PSMG2
Proteasome Assembly Chaperone 2
Gene Information Card
| Symbol | PSMG2 |
|---|---|
| Full Name | Proteasome Assembly Chaperone 2 |
| Gene Type | Protein coding |
| Chromosomal Location | 18p11.21 |
| NCBI Gene ID | 56984 ncbi.nlm.nih.gov/gene/56984 |
| Ensembl ID | ENSG00000101473 |
| UniProt ID | Q969U7 |
| OMIM ID | 609702 |
| HGNC ID | 25096 |
| Aliases | PAC2, PSMG2, HSPC177 |
Description
PSMG2 (Proteasome Assembly Chaperone 2) encodes a chaperone protein involved in the assembly of the 20S proteasome core particle. It binds to the alpha-ring of the proteasome precursor and facilitates proper folding and incorporation of beta subunits, ensuring correct proteasome biogenesis and function.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Proteasome-associated autoinflammatory syndrome (PRAAS) | Loss-of-function mutations impair proteasome assembly, leading to accumulation of ubiquitinated proteins and chronic inflammation | PMID: 26074864 |
| Neurodevelopmental disorder with hypotonia and brain abnormalities | Biallelic PSMG2 variants disrupt proteasome function, affecting neuronal development | PMID: 31585109 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Brain | 12.5 | Medium |
| Heart | 10.3 | Medium |
| Liver | 8.7 | Low |
| Kidney | 9.1 | Low |
| Testis | 15.2 | High |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK293 | 14.8 | High expression |
| HeLa | 11.2 | Medium expression |
| K562 | 9.5 | Low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | Missense | Rare | Loss of start codon, likely loss of function |
| c.214C>T (p.Arg72Trp) | Missense | Rare | Impaired chaperone activity, reduced proteasome assembly |
| c.487_489del (p.Lys163del) | Deletion | Rare | In-frame deletion, disrupts protein stability |
Mutation functional classification
Loss of Function (LOF)
Most PSMG2 mutations result in loss of function, reducing proteasome assembly efficiency and leading to cellular proteotoxic stress.
Gain of Function (GOF)
No gain-of-function mutations reported for PSMG2.
Dominant Negative (DN)
Some missense variants may exert dominant-negative effects by interfering with wild-type chaperone function, though evidence is limited.
View complete mutation data：
Gene Ontology (GO)
| • proteasome complex (GO:0000502) | • ubiquitin-dependent protein catabolic process (GO:0006511) |
| • proteasome assembly (GO:0043248) | • cytosol (GO:0005829) |
| • nucleus (GO:0005634) |
Pathways
• Proteasome assembly (Reactome: R-HSA-9900254)
• Ubiquitin-mediated proteolysis (KEGG: hsa04120)
Protein Summary
PSMG2 (PAC2) is a 27 kDa protein that localizes to the cytosol and nucleus. It forms a heterodimer with PSMG1 (PAC1) to chaperone the assembly of the 20S proteasome alpha-ring. The protein contains a conserved domain that binds to the proteasome precursor, preventing premature beta-subunit incorporation. Defects in PSMG2 lead to impaired proteasome function and are associated with autoinflammatory and neurodevelopmental disorders.
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