CCT3

UniProt ID: P39077
Organism: Saccharomyces cerevisiae S288C
Review Status: COMPLETE
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Gene Description

CCT3 encodes the gamma subunit of the cytosolic group II chaperonin TRiC/CCT. As one of eight obligate paralogous subunits in each ring, Cct3 contributes ATPase and substrate-contact surfaces to the hetero-oligomeric folding chamber that matures actin, tubulin, and other cytosolic clients. Its curated core function is complex-level ATP-dependent protein folding, not nonspecific protein binding.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0006457 protein folding
IBA
GO_REF:0000033
ACCEPT
Summary: CCT3 participates in protein folding as an obligate subunit of TRiC/CCT, the cytosolic chaperonin that folds actin, tubulin, and other clients.
Reason: Protein folding is the correct biological-process context for the chaperonin complex, supported by direct yeast CCT actin-folding assays and PANTHER/InterPro family evidence.
Supporting Evidence:
file:yeast/CCT3/CCT3-deep-research-falcon.md
The CCT/TRiC complex is a double-ring ATP-driven folding machine
GO:0005832 chaperonin-containing T-complex
IBA
GO_REF:0000033
ACCEPT
Summary: CCT3 is a named subunit of the chaperonin-containing T-complex.
Reason: Complex membership is central to the gene product function and is supported by yeast CCT complex literature and family evidence.
GO:0051082 unfolded protein binding
IBA
GO_REF:0000033
MODIFY
Summary: GO:0051082 is formally obsolete; Cct3 contributes to the CCT/TRiC complex's ATP-dependent protein-folding chaperone activity.
Reason: GO:0051082 "unfolded protein binding" is obsolete with GO:0044183 protein folding chaperone and GO:0140309 unfolded protein holdase activity as consider terms. For Cct3, the evidence supports the GO:0140662 ATP-dependent protein folding chaperone activity of the CCT/TRiC complex; because Cct3 is one subunit of that complex, any final GOA replacement with GO:0140662 should use the contributes_to qualifier.
Propagation Review
Root cause: SOURCE STALE OR MISSING
Sources checked:
PANTHER:PTN004253040 Β· PAINT chaperonin node SOURCE STALE OR MISSING
The current PTHR11353 PAINT record retains this node for conserved CCT/TRiC protein-folding biology, but it no longer carries obsolete GO:0051082 as a molecular-function IBD.
GO:0000166 nucleotide binding
IEA
GO_REF:0000043
MODIFY
Summary: nucleotide binding is a true but overly broad family/keyword annotation for CCT3; ATP binding, ATP hydrolysis, and ATP-dependent chaperone annotations capture the specific chemistry.
Reason: Nucleotide binding is too general; Cct3 carries a conserved chaperonin ATP-binding/hydrolysis domain, so GO:0005524 ATP binding and GO:0016887 ATP hydrolysis activity capture the relevant ATPase-cycle molecular functions more precisely.
GO:0005524 ATP binding
IEA
GO_REF:0000120
ACCEPT
Summary: CCT3 contains a conserved chaperonin ATP-binding site, but ATP binding alone is a domain property rather than the core biological function.
Reason: Retain as a direct Cct3 subunit molecular function supported by conserved CCT/TRiC equatorial ATPase-domain biology.
GO:0005737 cytoplasm
IEA
GO_REF:0000044
ACCEPT
Summary: CCT3 functions as part of the cytosolic TRiC/CCT chaperonin.
Reason: Cytoplasm is the established location of the CCT/TRiC folding machine.
GO:0005832 chaperonin-containing T-complex
IEA
GO_REF:0000117
ACCEPT
Summary: CCT3 is a named subunit of the chaperonin-containing T-complex.
Reason: Complex membership is central to the gene product function and is supported by yeast CCT complex literature and family evidence.
GO:0006457 protein folding
IEA
GO_REF:0000120
ACCEPT
Summary: CCT3 participates in protein folding as an obligate subunit of TRiC/CCT, the cytosolic chaperonin that folds actin, tubulin, and other clients.
Reason: Protein folding is the correct biological-process context for the chaperonin complex, supported by direct yeast CCT actin-folding assays and PANTHER/InterPro family evidence.
GO:0016887 ATP hydrolysis activity
IEA
GO_REF:0000002
ACCEPT
Summary: CCT3 is a TCP-1/CCT chaperonin subunit with conserved ATPase machinery that powers TRiC/CCT conformational cycling.
Reason: ATP hydrolysis is a defensible subunit-level molecular function for CCT family members and is directly tied to the chaperonin folding cycle.
GO:0051082 unfolded protein binding
IEA
GO_REF:0000120
MODIFY
Summary: This retired GO_REF:0000120 row used obsolete GO:0051082; the CCT/TRiC complex-level replacement is ATP-dependent protein folding chaperone activity.
Reason: GO:0051082 "unfolded protein binding" is obsolete with GO:0044183 protein folding chaperone and GO:0140309 unfolded protein holdase activity as consider terms. For Cct3, the evidence supports the GO:0140662 ATP-dependent protein folding chaperone activity of the CCT/TRiC complex; because Cct3 is one subunit of that complex, any final GOA replacement with GO:0140662 should use the contributes_to qualifier.
GO:0140662 ATP-dependent protein folding chaperone
IEA
GO_REF:0000002
ACCEPT
Summary: CCT3 is an obligate subunit of the ATP-dependent TRiC/CCT folding machine.
