CCT8 encodes the theta subunit of the cytosolic chaperonin-containing T-complex (CCT/TRiC). CCT/TRiC is an ATP-dependent hetero-oligomeric chaperonin formed from eight related subunits in each ring. The assembled complex folds actin, tubulin, and other cytosolic proteins. CCT8 should therefore be interpreted primarily as a CCT/TRiC subunit, not as a free generic protein-binding factor.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0006457 protein folding | IBA GO_REF:0000033 | ACCEPT | Summary: CCT8 is a CCT/TRiC subunit and supports the protein-folding activity of the assembled chaperonin. Reason: Yeast CCT catalyzes actin folding, and PTHR11353 places CCT8 in the conserved chaperonin family. Supporting Evidence: PMID:16762366 Yeast CCT catalyses the folding of yeast ACT1p and human beta-actin with nearly identical rate constants and yields. file:interpro/panther/PTHR11353/PTHR11353-metadata.yaml PANTHER PTHR11353 classifies CCT8 in the chaperonin family. file:yeast/CCT8/CCT8-deep-research-falcon.md Falcon synthesis supports CCT8 as the CCT/TRiC theta subunit with conserved ATP-dependent chaperonin function. |
| GO:0005832 chaperonin-containing T-complex | IBA GO_REF:0000033 | ACCEPT | Summary: CCT8 is an integral component of the chaperonin-containing T-complex. Reason: The CCT complex is built from Cct1p-Cct8p subunits; CCT8 is the theta subunit of that complex. 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, which are denoted Cct1p-Cct8p. |
| GO:0051082 unfolded protein binding | IBA GO_REF:0000033 | MODIFY | Summary: Generic unfolded-protein binding should be replaced by a chaperone term. Reason: CCT8 acts through ATP-dependent CCT/TRiC-mediated folding; GO:0140662 is more informative than generic unfolded protein binding. Proposed replacements: ATP-dependent protein folding chaperone |
| GO:0000166 nucleotide binding | IEA GO_REF:0000043 | ACCEPT | Summary: Nucleotide binding is consistent with the conserved CCT chaperonin ATPase fold. Reason: The CCT family uses ATP binding and hydrolysis during substrate folding, so the keyword-derived term is retained as a valid molecular feature. |
| GO:0005524 ATP binding | IEA GO_REF:0000120 | ACCEPT | Summary: ATP binding is consistent with the ATP-dependent CCT/TRiC mechanism. Reason: CCT is an ATP-dependent protein-folding machine and CCT8 is a subunit of that complex. Supporting Evidence: PMID:16762366 The eukaryotic cytosolic chaperonin CCT is an essential ATP-dependent protein folding machine. |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: CCT8 functions in the cytosolic CCT/TRiC chaperonin. Reason: CCT/TRiC folds cytosolic substrates such as actin and tubulin, and UniProt places CCT8 in the cytoplasm. |
| GO:0005832 chaperonin-containing T-complex | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA annotation to the CCT complex is consistent with CCT8 subunit identity. Reason: The complex term is supported by the known Cct1p-Cct8p composition of CCT/TRiC. |
| GO:0006457 protein folding | IEA GO_REF:0000120 | ACCEPT | Summary: Protein folding is the core process mediated by CCT/TRiC. Reason: This broad BP term is retained because CCT8 contributes to the assembled CCT complex that catalyzes substrate folding. |
| GO:0016887 ATP hydrolysis activity | IEA GO_REF:0000002 | ACCEPT | Summary: ATP hydrolysis activity is consistent with CCT/TRiC chaperonin mechanism. Reason: The InterPro/PANTHER chaperonin family supports the conserved ATPase fold used during CCT-mediated substrate folding. |
| GO:0051082 unfolded protein binding | IEA GO_REF:0000120 | MODIFY | Summary: Generic unfolded-protein binding is less specific than CCT/TRiC chaperone activity. Reason: Replace with GO:0140662 because CCT8 substrate engagement occurs as part of an ATP-dependent folding chaperonin. Proposed replacements: ATP-dependent protein folding chaperone |
