SSZ1

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0005634 nucleus	IBA GO_REF:0000033	UNDECIDED	Summary: The inherited nucleus localization remains unresolved rather than disproved by the principal cytosolic ribosome association. Reason: GOA traces this assertion to PTN002500132. A main cytoplasmic RAC role and absence of a dedicated compartment-specific function do not demonstrate loss of secondary localization. Current PAINT retains nucleus at this node but lacks its older plasma-membrane assertion; the latter discrepancy alone does not establish biological exclusion. Focused evaluation of target localization, condition dependence and ancestral compartment evidence is pending. Propagation Review Root cause: UNRESOLVED Sources checked: PANTHER:PTN002500132 · PTN002500132 UNRESOLVED Secondary localization requires target/ancestral-context assessment; principal cytosolic residence is not a negative localization experiment.
GO:0005737 cytoplasm	IBA GO_REF:0000033	ACCEPT	Summary: The cytoplasm is the principal compartment of Ssz1/RAC cotranslational chaperoning. Reason: PMID:11274393 identifies cytoplasmic Ssz1-Zuo1 RAC on ribosomes, and PMID:10792726 provides the original localization evidence. The broader cytoplasm annotation remains a core property alongside cytosol and ribosome terms. Supporting Evidence: file:yeast/SSZ1/SSZ1-deep-research-falcon.md RAC is a ribosome-associated system localized near the 60S subunit tunnel exit region, with Zuo1 anchoring RAC at the ribosome and Ssz1 tethered through Zuo1.
GO:0005886 plasma membrane	IBA GO_REF:0000033	UNDECIDED	Summary: The inherited plasma membrane localization remains unresolved rather than disproved by the principal cytosolic ribosome association. Reason: GOA traces this assertion to PTN002500132. A main cytoplasmic RAC role and absence of a dedicated compartment-specific function do not demonstrate loss of secondary localization. Current PAINT retains nucleus at this node but lacks its older plasma-membrane assertion; the latter discrepancy alone does not establish biological exclusion. Focused evaluation of target localization, condition dependence and ancestral compartment evidence is pending. Propagation Review Root cause: UNRESOLVED Sources checked: PANTHER:PTN002500132 · PTN002500132 SOURCE STALE OR MISSING Secondary localization requires target/ancestral-context assessment; principal cytosolic residence is not a negative localization experiment.
GO:0016887 ATP hydrolysis activity	IBA GO_REF:0000033	REMOVE	Summary: Direct biochemical characterization detected no Ssz1 ATPase activity despite its retained ATP-binding capability. Reason: PMID:17901048 directly assays the atypical yeast Hsp70 and reports no ATPase activity in vitro; PMID:23202586 provides complementary structural evidence. This target-specific loss challenges the ATPase IBD at PTN000452648 and the electronic Hsp70-family mapping. The existing OpenScientist investigation reaches the same conclusion and identifies the decisive primary assay. Neither dispensability of ATP binding for growth nor the presence of a propagated annotation is itself the reason for rejection. ATP binding remains accepted, and no claim is made that every untested condition has been experimentally excluded. Propagation Review Root cause: PROPAGATION BAD Failure modes: PSEUDO OR SUBACTIVITY LOSS Sources checked: PANTHER:PTN000452648 · PTN000452648 SUPPORTS SOURCE BUT NOT TARGET Direct Ssz1 biochemical inactivity and structural specialization challenge retention of the ancestral Hsp70 ATPase function. Supporting Evidence: PMID:17901048 We now find that Ssz1 is not an ATPase in vitro file:yeast/SSZ1/SSZ1-hypotheses/function-hypothesis-go-0016887/openscientist.md The distinction between ATP binding (GO:0005524) and ATP hydrolysis activity (GO:0016887) is critical here.
