SSA2

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0005634 nucleus	IBA GO_REF:0000033	KEEP AS NON CORE	Summary: SSA2 nuclear localization is supported by NAS evidence from PMID:15102838 (HAP1 repressor complex). As a close paralog of SSA1 (97% identity), SSA2 is expected to share nuclear localization. SSA1 has direct IDA evidence for nuclear localization (PMID:10347213). Reason: Correct and consistent with the HAP1 complex, but nuclear localization is secondary to Ssa2's predominant cytosolic chaperone function.
GO:0005737 cytoplasm	IBA GO_REF:0000033	ACCEPT	Summary: SSA2 is a major cytoplasmic Hsp70. IBA is consistent with IDA evidence from PMID:8755907 and UniProt subcellular location annotation. Reason: Core localization. SSA2 is constitutively expressed and highly abundant in the cytoplasm.
GO:0005886 plasma membrane	IBA GO_REF:0000033	REMOVE	Summary: The pinned GOA row carries a plasma-membrane IBA, but the current local PTHR19375 PAINT snapshot no longer places GO:0005886 at the cited PTN002500132 node. This stale propagation is removed independently of the separate experimental HDA row, which is retained conservatively as non-core. Reason: The pinned 2025 GOA row points to PAINT node PTN002500132, whereas the current PTHR19375 snapshot has nucleus and cytosol IBD rows at that node and no plasma-membrane IBD row. The source state is therefore stale or missing; this conclusion is based on current node content, not donor count. Propagation Review Root cause: SOURCE STALE OR MISSING Sources checked: PANTHER:PTN002500132 · PAINT Hsp70 family node SOURCE STALE OR MISSING Current PTHR19375 data retain GO:0005634 and GO:0005829 at this node but not GO:0005886.
GO:0016887 ATP hydrolysis activity	IBA GO_REF:0000033	ACCEPT	Summary: SSA2 has ATPase activity supported by ISS evidence from PMID:8151709. As a 97% identical paralog of SSA1, which has well-characterized ATPase activity (PMID:7737974), SSA2's ATPase activity is certain. Reason: Core molecular function. The ATPase activity drives the chaperone cycle. SSA2 is 97% identical to SSA1 whose ATPase activity is biochemically established. Supporting Evidence: file:yeast/SSA2/SSA2-deep-research-falcon.md The N-terminal nucleotide-binding domain (NBD) is implicated in ATPase-cycle control (Ydj1 binds the NBD to stimulate ATPase activity).
GO:0031072 heat shock protein binding	IBA GO_REF:0000033	ACCEPT	Summary: SSA2 interacts with numerous heat shock proteins including HSP82, HSC82, SSE1, SIS1, STI1, SBA1, and HSP26/HSP42. UniProt lists extensive IntAct interaction data. Reason: The current PAINT assertion is supported at Hsp70 family node PTN000452648. Targeted Hsp70-Hsp90 network evidence corroborates the interaction class; bulk interaction screens provide context but are not used alone to infer this molecular function. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000452648 · PAINT Hsp70 family node SUPPORTS TRANSFER The current PTHR19375 snapshot carries GO:0031072 as an IBD assertion at PTN000452648 and supports transfer to Ssa2. Supporting Evidence: file:yeast/SSA2/SSA2-deep-research-falcon.md Hsp90 (Hsp82): receives certain clients after Hsp70 processing; Ssa2 participates in upstream client handling and transfer toward Hsp90. file:yeast/SSA2/SSA2-deep-research-falcon.md Hsp40/J-domain cochaperone Ydj1: recruits misfolded clients to Hsp70 and stimulates Hsp70 ATPase activity and substrate transfer.
GO:0044183 protein folding chaperone	IBA GO_REF:0000033	MODIFY	Summary: SSA2 is a bona fide protein folding chaperone. PMID:8947547 demonstrated that immunodepletion of Ssa1/2p from yeast cytosol dramatically reduced refolding of denatured luciferase. PMID:9789005 showed SSA-dependent folding of newly translated OTC in vivo. Reason: The family-level chaperone term is correct but less precise than the experimentally supported ATP-dependent Hsp70 mechanism. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Sources checked: PANTHER:PTN000452648 · PAINT Hsp70 family node SUPPORTS TRANSFER The family transfer correctly identifies chaperone activity in Ssa2, but GO:0140662 captures its ATP-dependent mechanism more precisely. Proposed replacements: ATP-dependent protein folding chaperone Supporting Evidence: PMID:8947547 Depletion of Ssa1/2p had no effect on the ability of the yeast lysate to synthesize enzymatically active luciferase, but had a dramatic effect on the ability of the lysate to refold chemically denatured luciferase. file:yeast/SSA2/SSA2-deep-research-falcon.md SSA2 encodes an ATP-dependent molecular chaperone of the Hsp70 family. Rather than catalyzing a metabolic reaction with a defined substrate/product, Ssa2 performs ATP-driven cycles of client binding and release to prevent aggregation and promote folding/refolding and quality control.
