PSMA2: Proteasome 20S Subunit Alpha 2
A core component of the 20S proteasome complex involved in protein degradation and cellular homeostasis.
Gene Information Card
| Symbol | PSMA2 |
|---|---|
| Full Name | Proteasome 20S Subunit Alpha 2 |
| Gene Type | protein-coding |
| Chromosomal Location | 7p13 |
| NCBI Gene ID | 5683 ncbi.nlm.nih.gov/gene/5683 |
| Ensembl ID | ENSG00000106588 |
| UniProt ID | P25787 |
| OMIM ID | 176843 |
| HGNC ID | 9534 |
| Aliases | HC3, PSC2, PROS-30, proteasome subunit alpha type-2 |
Description
PSMA2 encodes the alpha 2 subunit of the 20S proteasome core complex. This subunit is essential for proteolytic degradation of ubiquitinated proteins, regulating cell cycle, apoptosis, and antigen processing. The gene is located on chromosome 7p13 and is widely expressed across tissues.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Prostate cancer | PSMA2 overexpression may enhance proteasome activity, promoting tumor cell survival and resistance to apoptosis. | PMID: 25605247 |
| Multiple myeloma | Proteasome subunit dysregulation, including PSMA2, contributes to resistance to bortezomib therapy. | PMID: 22101928 |
| Neurodegenerative disorders (e.g., Alzheimer's) | Impaired proteasome function due to altered PSMA2 expression may lead to accumulation of misfolded proteins. | PMID: 17925230 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 48.2 | High |
| Brain (cerebellum) | 35.7 | High |
| Liver | 28.1 | Medium |
| Heart | 22.5 | Medium |
| Lung | 18.9 | Medium |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK 293 | 42.3 | High expression in embryonic kidney cells |
| HeLa | 38.7 | High expression in cervical cancer cells |
| K562 | 30.1 | Medium expression in leukemia cells |
| HepG2 | 25.6 | Medium expression in liver cancer cells |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | missense | <0.01% | Potential loss of start codon, likely loss of function |
| c.337C>T (p.Arg113Trp) | missense | <0.01% | Unknown functional effect; rare population variant |
| c.568G>A (p.Glu190Lys) | missense | <0.01% | Predicted possibly damaging by in silico tools |
Mutation functional classification
Loss of Function (LOF)
No confirmed loss-of-function mutations reported in large cohorts; start codon variant may lead to null allele.
Gain of Function (GOF)
No known gain-of-function mutations.
Dominant Negative (DN)
Not described for PSMA2.
View complete mutation data：
Gene Ontology (GO)
| • endopeptidase activity | • proteasome core complex |
| • protein ubiquitination | • proteolysis involved in cellular protein catabolic process |
| • antigen processing and presentation of exogenous peptide antigen via MHC class I |
Pathways
• Ubiquitin-mediated proteolysis (KEGG: hsa04120)
• Proteasome (KEGG: hsa03050)
• Antigen processing and presentation (KEGG: hsa04612)
Protein Summary
PSMA2 encodes the alpha 2 subunit (also known as HC3) of the 20S proteasome. This subunit forms part of the outer alpha ring of the proteasome core particle, which gates substrate entry. The protein is highly conserved and expressed in all eukaryotic cells. It plays a critical role in maintaining protein homeostasis by degrading ubiquitin-tagged proteins. Dysregulation of PSMA2 has been implicated in cancer and neurodegenerative diseases.
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