GO:0031072 heat shock protein binding	IBA GO_REF:0000033	ACCEPT	Summary: Heat shock protein binding is real but broad: Ssz1 forms a stable heterodimer with the J-protein Zuo1 and functionally couples RAC to Ssb. The stable Zuo1 interaction distinguishes this from generic protein-binding calls, but binding alone does not describe the RAC mechanism. Reason: The stable Zuo1 partnership is an experimentally grounded molecular interaction central to RAC assembly; unlike bare protein binding, this term identifies the chaperone-system context of Ssz1's core role. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000452648 · PANTHER:PTN000452648 SUPPORTS TRANSFER Ssz1's stable partnership with the Zuo1 Hsp40 and functional coupling to Ssb support this conserved chaperone-system interaction. Supporting Evidence: file:yeast/SSZ1/SSZ1-deep-research-falcon.md Ssz1 forms a stable heterodimer with Zuo1, and this RAC module cooperates with Ssb1/2 (canonical Hsp70s) at the ribosome to support cotranslational folding. PMID:15908962 Ssz1's predominant function in the cell is to facilitate Zuo1's ability to function as a J-protein partner of Ssb on the ribosome
GO:0044183 protein folding chaperone	IBA GO_REF:0000033	ACCEPT	Summary: Ssz1 directly contacts nascent polypeptides and helps relay them from Zuo1 to Ssb. Reason: PMID:32198371 resolves an earlier uncertainty: chain-length-dependent crosslinking in Saccharomyces cerevisiae demonstrates Ssz1 contact with emerging nascent chains, preceding Ssb binding. Structural work explains transient low-affinity substrate handling. This directly supports the inherited protein-folding-chaperone function at PTN000452648; Ssz1 need not hydrolyze ATP itself to satisfy this broad term. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000452648 · PTN000452648 SUPPORTS TRANSFER Direct target nascent-chain binding and transfer support retained chaperone activity despite loss of canonical ATP hydrolysis. Supporting Evidence: PMID:32198371 Ssz1 is an active chaperone optimized for transient, low-affinity substrate binding
GO:0005829 cytosol	IBA GO_REF:0000033	ACCEPT	Summary: Cytosol is consistent with Ssz1/RAC being a ribosome-associated cytoplasmic complex. Kept as non-core relative to the more informative ribosome-associated localization. Reason: Cytosol is a core compartment for Ssz1/RAC, complemented by the more specific cytosolic-ribosome annotation. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN002500132 · PANTHER:PTN002500132 SUPPORTS TRANSFER Cytosol is a valid core family inference for Ssz1, complemented by its cytosolic-ribosome site of action. Supporting Evidence: file:yeast/SSZ1/SSZ1-deep-research-falcon.md RAC is a ribosome-associated system localized near the 60S subunit tunnel exit region, with Zuo1 anchoring RAC at the ribosome and Ssz1 tethered through Zuo1.
GO:0042026 protein refolding	IBA GO_REF:0000033	MODIFY	Summary: The current PAINT fungal revision supports broad protein folding in place of the older protein-refolding assertion. Reason: The pinned GOA row descends from PTN000452648. Current PAINT explicitly places NOT/IRD for GO:0042026 at fungal node PTN001065099 (2026-06-16), with PTN000452648 as its source, and carries the broader GO:0006457 protein-folding assertion through that same node. Current target leaf records retain that broader descent. Follow this node-specific generalization rather than replacing refolding with the sibling cotranslational-folding term merely because it is the best-studied role. The revision and primary folding evidence support MODIFY; they do not demonstrate zero refolding capacity under every biochemical condition. Propagation Review Root cause: SOURCE STALE OR MISSING Sources checked: PANTHER:PTN000452648 · PTN000452648 SOURCE STALE OR MISSING The ancestral refolding IBD remains, but descendant fungal PTN001065099 explicitly carries its NOT/IRD and generalized protein-folding assertion; the pinned leaf annotation predates this revision. Proposed replacements: protein folding