GO:0005829 cytosol	IBA GO_REF:0000033	ACCEPT	Summary: SSA2 is primarily a cytosolic protein. IBA is consistent with IDA evidence from PMID:16806052. Reason: Core localization. SSA2 is the major cytosolic Hsp70 along with SSA1. Supporting Evidence: file:yeast/SSA2/SSA2-deep-research-falcon.md Fluorescence microscopy of N-terminally tagged Ssa proteins (including Ssa2) shows predominantly diffuse signal in most cells, supporting predominant cytosolic localization under those conditions. file:yeast/SSA2/SSA2-deep-research-falcon.md Gaur et al. explicitly treat Ssa2 as one of four cytosolic Ssa Hsp70s acting in the Hsp90 pathway.
GO:0042026 protein refolding	IBA GO_REF:0000033	ACCEPT	Summary: SSA2 is directly involved in protein refolding. PMID:8947547 demonstrated that Ssa1/2p depletion dramatically reduced refolding capacity of yeast cytosol. Reason: Well-supported core function. Refolding of denatured proteins is a central activity of SSA2 as demonstrated by PMID:8947547. Supporting Evidence: PMID:8947547 These results demonstrate, for the first time, the refolding activity of Ssa1/2p in the context of the yeast cytosol, and define refolding activity as a chaperone function specific to Ssa1/2p file:yeast/SSA2/SSA2-deep-research-falcon.md Ydj1-assisted luciferase refolding activity was reported as ~25–30-fold higher with Ssa2 than with Ssa4, consistent with stronger Ydj1–Ssa2 functional coupling.
GO:0000049 tRNA binding	IEA GO_REF:0000117	KEEP AS NON CORE	Summary: IEA annotation for tRNA binding. Consistent with IDA evidence from PMID:25853343 which demonstrated that SSA2 directly binds tRNA as part of a tRNA nuclear import system. Reason: Correct but non-core. Supported by direct experimental evidence (IDA from PMID:25853343). tRNA binding is a specialized moonlighting activity of SSA2.
GO:0000166 nucleotide binding	IEA GO_REF:0000043	MARK AS OVER ANNOTATED	Summary: SSA2 binds ATP and ADP as part of its chaperone cycle. This is a parent term of ATP binding and is correct but overly general. Reason: The annotation is not false, but it is redundant and substantially less informative than the existing ATP-binding and ATP-hydrolysis annotations.
GO:0000329 fungal-type vacuole membrane	IEA GO_REF:0000117	KEEP AS NON CORE	Summary: SSA2 localization to the vacuole membrane is supported by IDA evidence from PMID:10745074, which showed cytosolic Hsp70 involvement in aminopeptidase I transport to the vacuole. Reason: Direct experiments support Ssa1/2 localization at the vacuolar membrane during Ape1 transport, but this is a specialized localization rather than the core site of Ssa2 chaperone activity.
GO:0005524 ATP binding	IEA GO_REF:0000120	ACCEPT	Summary: SSA2 binds ATP through its nucleotide-binding domain. This is core to its function. Also supported by IDA from PMID:10893257. Reason: Correct and fundamental. ATP binding is essential for the SSA2 chaperone cycle. Supporting Evidence: file:yeast/SSA2/SSA2-deep-research-falcon.md This is evidenced in (i) biochemical handling consistent with ATP-binding Hsp70 behavior (purification via ATP-agarose and ATP elution) and (ii) mechanistic descriptions of cochaperone control of the Hsp70 ATPase cycle (Ydj1 stimulating ATPase activity and substrate transfer).
GO:0005737 cytoplasm	IEA GO_REF:0000044	ACCEPT	Summary: Duplicate of the IBA and IDA annotations for cytoplasm. Correct. Reason: Correct. Redundant with IBA and IDA annotations but acceptable.
