statement: APC/C targets accumulate in Hsp83 mutant cells
    supporting_text: "these Hsp83 mutant cells have increased Cyclin/Cdk activity and accumulate proteins normally targeted for proteolysis by the anaphase-promoting complex/cyclosome (APC/C)"
  - statement: Cdh1/Fzr proposed as an Hsp83 client protein
    supporting_text: "we propose that Cdh1/Fzr is a client protein of Hsp83"
- id: PMID:24292889
  title: Ube3a, the E3 ubiquitin ligase causing Angelman syndrome and linked to autism,
    regulates protein homeostasis through the proteasomal shuttle Rpn10.
  findings: []
- id: PMID:26896675
  title: A genome-wide resource for the analysis of protein localisation in Drosophila.
  findings:
  - statement: Genome-wide GFP tagging resource for protein localization
    supporting_text: "a genome-wide fosmid library of 10000 GFP-tagged clones, comprising tagged genes and most of their regulatory information"
- id: PMID:27979731
  title: "Nucleoporin Nup358 facilitates nuclear import of Methoprene-tolerant (Met)\
    \ in an importin \u03B2- and Hsp83-dependent manner."
  findings:
  - statement: Nup358 TPR domain interacts with Hsp83
    supporting_text: "a tetratricopeptide repeat (TPR) domain at the N-terminal end of Nup358 interacts with Hsp83 and is indispensable for Met nuclear localization"
  - statement: Interaction required for nuclear import of Met (JH receptor)
    supporting_text: "Nup358 facilitates JH-induced Met nuclear transport in a manner dependent on importin \u03B2 and Hsp83"
- id: PMID:29775584
  title: Conformational Activation of Argonaute by Distinct yet Coordinated Actions
    of the Hsp70 and Hsp90 Chaperone Systems.
  findings:
  - statement: Hsp90 system captures and stabilizes the open active form of Ago2
    supporting_text: "the Hsp90 system is required to extend the dwell time of Ago2 in the open state"
  - statement: Required for small RNA loading into Argonaute
    supporting_text: "Loading of small RNAs into Argonaute, the core protein in RNA silencing, requires the Hsp70/Hsp90 chaperone machinery"
  - statement: Hsp70 system expands structural ensembles, Hsp90 stabilizes active form
    supporting_text: "the Hsp70 system expands the structural ensembles of Ago2 and the Hsp90 system captures and stabilizes the active form"
- id: PMID:30193096
  title: Hsp90 Mediates Membrane Deformation and Exosome Release.
  findings:
  - statement: Hsp90 deforms membranes via amphipathic helix
    supporting_text: "Hsp90 also has the ability to directly interact with and deform membranes via an evolutionarily conserved amphipathic helix"
  - statement: Membrane function structurally separated from chaperone activity
    supporting_text: "we structurally separated the Hsp90 membrane-deforming function from its well-characterized chaperone activity"
  - statement: Open Hsp90 dimer exposes helix for MVB fusion
    supporting_text: "mutations and drugs that stabilize the open Hsp90 dimer expose the helix and allow MVB fusion"
- id: PMID:30245208
  title: Hsp83/Hsp90 Physically Associates with Insulin Receptor to Promote Neural Stem
    Cell Reactivation.
  findings:
  - statement: Hsp83 is both necessary and sufficient for NSC reactivation by promoting activation of InR pathway
    supporting_text: "Hsp83 is both necessary and sufficient for NSC reactivation by promoting the activation of InR pathway in larval brains in the presence of dietary amino acids"
  - statement: Both Hsp83 and its co-chaperone Cdc37 physically associate with InR
    supporting_text: "Both Hsp83 and its co-chaperone Cdc37 physically associate with InR"
- id: PMID:31907206
  title: Drosophila Morgana is an Hsp90-interacting protein with a direct role in
    microtubule polymerisation.
  findings:
  - statement: Morgana co-purifies with Hsp90-R2TP-TTT supercomplex
    supporting_text: "Mora localises to mitotic spindles and co-purifies with the Hsp90-R2TP-TTT supercomplex and with additional well-known Hsp90 co-chaperones"
  - statement: Mora localises to mitotic spindles
    supporting_text: "Drosophila Mora localises to mitotic spindles and co-purifies with the Hsp90-R2TP-TTT supercomplex"
- id: PMID:33176138
  title: Modulation of Ago2 Loading by Cyclophilin 40 Endows a Unique Repertoire of
    Functional miRNAs during Sperm Maturation in Drosophila.
  findings:
  - statement: Cyp40 interacts with duplex-incorporating Ago2 through Hsp90 in vitro
    supporting_text: "Cyp40 interacts with duplex-incorporating Ago2 through Hsp90 in vitro and selectively promotes the build-up of Ago2-bound miRNAs"
  - statement: Identifies RISC-regulatory roles for Hsp90 machinery
    supporting_text: "these results identify RISC-regulatory roles for Hsp90 machinery"
- id: PMID:21186352
  title: Drosophila Piwi functions in Hsp90-mediated suppression of phenotypic variation.
  findings:
  - statement: Hsp83 interacts with Hop and Piwi
    supporting_text: "we isolated a protein complex composed of Hsp90, Piwi and Hop, the Hsp70/Hsp90 organizing protein homolog"
  - statement: Required for piRNA biogenesis and transposon suppression
    supporting_text: "Hsp90 and Hop regulate the piRNA pathway through Piwi to mediate canalization"
  - statement: Mediates developmental robustness via epigenetic silencing
    supporting_text: "epigenetic silencing of the expression of existing genetic variants and the suppression of transposon-induced new genetic variation as two major mechanisms underlying piRNA pathway-mediated canalization"
- id: file:DROME/Hsp83/Hsp83-deep-research-falcon.md
  title: Falcon deep research report on Hsp83 (Drosophila melanogaster)
  findings:
  - statement: |-
      Hsp83 is the cytosolic Hsp90 ATP-dependent chaperone that operates via an
      ATP-driven conformational cycle to promote late-stage folding, maturation,
      stabilization, and activation of diverse signaling/developmental client proteins.
    supporting_text: |-
      Hsp83 is best understood as the **cytosolic Hsp90 ATP-dependent chaperone** that promotes **late-stage folding/maturation, stabilization, and activation** of diverse client proteins, especially those central to signaling and development (prodromou2022advancestowardsunderstanding pages 1-3, oostenhawle2023organismalrolesof pages 1-3). Mechanistically, Hsp90 proteins are **dimeric**, undergoing an **ATP-driven conformational cycle** involving **ATP binding/hydrolysis** and large structural rearrangements that enable remodeling/maturation of clients
    reference_section_type: OTHER
  - statement: |-
      The Hsp83/Hsp90 chaperone cycle is regulated by co-chaperones including Cdc37
      (kinase client recruitment), p23, Aha1, and TPR-domain proteins such as Hop
      that bind the conserved C-terminal MEEVD motif of cytosolic Hsp90.