GO:0000166 nucleotide binding	IEA GO_REF:0000043	ACCEPT	Summary: Nucleotide binding is supported: Ssz1 binds ATP/nucleotide via its Hsp70 nucleotide-binding domain. Note, however, that this binding is functionally dispensable in vivo (extensive ATP-cleft mutants are functional), so it is not a core driver of its activity. Reason: Ssz1 binds nucleotide (ATP) via its conserved Hsp70 NBD, supported experimentally. Supporting Evidence: file:yeast/SSZ1/SSZ1-deep-research-falcon.md Ssz1 binds nucleotide but does not hydrolyze ATP detectably; ATP hydrolysis is dispensable in vivo, and even ATP-binding defects can be tolerated unless combined with other disabling mutations PMID:15908962 Ssz1 binds ATP, but none of the 11 different amino acid
GO:0005524 ATP binding	IEA GO_REF:0000120	ACCEPT	Summary: ATP binding is experimentally supported (Ssz1 binds ATP). The nucleotide-binding cleft is intact and occupied, although mutagenesis shows ATP binding is not required for Ssz1's in vivo function. Retained as a real biochemical property. Reason: Ssz1 binds ATP via its Hsp70 NBD (directly demonstrated), even though this is dispensable for function. Supporting Evidence: PMID:15908962 Ssz1 binds ATP, but none of the 11 different amino acid file:yeast/SSZ1/SSZ1-deep-research-falcon.md Ssz1 binds nucleotide but does not hydrolyze ATP detectably; ATP hydrolysis is dispensable in vivo, and even ATP-binding defects can be tolerated unless combined with other disabling mutations
GO:0005737 cytoplasm	IEA GO_REF:0000044	ACCEPT	Summary: The cytoplasm is the principal compartment of Ssz1/RAC cotranslational chaperoning. Reason: PMID:11274393 identifies cytoplasmic Ssz1-Zuo1 RAC on ribosomes, and PMID:10792726 provides the original localization evidence. The broader cytoplasm annotation remains a core property alongside cytosol and ribosome terms. Supporting Evidence: file:yeast/SSZ1/SSZ1-deep-research-falcon.md RAC is a ribosome-associated system localized near the 60S subunit tunnel exit region, with Zuo1 anchoring RAC at the ribosome and Ssz1 tethered through Zuo1.
GO:0016887 ATP hydrolysis activity	IEA GO_REF:0000002	REMOVE	Summary: Direct biochemical characterization detected no Ssz1 ATPase activity despite its retained ATP-binding capability. Reason: PMID:17901048 directly assays the atypical yeast Hsp70 and reports no ATPase activity in vitro; PMID:23202586 provides complementary structural evidence. This target-specific loss challenges the ATPase IBD at PTN000452648 and the electronic Hsp70-family mapping. The existing OpenScientist investigation reaches the same conclusion and identifies the decisive primary assay. Neither dispensability of ATP binding for growth nor the presence of a propagated annotation is itself the reason for rejection. ATP binding remains accepted, and no claim is made that every untested condition has been experimentally excluded. Supporting Evidence: PMID:17901048 We now find that Ssz1 is not an ATPase in vitro file:yeast/SSZ1/SSZ1-hypotheses/function-hypothesis-go-0016887/openscientist.md The distinction between ATP binding (GO:0005524) and ATP hydrolysis activity (GO:0016887) is critical here.
GO:0005515 protein binding	IPI PMID:11274393 RAC, a stable ribosome-associated complex in yeast formed by...	MODIFY	Summary: Ssz1 binds its Hsp40 partner Zuo1 in the functional ribosome-associated chaperone complex. Reason: The cited RAC characterization/structure establishes association of the atypical Hsp70 Ssz1 with Hsp40 Zuo1, supporting the existing informative heat shock protein binding function rather than unrestricted protein binding. This replacement identifies the chaperone-partner interaction without inferring an untested enzymatic activity. Proposed replacements: heat shock protein binding Supporting Evidence: PMID:11274393 Zuotin and Ssz1p form a ribosome-associated complex (RAC)
GO:0005515 protein binding	IPI PMID:15766533 Navigating the chaperone network: an integrative map of phys...	REMOVE	Summary: Generic protein binding from a Hsp90 chaperone-network interaction map; uninformative as a molecular function term. Reason: Remove the uninformative generic protein binding label while retaining the reported interaction evidence. The chaperone-partner and nascent-chain functions have informative annotations; a broad proteomic association does not alone justify an additional specific molecular function.