GO:0006457 protein folding	IEA GO_REF:0000117	ACCEPT	Summary: SSA2 is directly involved in protein folding as demonstrated experimentally (IDA from PMID:7867784, IMP from PMID:9448096). IEA is consistent. Reason: Correct. Consistent with direct experimental evidence.
GO:0006616 SRP-dependent cotranslational protein targeting to membrane, translocation	IEA GO_REF:0000117	MODIFY	Summary: SSA2 has been implicated in protein translocation to the ER membrane (IMP from PMID:8754838). However, PMID:8947547 found that depletion of Ssa1/2p had no effect on translocation efficiency in vitro. The role may be more indirect. Reason: The SSA/Ydj1 evidence concerns post-translational precursor translocation, not the SRP-dependent cotranslational route. The replacement captures the supported class-level mechanism without making it core. Proposed replacements: post-translational protein targeting to membrane, translocation Supporting Evidence: PMID:8754838 Of six proteins destined for the endoplasmic reticulum, the translocation of only prepro-alpha-factor and proteinase A was inhibited. PMID:8947547 Depletion of Ssa1/2p had no effect on the efficiency of translocation in this in vitro assay.
GO:0009277 fungal-type cell wall	IEA GO_REF:0000117	KEEP AS NON CORE	Summary: SSA2 has been detected in the cell wall by IDA (PMID:8755907). IEA is consistent. UniProt also annotates SSA2 to the cell wall. Reason: Direct surface-localization experiments support the cell-wall annotation, but it is secondary to the core cytosolic chaperone function.
GO:0016887 ATP hydrolysis activity	IEA GO_REF:0000002	ACCEPT	Summary: Duplicate of IBA and ISS annotations. Correct InterPro-based annotation. Reason: Correct. Redundant with IBA and ISS annotations but acceptable.
GO:0033554 cellular response to stress	IEA GO_REF:0000117	KEEP AS NON CORE	Summary: SSA2 is a heat shock protein involved in stress response. Although SSA2 is constitutively expressed (unlike the stress-induced SSA3/SSA4), it participates in protein quality control during stress. Reason: Correct but broad and secondary to Ssa2's direct folding/refolding mechanism. Supporting Evidence: file:yeast/SSA2/SSA2-deep-research-falcon.md Disrupting the Hsf1-binding site in SSA2 (ssa2ΔHSE) was associated with elevated basal HSE-YFP reporter and reduced induction after prolonged heat shock, and the authors interpret the reduced induction as explained by the increased basal reporter level—consistent with SSA2 contributing to basal repression/feedback behavior in the Hsf1 regulon context.
GO:0043161 proteasome-mediated ubiquitin-dependent protein catabolic process	IEA GO_REF:0000117	KEEP AS NON CORE	Summary: SSA2 participates in ubiquitin-dependent protein degradation. Consistent with IGI evidence from PMID:27178214. Reason: Correct but non-core. SSA2 assists in presenting misfolded substrates to the ubiquitin-proteasome system as part of its broader protein quality control role. Supporting Evidence: file:yeast/SSA2/SSA2-deep-research-falcon.md SSA2 is an ATP-dependent molecular chaperone of the Hsp70 family that binds ATP and acts with Hsp40 cochaperones and nucleotide exchange factors to prevent aggregation, assist folding/refolding, and support degradation/translocation of client proteins.
GO:0051082 unfolded protein binding	IEA GO_REF:0000117	MODIFY	Summary: GO:0051082 (unfolded protein binding) is now formally obsolete. SSA2 does bind unfolded proteins, but this is part of its chaperone activity, not a standalone binding function. The appropriate replacement is GO:0140662 (ATP-dependent protein folding chaperone). Reason: GO:0051082 is now formally obsolete. SSA2 binds unfolded proteins as part of its ATP-dependent chaperone cycle. The correct annotation is GO:0140662 (ATP-dependent protein folding chaperone) or the already-present GO:0044183 (protein folding chaperone). Proposed replacements: ATP-dependent protein folding chaperone
GO:0051170 import into nucleus	IEA GO_REF:0000117	KEEP AS NON CORE	Summary: SSA2 is involved in tRNA import into the nucleus (IMP from PMID:25853343, PMID:33074312). This IEA is a broader parent term consistent with the experimental evidence. Reason: Correct but broad and secondary. It is supported through Ssa2's specialized tRNA-import role rather than its core ATP-dependent folding/refolding mechanism.
