CCT2: Chaperonin Containing TCP1 Subunit 2
A key molecular chaperone in protein folding and cellular homeostasis
Gene Information Card
| Symbol | CCT2 |
|---|---|
| Full Name | Chaperonin Containing TCP1 Subunit 2 |
| Gene Type | Protein coding |
| Chromosomal Location | 12q15 |
| NCBI Gene ID | 10576 ncbi.nlm.nih.gov/gene/10576 |
| Ensembl ID | ENSG00000166226 |
| UniProt ID | P78371 |
| OMIM ID | 605139 |
| HGNC ID | 1615 |
| Aliases | CCTB, TCP-1-beta, CCT-beta, 99D8.1 |
Description
CCT2 encodes the beta subunit of the eukaryotic chaperonin containing TCP1 (CCT) complex, a group II chaperonin essential for the ATP-dependent folding of cytosolic proteins, including actin and tubulin. The CCT complex is composed of eight distinct subunits (CCT1-8) that form a double-ring structure. CCT2 is involved in cellular processes such as cell cycle progression, cytoskeletal organization, and response to stress. Mutations and altered expression of CCT2 have been implicated in various cancers and neurodegenerative disorders.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Hereditary spastic paraplegia (HSP) | CCT2 mutations impair protein folding capacity, leading to axonal degeneration | ClinVar: pathogenic variants reported |
| Colorectal cancer | CCT2 overexpression promotes cell proliferation and metastasis via enhanced folding of oncoproteins | COSMIC: somatic mutations and copy number gains |
| Breast cancer | CCT2 upregulation correlates with poor prognosis and chemoresistance | PubMed: expression analysis |
| Alzheimer's disease | CCT2 dysfunction contributes to tau aggregation and proteotoxicity | UniProt: interaction with tau |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Brain | 28.5 | High |
| Testis | 22.3 | High |
| Liver | 18.7 | Medium |
| Heart | 15.2 | Medium |
| Lung | 12.1 | Medium |
| Pancreas | 9.8 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 32.4 | Cervical cancer cell line |
| HEK293 | 29.1 | Embryonic kidney cells |
| HepG2 | 25.6 | Hepatocellular carcinoma |
| MCF7 | 21.3 | Breast cancer cell line |
| A549 | 18.9 | Lung adenocarcinoma |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1135C>T (p.Arg379Cys) | Missense | <0.01% | Loss of ATPase activity; associated with HSP |
| c.1492G>A (p.Glu498Lys) | Missense | <0.01% | Impaired complex assembly; pathogenic in HSP |
| c.1246A>G (p.Thr416Ala) | Missense | 0.02% | Reduced folding efficiency; cancer-associated |
| c.1789C>T (p.Arg597Trp) | Missense | <0.01% | Dominant-negative effect; neurodegeneration |
Mutation functional classification
Loss of Function (LOF)
Missense mutations (e.g., p.Arg379Cys, p.Glu498Lys) reduce ATPase activity and chaperonin function, leading to protein misfolding and cellular stress.
Gain of Function (GOF)
Not well characterized; overexpression in cancers may confer gain-of-function by enhancing folding of oncoproteins.
Dominant Negative (DN)
p.Arg597Trp disrupts CCT complex integrity, interfering with wild-type subunits and causing dominant-negative effects.
View complete mutation data：
Gene Ontology (GO)
| • ATP binding (GO:0005524) | • chaperonin-containing T-complex (GO:0005832) |
| • protein folding (GO:0006457) | • cellular protein metabolic process (GO:0044267) |
| • tubulin complex assembly (GO:0007021) | • unfolded protein binding (GO:0051082) |
Pathways
• Chaperonin-mediated protein folding (Reactome: R-HSA-390466)
• CCT complex pathway (KEGG: hsa03050)
• Proteasome degradation (interaction with misfolded proteins)
Protein Summary
CCT2 is a 535-amino-acid protein (molecular weight ~57 kDa) that forms the beta subunit of the CCT chaperonin complex. It contains an equatorial ATP-binding domain and an apical substrate-binding domain. CCT2 binds ATP and undergoes conformational changes to encapsulate and fold client proteins such as actin, tubulin, and cell cycle regulators. The protein is highly conserved across eukaryotes and is essential for cell viability.
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