GO:0005515 protein binding	IPI PMID:16429126 Proteome survey reveals modularity of the yeast cell machine...	REMOVE	Summary: Generic protein binding from a proteome modularity survey; uninformative as a molecular function term. Reason: Remove the uninformative generic protein binding label while retaining the reported interaction evidence. The chaperone-partner and nascent-chain functions have informative annotations; a broad proteomic association does not alone justify an additional specific molecular function.
GO:0005515 protein binding	IPI PMID:16554755 Global landscape of protein complexes in the yeast Saccharom...	REMOVE	Summary: Generic protein binding from a global protein-complex landscape study; uninformative as a molecular function term. Reason: Remove the uninformative generic protein binding label while retaining the reported interaction evidence. The chaperone-partner and nascent-chain functions have informative annotations; a broad proteomic association does not alone justify an additional specific molecular function.
GO:0005515 protein binding	IPI PMID:19536198 An atlas of chaperone-protein interactions in Saccharomyces ...	REMOVE	Summary: Generic protein binding from a chaperone-protein interaction atlas; uninformative as a molecular function term. Reason: Remove the uninformative generic protein binding label while retaining the reported interaction evidence. The chaperone-partner and nascent-chain functions have informative annotations; a broad proteomic association does not alone justify an additional specific molecular function.
GO:0005515 protein binding	IPI PMID:23202586 Structural characterization of a eukaryotic chaperone--the r...	MODIFY	Summary: Ssz1 binds its Hsp40 partner Zuo1 in the functional ribosome-associated chaperone complex. Reason: The cited RAC characterization/structure establishes association of the atypical Hsp70 Ssz1 with Hsp40 Zuo1, supporting the existing informative heat shock protein binding function rather than unrestricted protein binding. This replacement identifies the chaperone-partner interaction without inferring an untested enzymatic activity. Proposed replacements: heat shock protein binding Supporting Evidence: PMID:11274393 Zuotin and Ssz1p form a ribosome-associated complex (RAC)
GO:0005515 protein binding	IPI PMID:37070168 RNA-dependent interactome allows network-based assignment of...	REMOVE	Summary: Generic protein binding from a RNA-dependent interactome study; uninformative as a molecular function term. Reason: Remove the uninformative generic protein binding label while retaining the reported interaction evidence. The chaperone-partner and nascent-chain functions have informative annotations; a broad proteomic association does not alone justify an additional specific molecular function.
GO:0005515 protein binding	IPI PMID:37968396 The social and structural architecture of the yeast protein ...	REMOVE	Summary: Generic protein binding from a yeast interactome architecture study; uninformative as a molecular function term. Reason: Remove the uninformative generic protein binding label while retaining the reported interaction evidence. The chaperone-partner and nascent-chain functions have informative annotations; a broad proteomic association does not alone justify an additional specific molecular function.
GO:0006450 regulation of translational fidelity	IDA PMID:15456889 The ribosome-bound chaperones RAC and Ssb1/2p are required f...	ACCEPT	Summary: Strongly supported core biological process. RAC (Ssz1+Zuo1) and Ssb1/2 are required for accurate translation; their absence impairs translational fidelity (primarily translation termination) and confers paromomycin/aminoglycoside hypersensitivity. Reason: Direct experimental evidence that RAC/Ssz1 is required for translational fidelity; a core function. Supporting Evidence: PMID:15456889 RAC and Ssb1/2p are crucial in maintaining file:yeast/SSZ1/SSZ1-deep-research-falcon.md Ssz1 contributes to accurate translation; RAC/Ssz1 defects produce paromomycin/aminoglycoside sensitivity and translational-fidelity phenotypes.