GO:0005515 protein binding	IPI PMID:14729968 The ctf13-30/CTF13 genomic haploinsufficiency modifier scree...	MARK AS OVER ANNOTATED	Summary: IPI evidence from ctf13-30/CTF13 haploinsufficiency screen. SSA2 is a chaperone that binds many client proteins. Reason: The interaction may be real, but generic protein binding is uninformative and the haploinsufficiency interaction does not by itself establish chaperone activity.
GO:0005515 protein binding	IPI PMID:15766533 Navigating the chaperone network: an integrative map of phys...	MODIFY	Summary: IPI evidence for SSA2 binding HSP82 and HSC82 from chaperone network mapping. These are well-known Hsp70-Hsp90 interactions. Reason: Protein binding is uninformative. The Hsp70-Hsp90 interaction is better captured by GO:0031072 (heat shock protein binding) which is already annotated via IBA. Proposed replacements: heat shock protein binding
GO:0005515 protein binding	IPI PMID:16284124 An integrated mass spectrometry-based proteomic approach: qu...	MARK AS OVER ANNOTATED	Summary: IPI evidence for SSA2 binding proteasome subunits from a proteasome interactome study. Reason: The interaction may be real, but generic protein binding is uninformative and a proteasome interaction does not by itself establish chaperone activity.
GO:0005515 protein binding	IPI PMID:16429126 Proteome survey reveals modularity of the yeast cell machine...	MARK AS OVER ANNOTATED	Summary: Large-scale proteome survey (Gavin et al. 2006) identifying many SSA2 interaction partners by TAP-MS. Reason: Generic protein binding is uninformative, and large-scale interaction evidence alone cannot distinguish a chaperone substrate from another interactor.
GO:0005515 protein binding	IPI PMID:16606443 Comparative analysis of Saccharomyces cerevisiae WW domains ...	MARK AS OVER ANNOTATED	Summary: IPI evidence from analysis of WW domain-containing proteins and their interacting partners. Reason: Generic protein binding is uninformative, and this interaction study does not establish a more specific molecular function for Ssa2.
GO:0005515 protein binding	IPI PMID:17441508 SGT2 and MDY2 interact with molecular chaperone YDJ1 in Sacc...	MARK AS OVER ANNOTATED	Summary: IPI evidence for SSA2 binding SGT2 via Ydj1 co-chaperone. Reason: The interaction may be biologically relevant to the chaperone network, but generic protein binding is uninformative and does not itself establish an activity term.
GO:0005515 protein binding	IPI PMID:17892321 Structure-templated predictions of novel protein interaction...	MARK AS OVER ANNOTATED	Summary: Structure-templated predictions of protein interactions. Reason: Generic protein binding is uninformative, and a structure-templated interaction prediction cannot establish Ssa2 chaperone activity.
GO:0005515 protein binding	IPI PMID:19536198 An atlas of chaperone-protein interactions in Saccharomyces ...	MARK AS OVER ANNOTATED	Summary: Atlas of chaperone-protein interactions (Gong et al. 2009). Systematic mapping of SSA2 chaperone-client interactions. Reason: The mapped interactions are compatible with chaperone-client relationships, but generic protein binding is uninformative and cannot encode chaperone activity.
GO:0005515 protein binding	IPI PMID:37070168 RNA-dependent interactome allows network-based assignment of...	MARK AS OVER ANNOTATED	Summary: RNA-dependent interactome study. Reason: Generic protein binding is uninformative, and an RNA-dependent interactome result does not by itself establish a more specific molecular function.
GO:0005515 protein binding	IPI PMID:37968396 The social and structural architecture of the yeast protein ...	MARK AS OVER ANNOTATED	Summary: Social and structural architecture of yeast protein interactome. Large-scale study. Reason: Generic protein binding is uninformative, and a large-scale interactome edge does not by itself establish Ssa2 chaperone activity.
GO:0005515 protein binding	IPI PMID:9819422 Cns1 is an essential protein associated with the hsp90 chape...	MODIFY	Summary: IPI evidence for SSA2 binding HSP82 and CPR7 via Cns1. Reason: Protein binding is uninformative. The Ssa2-Hsp82/Cpr7 interaction is a chaperone network interaction better captured by GO:0031072. Proposed replacements: heat shock protein binding
GO:0005634 nucleus	NAS PMID:15102838 A novel mode of chaperone action: heme activation of Hap1 by...	KEEP AS NON CORE	Summary: NAS annotation from ComplexPortal for SSA2 nuclear localization in context of the HAP1 repressor complex (CPX-1883). Consistent with IBA. Reason: Correct, but this nuclear client-specific role is secondary to Ssa2's core cytosolic chaperone function.