Reason: The term is appropriate as a complex-level chaperonin function; in the synthesized core function it is modeled as a contributed-to molecular function rather than a standalone activity of an isolated subunit.
Supporting Evidence:
PMID:16762366
The eukaryotic cytosolic chaperonin CCT is an essential ATP-dependent protein folding machine whose action is required for folding the cytoskeletal proteins actin and tubulin
GO:0005515 protein binding
IPI
PMID:19536198
An atlas of chaperone-protein interactions in Saccharomyces ...
REMOVE
Summary: The CCT3-EFT2 interaction is not enough to make generic protein binding an informative molecular-function annotation for Cct3.
Reason: The EFT2 interaction is useful physical-interaction context, but it does not define a specific replacement binding activity for this TRiC/CCT subunit; the generic protein-binding annotation should be removed in favor of Cct3's accepted chaperonin-complex and ATP-dependent folding activities.
Supporting Evidence:
PMID:19536198
It should be emphasized that the interactions presented are indirect TAP-tag based interactions and not direct binary interactions.
GO:0005515 protein binding
IPI
PMID:37968396
The social and structural architecture of the yeast protein ...
REMOVE
Summary: The proteome-scale profile-correlation map recovers CCT biology but does not make GO:0005515 an informative standalone Cct3 function.
Reason: This proteome-scale map recovered CCT proteins by profile correlation and helped place them in the TRiC/CCT assembly despite tag-dependent recovery limits, but it does not define an informative molecular binding function beyond the established chaperonin activity.
GO:0006457 protein folding
IDA
PMID:16762366
Quantitative actin folding reactions using yeast CCT purifie...
ACCEPT
Summary: CCT3 participates in protein folding as an obligate subunit of TRiC/CCT, the cytosolic chaperonin that folds actin, tubulin, and other clients.
Reason: Protein folding is the correct biological-process context for the chaperonin complex, supported by direct yeast CCT actin-folding assays and PANTHER/InterPro family evidence.
Supporting Evidence:
PMID:16762366
The eukaryotic cytosolic chaperonin CCT is an essential ATP-dependent protein folding machine whose action is required for folding the cytoskeletal proteins actin and tubulin
GO:0005832 chaperonin-containing T-complex
IPI
PMID:15704212
Physiological effects of unassembled chaperonin Cct subunits...
ACCEPT
Summary: CCT3 is a named subunit of the chaperonin-containing T-complex.
Reason: Complex membership is central to the gene product function and is supported by yeast CCT complex literature and family evidence.
Supporting Evidence:
PMID:15704212
which is composed of a stoichiometric array of eight different subunits, which are denoted Cct1p-Cct8p
GO:0005832 chaperonin-containing T-complex
IDA
PMID:16762366
Quantitative actin folding reactions using yeast CCT purifie...
ACCEPT
Summary: CCT3 is a named subunit of the chaperonin-containing T-complex.
Reason: Complex membership is central to the gene product function and is supported by yeast CCT complex literature and family evidence.
Supporting Evidence:
PMID:15704212
Eukaryotic chaperonins, the Cct complexes, are assembled into two rings, each of which is composed of a stoichiometric array of eight different subunits
GO:0051082 unfolded protein binding
IDA
PMID:16762366
Quantitative actin folding reactions using yeast CCT purifie...
MODIFY
Summary: The CCT3-tagged yeast complex supports CCT/TRiC foldase function, not a standalone obsolete unfolded-protein-binding activity for Cct3.
Reason: GO:0051082 "unfolded protein binding" is obsolete with GO:0044183 protein folding chaperone and GO:0140309 unfolded protein holdase activity as consider terms. For Cct3, the actin-folding evidence supports the GO:0140662 ATP-dependent protein folding chaperone activity of the CCT/TRiC complex; because Cct3 is one subunit of that complex, any final GOA replacement with GO:0140662 should use the contributes_to qualifier.
Supporting Evidence:
PMID:16762366
The eukaryotic cytosolic chaperonin CCT is an essential ATP-dependent protein folding machine whose action is required for folding the cytoskeletal proteins actin and tubulin
GO:0005524 ATP binding
IEA
GO_REF:0000002
ACCEPT
Summary: The current InterPro row correctly captures Cct3 ATP binding through the conserved CCT/TRiC chaperonin ATPase domain.
Reason: Cct3 is a group II chaperonin subunit with an equatorial ATP-binding site; ATP binding is a direct subunit activity coupled to CCT/TRiC conformational cycling.
Supporting Evidence:
file:yeast/CCT3/CCT3-deep-research-falcon.md
nucleotide-binding equatorial domains
GO:0005832 chaperonin-containing T-complex
IPI
PMID:21701561
The crystal structure of yeast CCT reveals intrinsic asymmet...
ACCEPT
Summary: The yeast CCT-actin crystal structure supports Cct3 as a physical subunit of the chaperonin-containing T-complex.
Reason: Cct3 is one of the eight ordered CCT/TRiC subunits resolved in the yeast CCT-actin structure, so this ComplexPortal structural row directly supports the CCT complex-membership assertion.
Supporting Evidence:
PMID:21701561
We have solved the crystal structure of yeast CCT in complex with actin at 3.8 Γ… resolution, revealing the subunit organisation