GO:0006457 protein folding	NAS PMID:11274393 RAC, a stable ribosome-associated complex in yeast formed by...	ACCEPT	Summary: Protein folding (broad BP) is consistent with RAC's chaperone-like effect on nascent chains during translation. Retained at the broad level; the more specific and accurate process term is 'de novo' cotranslational protein folding. Reason: Ssz1 participates in protein folding cotranslationally as part of RAC; broad BP term retained. Supporting Evidence: PMID:11274393 the 1:1 complex is stable, even in the presence of ATP or ADP file:yeast/SSZ1/SSZ1-deep-research-falcon.md RAC cooperates with the ribosome-bound canonical Hsp70 Ssb1/2 to form a functional chaperone triad that supports early nascent-chain handling and cotranslational folding.
GO:0051083 'de novo' cotranslational protein folding	IDA PMID:11274393 RAC, a stable ribosome-associated complex in yeast formed by...	ACCEPT	Summary: Well supported and the most accurate process term for Ssz1: RAC acts on nascent chains at the ribosomal exit tunnel during translation, relaying substrates toward Ssb capture. A core biological process. Reason: Ssz1/RAC functions in cotranslational (de novo) folding of nascent chains at the ribosome; core BP. Supporting Evidence: file:yeast/SSZ1/SSZ1-deep-research-falcon.md a translation rate of about 3–6 aa/s PMID:11929994 Ssb1/2p, Ssz1p, and zuotin act in concert on
GO:0051082 unfolded protein binding	IMP PMID:11054575 Yeast Pdr13p and Zuo1p molecular chaperones are new function...	MODIFY	Summary: Direct nascent-chain binding is now demonstrated for Ssz1 and is captured by protein folding chaperone. Reason: Live QuickGO inspection confirms GO:0051082 is obsolete. The old rejection overinterpreted dispensability of the peptide-binding domain as absence of client binding. PMID:32198371 directly demonstrates transient Ssz1-nascent-chain contacts and handover to Ssb, resolving that mechanistic issue. Replace the obsolete binding label with the already-supported GO:0044183 chaperone function, without falsely attributing the later experiment to the original PMID:11054575 study. Proposed replacements: protein folding chaperone Supporting Evidence: PMID:32198371 Ssz1 is an active chaperone optimized for transient, low-affinity substrate binding
GO:0051083 'de novo' cotranslational protein folding	IMP PMID:11274393 RAC, a stable ribosome-associated complex in yeast formed by...	ACCEPT	Summary: Duplicate of the cotranslational folding annotation, here with IMP evidence. Consistently accepted: a core biological process for Ssz1/RAC. Reason: Ssz1/RAC functions in cotranslational (de novo) folding of nascent chains at the ribosome; core BP. Supporting Evidence: file:yeast/SSZ1/SSZ1-deep-research-falcon.md Ssz1 operates as part of RAC to organize and regulate cotranslational chaperoning at the ribosomal exit tunnel PMID:11929994 Ssb1/2p, Ssz1p, and zuotin act in concert on
GO:0006452 translational frameshifting	IMP PMID:16607023 Specific effects of ribosome-tethered molecular chaperones o...	KEEP AS NON CORE	Summary: Supported: ribosome-tethered chaperones including RAC/Ssz1 have specific effects on programmed -1 ribosomal frameshifting, consistent with Ssz1's role at the translating ribosome influencing translational accuracy. Kept as a non-core specialized readout of its cotranslational/fidelity function. Reason: Effect on programmed frameshifting is a specialized consequence of Ssz1/RAC action at the ribosome; valid but not the central function. Supporting Evidence: file:yeast/SSZ1/SSZ1-deep-research-falcon.md Ssz1 contributes to a function related to translational fidelity, and defects in Ssz1/RAC are associated with sensitivity to paromomycin/aminoglycosides
GO:0002181 cytoplasmic translation	IMP PMID:11929994 A functional chaperone triad on the yeast ribosome.	KEEP AS NON CORE	Summary: Cytoplasmic translation is consistent with Ssz1/RAC acting on the cytoplasmic translating ribosome as part of the cotranslational chaperone triad with Ssb. Retained as a non-core broad process; the more specific roles are cotranslational folding and translational fidelity. Reason: Ssz1 acts at the cytoplasmic translating ribosome; broad process retained as non-core relative to its specific cotranslational-folding/fidelity roles. Supporting Evidence: PMID:11929994 Ssb1/2p, Ssz1p, and zuotin act in concert on file:yeast/SSZ1/SSZ1-deep-research-falcon.md RAC cooperates with the ribosome-bound canonical Hsp70 Ssb1/2 to form a functional chaperone triad that supports early nascent-chain handling and cotranslational folding.