GO:0045892 negative regulation of DNA-templated transcription	NAS PMID:15102838 A novel mode of chaperone action: heme activation of Hap1 by...	KEEP AS NON CORE	Summary: SSA2 is part of the HAP1 transcriptional repressor complex (ComplexPortal CPX-1883) where it represses HAP1-dependent transcription in the absence of heme. Reason: Genuine but secondary function. SSA2 acts as a repressive chaperone holdase for HAP1, preventing transcriptional activation. This is not a core molecular function but rather a consequence of its chaperone activity on a specific client.
GO:0070482 response to oxygen levels	NAS PMID:15102838 A novel mode of chaperone action: heme activation of Hap1 by...	KEEP AS NON CORE	Summary: SSA2 is part of the HAP1 complex that responds to heme/oxygen levels. Reason: Secondary consequence of SSA2's role in the HAP1 repressor complex, not a core function.
GO:0070482 response to oxygen levels	NAS PMID:9632766 Molecular mechanism governing heme signaling in yeast: a hig...	KEEP AS NON CORE	Summary: Same process annotation from a different reference. PMID:9632766 describes the higher-order HAP1 complex mechanism. Reason: Duplicate process annotation for the same indirect role. SSA2 participates in oxygen/heme signaling through the HAP1 complex but this is not its core function.
GO:1903561 extracellular vesicle	IDA PMID:38711329 Thermotolerance in S. cerevisiae as a model to study extrace...	KEEP AS NON CORE	Summary: PMID:38711329 detected SSA2 in extracellular vesicles during thermotolerance studies. Reason: Genuine but peripheral localization. SSA2 in extracellular vesicles likely reflects its abundance rather than a specific targeting function.
GO:0009267 cellular response to starvation	IMP PMID:25853343 Cytosolic Hsp70 and co-chaperones constitute a novel system ...	KEEP AS NON CORE	Summary: PMID:25853343 showed SSA2 involvement in tRNA nuclear import which is regulated by nutrient status/starvation. Reason: Genuine but secondary function. The starvation response of SSA2 is related to its role in tRNA import regulation.
GO:0035719 tRNA import into nucleus	IMP PMID:33074312 A novel assay provides insight into tRNAPhe retrograde nucle...	KEEP AS NON CORE	Summary: PMID:33074312 demonstrated SSA2's role in tRNA nuclear import via mutant phenotype analysis. Reason: Genuine but specialized function. tRNA nuclear import is a moonlighting activity of SSA2 distinct from its core chaperone function.
GO:0005739 mitochondrion	HDA PMID:24769239 Quantitative variations of the mitochondrial proteome and ph...	KEEP AS NON CORE	Summary: HDA evidence from mitochondrial proteome/phosphoproteome study. SSA2 was detected in mitochondrial fractions. Reason: Retain as a non-core high-throughput mitochondrial-fraction association; Ssa2 is predominantly cytosolic and can act peripherally at organelles.
GO:0005886 plasma membrane	HDA PMID:16622836 The plasma membrane proteome of Saccharomyces cerevisiae and...	KEEP AS NON CORE	Summary: HDA evidence from plasma membrane proteome study. SSA2 was detected in the plasma membrane fraction. Reason: Retain conservatively as a non-core high-throughput fractionation result; the abstract does not establish a stable or functional plasma-membrane pool.
GO:0043161 proteasome-mediated ubiquitin-dependent protein catabolic process	IGI PMID:27178214 The requirements of yeast Hsp70 of SSA family for the ubiqui...	KEEP AS NON CORE	Summary: PMID:27178214 demonstrated SSA family requirement for ubiquitin-dependent degradation of short-lived and abnormal proteins via genetic interaction. Reason: Genuine but secondary function. SSA2 assists in presenting misfolded substrates to the ubiquitin-proteasome system as part of its broader protein quality control role.