Core Functions

CCT3 is the gamma subunit of the cytosolic TRiC/CCT chaperonin. The subunit contributes ATPase and substrate-contact surfaces to the hetero-oligomeric double-ring complex, whose ATP-dependent conformational cycle folds actin, tubulin, and other cytosolic client proteins. The synthesized function is modeled as subunit ATP hydrolysis contributing to the complex-level ATP-dependent protein folding chaperone activity.

Molecular Function:
ATP hydrolysis activity
Directly Involved In:
Cellular Locations:
Supporting Evidence:
  • PMID:16762366
    The eukaryotic cytosolic chaperonin CCT is an essential ATP-dependent protein folding machine whose action is required for folding the cytoskeletal proteins actin and tubulin
  • PMID:15704212
    Eukaryotic chaperonins, the Cct complexes, are assembled into two rings, each of which is composed of a stoichiometric array of eight different subunits

References

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Suggested Questions for Experts

Q: Which yeast client proteins depend specifically on Cct3 apical-domain contacts rather than on generic TRiC/CCT chamber activity?

Suggested Experiments

Experiment: Profile client aggregation, solubility, and folding reporter behavior in conditional CCT3 mutants under permissive and restrictive conditions, with actin and tubulin reporters as controls.

Hypothesis: Cct3 contributes subunit-specific contacts for a subset of aggregation-prone or Q/N-rich clients.

Type: conditional mutant proteostasis profiling

Deep Research

Falcon

(CCT3-deep-research-falcon.md)

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SGD

(CCT3-deep-research-sgd.md)
SGD gene description for CCT3 (yeast) SGD

SGD gene description for CCT3 (yeast)

Subunit of the cytosolic chaperonin Cct ring complex; related to Tcp1p, required for the assembly of actin and tubulins in vivo; capable of binding Q/N rich proteins and mediating their folding

πŸ“š Additional Documentation

Notes

(CCT3-notes.md)

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