GO:0005737 cytoplasm	IDA PMID:10792726 Hyperactive forms of the Pdr1p transcription factor fail to ...	ACCEPT	Summary: The cytoplasm is the principal compartment of Ssz1/RAC cotranslational chaperoning. Reason: PMID:11274393 identifies cytoplasmic Ssz1-Zuo1 RAC on ribosomes, and PMID:10792726 provides the original localization evidence. The broader cytoplasm annotation remains a core property alongside cytosol and ribosome terms. Supporting Evidence: file:yeast/SSZ1/SSZ1-deep-research-falcon.md RAC is a ribosome-associated system localized near the 60S subunit tunnel exit region, with Zuo1 anchoring RAC at the ribosome and Ssz1 tethered through Zuo1.
GO:0006364 rRNA processing	IMP PMID:20368619 A ribosome-anchored chaperone network that facilitates eukar...	KEEP AS NON CORE	Summary: rRNA processing is an indirect/pleiotropic consequence: the ribosome-anchored chaperone network (including RAC) facilitates eukaryotic ribosome biogenesis, so loss of Ssz1 can perturb rRNA processing. This is not a direct molecular role of Ssz1 in cleaving/modifying rRNA; kept as non-core to reflect the downstream biogenesis effect. Reason: rRNA processing defect is a downstream consequence of impaired ribosome-associated chaperoning, not a direct Ssz1 enzymatic role; retained as non-core. Supporting Evidence: file:yeast/SSZ1/SSZ1-deep-research-falcon.md Ssz1 is the Hsp70 subunit of the ribosome-associated complex (RAC)
GO:0006450 regulation of translational fidelity	IMP PMID:15456889 The ribosome-bound chaperones RAC and Ssb1/2p are required f...	ACCEPT	Summary: Duplicate of the translational-fidelity annotation, here with IMP evidence. Consistently accepted as a core biological process: RAC/Ssz1 is required for accurate translation (especially translation termination) and its loss confers paromomycin sensitivity. Reason: Direct experimental (IMP) evidence that RAC/Ssz1 is required for translational fidelity; a core function. Supporting Evidence: PMID:15456889 hypersensitivity against the aminoglycoside paromomycin file:yeast/SSZ1/SSZ1-deep-research-falcon.md Ssz1 contributes to accurate translation; RAC/Ssz1 defects produce paromomycin/aminoglycoside sensitivity and translational-fidelity phenotypes.
GO:0022626 cytosolic ribosome	IDA PMID:11274393 RAC, a stable ribosome-associated complex in yeast formed by...	NEW	Summary: Proposed new annotation for the cytosolic ribosome where Ssz1 acts as the stable Hsp70-like subunit of RAC. Reason: PMID:11274393 identifies Ssz1 and Zuo1 as a stable 1:1 ribosome-associated complex, with Zuo1 providing the ribosome anchor. The current SSZ1 GOA set contains only broad cytoplasm/cytosol localizations and lacks this informative site-of-action annotation. Supporting Evidence: PMID:11274393 Zuotin and Ssz1p form a ribosome-associated complex (RAC) that is bound to the ribosome via the zuotin subunit.

Gene Description

Existing Annotations Review

Core Functions

References

Deep Research

Falcon

OpenScientist

OpenScientist

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