GO:0000049 tRNA binding	IDA PMID:25853343 Cytosolic Hsp70 and co-chaperones constitute a novel system ...	KEEP AS NON CORE	Summary: PMID:25853343 demonstrated that cytosolic Hsp70 (SSA2) directly binds tRNA as part of a tRNA nuclear import system. Reason: Genuine but specialized function. tRNA binding is a moonlighting activity of SSA2 related to its role in tRNA nuclear import.
GO:0035719 tRNA import into nucleus	IMP PMID:25853343 Cytosolic Hsp70 and co-chaperones constitute a novel system ...	KEEP AS NON CORE	Summary: PMID:25853343 demonstrated SSA2's role in tRNA import into the nucleus. Reason: Genuine but specialized function. Same as the other tRNA import annotation, from a different PMID.
GO:0016887 ATP hydrolysis activity	ISS PMID:8151709 Molecular evolution of the HSP70 multigene family.	ACCEPT	Summary: ISS annotation based on molecular evolution of the HSP70 multigene family. Consistent with SSA2's function as an ATPase. Reason: Correct. SSA2 has ATPase activity essential for its chaperone cycle. Redundant with IBA but acceptable.
GO:0051082 unfolded protein binding	ISS PMID:8151709 Molecular evolution of the HSP70 multigene family.	MODIFY	Summary: GO:0051082 is now formally obsolete. SSA2 binds unfolded proteins as part of its ATP-dependent chaperone cycle, not as a standalone binding activity. Reason: GO:0051082 is now formally obsolete. The correct replacement is GO:0140662 (ATP-dependent protein folding chaperone). SSA2 binds unfolded proteins as part of its chaperone function. Proposed replacements: ATP-dependent protein folding chaperone
GO:0000329 fungal-type vacuole membrane	IDA PMID:10745074 Cytosolic Hsp70s are involved in the transport of aminopepti...	KEEP AS NON CORE	Summary: PMID:10745074 showed cytosolic Hsp70s are involved in transport of aminopeptidase I from cytoplasm into the vacuole, and SSA2 localizes to the vacuole membrane. Reason: Direct experiments support transient vacuolar-membrane localization in Ape1 transport, but this is a specialized application of Ssa2 function.
GO:0005524 ATP binding	IDA PMID:10893257 The heat shock protein Ssa2p is required for import of fruct...	ACCEPT	Summary: PMID:10893257 demonstrated that SSA2 binds ATP, and this binding is required for import of fructose-1,6-bisphosphatase into Vid vesicles. Reason: Core molecular function with direct experimental evidence. Supporting Evidence: PMID:10893257 The heat shock protein Ssa2p was identified as one of the ATP binding proteins involved in FBPase import.
GO:0005737 cytoplasm	IDA PMID:8755907 Members of the Hsp70 family of proteins in the cell wall of ...	ACCEPT	Summary: PMID:8755907 identified Hsp70 family members including SSA2 in the cell wall and confirmed cytoplasmic localization. Reason: Correct core localization with direct experimental evidence.
GO:0005739 mitochondrion	IDA PMID:16806052 MMI1 (YKL056c, TMA19), the yeast orthologue of the translati...	KEEP AS NON CORE	Summary: PMID:16806052 detected SSA2 in mitochondrial fractions. SSA2 likely associates with mitochondria in the context of protein import. Reason: The mitochondrial-fraction association is retained, but it is secondary to Ssa2's predominant cytosolic localization and likely reflects a peripheral protein-targeting role.
GO:0005829 cytosol	IDA PMID:16806052 MMI1 (YKL056c, TMA19), the yeast orthologue of the translati...	ACCEPT	Summary: PMID:16806052 confirmed SSA2 cytosolic localization. Reason: Correct core localization. SSA2 is predominantly cytosolic.
GO:0006457 protein folding	IDA PMID:7867784 Cooperation of the molecular chaperone Ydj1 with specific Hs...	ACCEPT	Summary: Direct assay demonstrating SSA2 involvement in protein folding. Reason: Core biological process. Direct experimental demonstration of SSA2's role in protein folding. Supporting Evidence: file:yeast/SSA2/SSA2-deep-research-falcon.md Using v-Src as an Hsp90 client, Gaur et al. show that the Hsp40 cochaperone Ydj1 binds misfolded client, recruits it to Hsp70, and transfers it preferentially to Ssa2 (relative to Ssa4). Transfer to Ssa2 supports subsequent engagement with Hsp90 and client maturation.