    supporting_text: |-
      Key named regulators include **Cdc37** (kinase client recruitment), **p23**, and **Aha1**, as well as **TPR-domain** proteins such as **Hop** that bind the conserved **MEEVD** C-terminal motif typical of cytosolic Hsp90s
    reference_section_type: OTHER
  - statement: |-
      Hsp83/Hsp90 is required to activate the ecdysone receptor heterodimer EcR/USP;
      a purified Hsp83-Hsc70-Hop-Hip-FKBP52-p23 multichaperone complex reconstitutes
      functional EcR/USP DNA binding in vitro, and activation requires ATP hydrolysis
      and Mg2+. This is a steroid-hormone-receptor maturation role analogous to
      mammalian Hsp90 chaperoning of nuclear receptors.
    supporting_text: |-
      A key Drosophila primary study demonstrated that the **ecdysone receptor heterodimer EcR/USP requires an Hsp83/Hsp90-containing multichaperone complex for activation**. Purified components—Hsp83 (Hsp90), Hsc70, Hop, Hip, FKBP52, and p23—were sufficient to reconstitute functional EcR/USP DNA binding in vitro, and activation required **ATP hydrolysis and Mg2+**
    reference_section_type: OTHER
  - statement: |-
      Hsp83 facilitates juvenile hormone signaling by promoting nuclear import of the
      JH receptor Methoprene-tolerant (Met). Hsp83 physically interacts with Met, JH
      enhances this interaction, and Hsp83 loss of function reduces JH-induced Met
      nuclear import and JH-responsive Kr-h1 transcription.
    supporting_text: |-
      In Drosophila juvenile hormone signaling, Hsp83 physically interacts with the JH receptor **Methoprene-tolerant (Met)**, and JH increases the Met–Hsp83 interaction. Hsp83 loss-of-function attenuates JH binding and reduces JH-induced **nuclear import** of Met, decreasing JH-responsive transcription of **Kr-h1**
    reference_section_type: OTHER
  - statement: |-
      Hsp83 promotes timely terminal cell cycle exit during pupal development. Partial
      loss of function increases E2F-dependent transcription and causes ectopic S phase
      and mitosis after neighboring wild-type cells have become postmitotic, consistent
      with chaperoning of cell-cycle/APC-C regulators.
    supporting_text: |-
      In Hsp83(6-55) mutant clones, E2F-dependent transcription increases and cells show ectopic S phase and mitosis after neighboring cells have exited the cell cycle
    reference_section_type: OTHER
  - statement: |-
      Hsp83 is essential and required throughout spermatogenesis, particularly for
      microtubule-dependent steps; biochemical data indicate an indirect role via
      stabilization/maturation of microtubule effectors and signaling components
      rather than direct tubulin polymerization.
    supporting_text: |-
      Phenotypically, **all stages of spermatogenesis involving microtubule function are affected**, from early mitotic divisions through sperm maturation and individualization/motility (yue1999geneticanalysisof pages 1-2). In a viable male-sterile allele (*scratch*), Hsp83/Hsp90 protein was reduced by **~3-fold** (ovaries, testes, male bodies), correlating with fully penetrant male sterility (yue1999geneticanalysisof pages 5-7). Biochemically, only a small fraction of Hsp83 co-purifies with taxol-stabilized microtubule proteins, and Hsp83 does not remain bound through repeated microtubule assembly/disassembly, supporting an **indirect role** via stabilization/maturation of microtubule effectors and/or signaling components rather than direct tubulin polymerization
    reference_section_type: OTHER
  - statement: |-
      Hsp83 contributes to female fertility and oogenesis, interacting with the
      translational regulator Cup and affecting maternal mRNA handling, including
      nanos mRNA localization relevant to anterior-posterior embryonic patterning.
    supporting_text: |-
      Hsp83 also contributes to female fertility, oogenesis, and maternal RNA regulation. It interacts with the translational regulator Cup during oogenesis, localizes maternal transcripts, and affects *nanos* mRNA localization, linking Hsp83 to anterior–posterior patterning in embryos.
    reference_section_type: OTHER
  - statement: |-
      Hsp83/Hsp90 buffers cryptic genetic variation and supports fitness in natural
      fly populations; reduced expression lowers fecundity and longevity and weakens
      robustness, especially under inbreeding and mild heat stress, supporting the
      classic capacitor (canalization) model in a population context.
    supporting_text: |-
      Hsp83/Hsp90 buffers cryptic genetic variation and supports fitness in natural fly populations. Reduced Hsp83 expression from naturally occurring insertions lowers fecundity and longevity and weakens robustness, especially under inbreeding and mild heat stress, supporting the classic
    reference_section_type: OTHER
  - statement: |-
      Hsp83 can act as a constitutive proteostasis factor whose transcription is not
      necessarily induced in all proteotoxic stress states; in a 2023 larval fat body
      study Hsp83 (and Gp93) did not change despite induction of Hsp70/Hsp40-class
      stress genes, qualifying the strength of an inducible heat-response annotation.
    supporting_text: |-
      A 2023 Nature Communications study in Drosophila larval fat body found that **Nacα reduction activates a heat shock response**, with upregulation of Hsp70/Hsp40 class genes and oxidative stress markers, but **Hsp83 (and another Hsp90-family gene Gp93) did not change** in that context (qRT-PCR, n=4 batches)
    reference_section_type: OTHER
core_functions:
- description: The primary molecular function of Hsp83. As a member of the HSP90 family,
    Hsp83 binds near-native client proteins and uses its intrinsic ATPase activity
    to drive conformational changes that promote client maturation, activation, and
    stabilization. Known clients include kinases (insulin receptor, LKB1), transcription
    factors, Argonaute, APC/C components (Cdh1/Fzr), and centrosomal proteins.
  molecular_function:
    id: GO:0140662
    label: ATP-dependent protein folding chaperone
  directly_involved_in:
  - id: GO:0006457
    label: protein folding
  - id: GO:0050821
    label: protein stabilization
  - id: GO:0034605
    label: cellular response to heat
  - id: GO:0070922
    label: RISC complex assembly
  locations:
  - id: GO:0005829
    label: cytosol
  in_complex:
    id: GO:0101031
    label: protein folding chaperone complex
  supported_by:
  - reference_id: PMID:29775584
    supporting_text: the Hsp90 system is required to extend the dwell time of Ago2
      in the open state
  - reference_id: PMID:23509070
    supporting_text: Sicily preprotein interacts with cytosolic Hsp90 to chaperone
      the CI subunit, ND42, before mitochondrial import