| GO:0140662 ATP-dependent protein folding chaperone | IEA GO_REF:0000002 | ACCEPT | Summary: ATP-dependent protein folding chaperone is the most informative MF annotation for CCT8-containing CCT/TRiC. Reason: CCT/TRiC is an ATP-dependent folding machine, and CCT8 is a core subunit of that complex. Supporting Evidence: PMID:16762366 The eukaryotic cytosolic chaperonin CCT is an essential ATP-dependent protein folding machine. |
| GO:0005515 protein binding | IPI PMID:11805837 Systematic identification of protein complexes in Saccharomy... | MARK AS OVER ANNOTATED | Summary: Protein binding is too generic for CCT8 and should not be treated as core. Reason: Large-scale complex evidence supports CCT complex membership but not a distinct generic protein-binding function beyond chaperonin activity. |
| GO:0005515 protein binding | IPI PMID:16554755 Global landscape of protein complexes in the yeast Saccharom... | MARK AS OVER ANNOTATED | Summary: Generic protein binding from complex-scale data is not informative for CCT8. Reason: The specific curated functions are CCT complex membership and ATP-dependent chaperonin-mediated folding. |
| GO:0005515 protein binding | IPI PMID:19536198 An atlas of chaperone-protein interactions in Saccharomyces ... | MARK AS OVER ANNOTATED | Summary: Chaperone interactome evidence does not justify a generic protein-binding annotation. Reason: PMID:19536198 reports broad TAP-tag chaperone interactions that are often indirect; the more precise function is CCT/TRiC chaperonin activity. Supporting Evidence: PMID:19536198 The interactions presented are indirect TAP-tag based interactions and not direct binary interactions. |
| GO:0005515 protein binding | IPI PMID:21734642 Combinatorial depletion analysis to assemble the network arc... | MARK AS OVER ANNOTATED | Summary: SAGA/ADA depletion interaction evidence is peripheral to CCT8's chaperonin role. Reason: This interaction evidence does not define a specific CCT8 binding activity and is better left subordinate to chaperone annotations. |
| GO:0006457 protein folding | IDA PMID:16762366 Quantitative actin folding reactions using yeast CCT purifie... | ACCEPT | Summary: Direct biochemical evidence supports CCT-mediated protein folding. Reason: Purified yeast CCT folds actin in vitro; CCT8 contributes as a core subunit of that complex. Supporting Evidence: PMID:16762366 Yeast CCT catalyses the folding of yeast ACT1p and human beta-actin with nearly identical rate constants and yields. |
| GO:0005737 cytoplasm | HDA PMID:11914276 Subcellular localization of the yeast proteome. | ACCEPT | Summary: HDA localization to cytoplasm is consistent with the cytosolic CCT/TRiC complex. Reason: CCT/TRiC acts on cytosolic substrates and UniProt describes CCT8 as cytoplasmic. |
| GO:0005832 chaperonin-containing T-complex | IPI PMID:15704212 Physiological effects of unassembled chaperonin Cct subunits... | ACCEPT | Summary: Interaction evidence supports CCT8 membership in CCT/TRiC. Reason: The CCT complex is composed of Cct1p-Cct8p, and CCT8 is the theta subunit. |
| GO:0005832 chaperonin-containing T-complex | IDA PMID:16762366 Quantitative actin folding reactions using yeast CCT purifie... | ACCEPT | Summary: Direct purification of yeast CCT supports this cellular component annotation. Reason: The IDA evidence derives from purified yeast CCT, so the assembled complex term is accurate. |
| GO:0051082 unfolded protein binding | IDA PMID:16762366 Quantitative actin folding reactions using yeast CCT purifie... | MODIFY | Summary: The IDA evidence supports chaperonin-mediated folding rather than generic unfolded-protein binding. Reason: Replace with GO:0140662 because CCT8 acts in the ATP-dependent CCT/TRiC protein-folding chaperone complex. Proposed replacements: ATP-dependent protein folding chaperone |
Loading supporting content…
Download this section (compressed HTML)Q: Does the CCT8/theta subunit contribute any substrate-specific contacts that differ from other yeast CCT subunits?
Experiment: Map substrate contacts in yeast CCT/TRiC by crosslinking folded substrates under CCT8-specific perturbation and comparing with other CCT subunits.
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)