GO:0006457 protein folding	IMP PMID:9448096 Role of Hsp70 subfamily, Ssa, in protein folding in yeast ce...	ACCEPT	Summary: PMID:9448096 showed that ssa1ssa2 mutants had significantly lower luciferase activity than wild type, demonstrating SSA proteins are needed for folding of proteins. The reduced folding capacity in ssa1ssa2 cells closely correlated with the amount of Ssa proteins present. Reason: Core biological process. Mutant phenotype demonstrates SSA2 (with SSA1) is required for protein folding in vivo. Supporting Evidence: PMID:9448096 The luciferase activity was significantly lower in ssa1ssa2 transformants than in the wild type (wt) cell transformed with the same plasmid PMID:9448096 It is suggested that constitutional Ssa "chaperones" are needed for the folding of proteins and, in cells lacking Ssa1 and Ssa2, the increased Ssa4 is thought to partly compensate for their role in the folding of luciferase in vivo
GO:0006616 SRP-dependent cotranslational protein targeting to membrane, translocation	IMP PMID:8754838 Functional interaction of cytosolic hsp70 and a DnaJ-related...	MODIFY	Summary: PMID:8754838 showed that SSA-deficient mutants (ssa1ts ssa2 ssa3 ssa4) had translocation defects for prepro-alpha-factor and proteinase A. However, PMID:8947547 later showed depletion of Ssa1/2p had no effect on translocation efficiency in vitro. Reason: PMID:8754838 supports an in-vivo SSA/Ydj1 role in post-translational precursor import, not SRP-dependent cotranslational targeting. PMID:8947547 further shows that Ssa1/2 depletion did not reduce translocation in its cell-free assay, so this remains a non-core class-level role. Proposed replacements: post-translational protein targeting to membrane, translocation Supporting Evidence: PMID:8754838 Of six proteins destined for the endoplasmic reticulum, the translocation of only prepro-alpha-factor and proteinase A was inhibited. PMID:8947547 Depletion of Ssa1/2p had no effect on the efficiency of translocation in this in vitro assay.
GO:0009277 fungal-type cell wall	IDA PMID:8755907 Members of the Hsp70 family of proteins in the cell wall of ...	KEEP AS NON CORE	Summary: PMID:8755907 directly identified SSA2 as a cell wall protein. UniProt also annotates SSA2 subcellular location as "Secreted, cell wall." Reason: Direct surface-localization experiments support cell-wall exposure, but this is not the core site of Ssa2 chaperone activity.
GO:0051082 unfolded protein binding	IGI PMID:9789005 Folding in vivo of a newly translated yeast cytosolic enzyme...	MODIFY	Summary: PMID:9789005 showed that the SSA class of Hsp70 proteins assists folding of newly translated OTC in vivo. The IGI evidence comes from genetic interaction among SSA family members. GO:0051082 is now formally obsolete. Reason: GO:0051082 is now formally obsolete. PMID:9789005 actually demonstrates chaperone activity, not mere binding. The correct replacement is GO:0140662 (ATP-dependent protein folding chaperone). Proposed replacements: ATP-dependent protein folding chaperone Supporting Evidence: PMID:9789005 yeast cytosolic OTC is assisted to its native state by the SSA class of yeast cytosolic Hsp70 proteins
GO:0140662 ATP-dependent protein folding chaperone	IDA PMID:8947547 The refolding activity of the yeast heat shock proteins Ssa1...	NEW	Summary: SSA2 is an ATP-dependent protein folding chaperone. PMID:8947547 demonstrated that Ssa1/2p depletion dramatically reduced refolding of denatured luciferase in yeast cytosol, and PMID:9789005 showed SSA-dependent folding of newly translated OTC. GO:0140662 is the most specific and accurate MF term, replacing the obsoleting GO:0051082. UniProt already assigns this via InterPro (IEA). Reason: GO:0140662 (ATP-dependent protein folding chaperone) is the most specific and accurate molecular function term for SSA2. It replaces the obsoleting GO:0051082 and is more specific than GO:0044183. Supporting Evidence: PMID:8947547 These results demonstrate, for the first time, the refolding activity of Ssa1/2p in the context of the yeast cytosol PMID:9789005 yeast cytosolic OTC is assisted to its native state by the SSA class of yeast cytosolic Hsp70 proteins

Gene Description

Existing Annotations Review

Core Functions

References

Deep Research

Falcon

OpenScientist

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