Hsp83

Gene Description

Existing Annotations Review

Core Functions

References

Deep Research

Falcon

Research report: Functional annotation of Hsp83 (UniProt P02828) in Drosophila melanogaster

0) Target verification (mandatory disambiguation)

1) Key concepts and definitions (current understanding)

1.1 Core molecular function

1.2 Chaperone cycle partners (co-chaperones)

2) Drosophila-specific functional annotation (processes, pathways, localization)

2.1 Subcellular localization

2.2 Essentiality and organismal roles in development

2.3 Spermatogenesis: requirement for microtubule-dependent processes

2.4 Oogenesis, maternal contribution, and embryonic patterning

2.5 Hormone signaling pathway 1: Ecdysone receptor activation (steroid receptor biology)

2.6 Hormone signaling pathway 2: Juvenile hormone (JH) receptor Met nuclear import

2.7 Cell cycle exit and developmental proliferation control

3) Recent developments and latest research (prioritizing 2023–2024)

3.1 2023: organismal and inter-tissue roles of Hsp90

3.2 2023: tissue proteostasis response where Hsp83 is not induced

3.3 2024: structural proteomics and orthology context (supporting identity)

4) Current applications and real-world implementations

5) Expert opinions and analysis (authoritative synthesis)

6) Statistics and data highlights (recent and foundational)

Evidence summary table

Visual evidence (selected)

Practical functional annotation statement (concise)

Artifacts

Citations

📚 Additional Documentation

Bioreason Rl Predictions

BioReason Chat Export

Thinking Trace

Functional Summary

UniProt Summary

InterPro Domains

GO Terms

Bioreason Rl Review

BioReason-Pro RL Review: Hsp83 (DROME)

Functional Summary Review

Notes on thinking trace

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