PSMG1 Proteasome Assembly Chaperone 1
A key chaperone in proteasome assembly and cellular protein homeostasis
Gene Information Card
| Symbol | PSMG1 |
|---|---|
| Full Name | Proteasome Assembly Chaperone 1 |
| Gene Type | Protein coding |
| Chromosomal Location | 21q22.3 |
| NCBI Gene ID | 8624 ncbi.nlm.nih.gov/gene/8624 |
| Ensembl ID | ENSG00000160200 |
| UniProt ID | O95456 |
| OMIM ID | 605296 |
| HGNC ID | 9573 |
| Aliases | PAC1, PSMG1, proteasome (prosome, macropain) assembly chaperone 1 |
Description
PSMG1 encodes proteasome assembly chaperone 1 (PAC1), which forms a heterodimer with PAC2 (PSMG2) to facilitate the assembly of the 20S core particle of the proteasome. It prevents premature proteolytic activation and ensures proper incorporation of alpha and beta subunits. PSMG1 is essential for maintaining cellular protein homeostasis and is implicated in cancer and neurodegenerative disorders.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Prostate cancer | Altered PSMG1 expression may affect proteasome activity and tumor progression | PMID: 25686104 |
| Breast cancer | PSMG1 overexpression correlates with poor prognosis and proteasome dysregulation | PMID: 29187737 |
| Alzheimer's disease | Impaired proteasome assembly due to PSMG1 dysfunction may contribute to tau and amyloid pathology | PMID: 25452315 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 12.5 | Medium |
| Brain | 8.3 | Medium |
| Liver | 6.1 | Low |
| Heart | 5.4 | Low |
| Kidney | 7.2 | Medium |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK293 | 14.2 | High expression |
| HeLa | 11.8 | High expression |
| K562 | 9.5 | Medium expression |
| MCF7 | 8.1 | Medium expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | Missense | <0.01% | Loss of start codon, likely loss of function |
| c.287C>T (p.Thr96Ile) | Missense | <0.01% | Unknown functional effect |
| c.424G>A (p.Glu142Lys) | Missense | <0.01% | Unknown functional effect |
Mutation functional classification
Loss of Function (LOF)
Loss-of-function mutations in PSMG1 are rare but may impair proteasome assembly, leading to proteotoxic stress.
Gain of Function (GOF)
No confirmed gain-of-function mutations reported.
Dominant Negative (DN)
No dominant-negative mutations described.
View complete mutation data：
Gene Ontology (GO)
| • proteasome assembly | • chaperone activity |
| • protein folding | • protein homodimerization activity |
| • cytoplasm |
Pathways
• Proteasome assembly (Reactome: R-HSA-99015)
• Ubiquitin-mediated proteolysis (KEGG: hsa04120)
Protein Summary
PSMG1 (PAC1) is a 29 kDa chaperone that forms a heterodimer with PAC2 to orchestrate the ordered assembly of the 20S proteasome core particle. It binds to alpha subunits to prevent premature beta subunit incorporation and proteolytic activation. PSMG1 is widely expressed, with highest levels in testis and brain. Dysregulation is linked to cancer and neurodegeneration.
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|---|---|---|---|---|
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