PSMA4: Proteasome 20S Subunit Alpha 4
Core component of the 20S proteasome complex involved in protein degradation and cellular homeostasis.
Gene Information Card
| Symbol | PSMA4 |
|---|---|
| Full Name | Proteasome 20S Subunit Alpha 4 |
| Gene Type | Protein coding |
| Chromosomal Location | 15q25.1 |
| NCBI Gene ID | 5685 ncbi.nlm.nih.gov/gene/5685 |
| Ensembl ID | ENSG00000137807 |
| UniProt ID | P25789 |
| OMIM ID | 602846 |
| HGNC ID | 9533 |
| Aliases | HC9, PSC9, LMPX, PROS-28.1 |
Description
PSMA4 encodes the alpha 4 subunit of the 20S proteasome core complex. This subunit is essential for proteasome assembly and proteolytic activity, mediating the degradation of ubiquitinated proteins. It plays a critical role in cellular processes such as cell cycle regulation, apoptosis, and antigen presentation.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Prostate cancer | Altered proteasome activity may promote tumor growth | COSMIC; PMID: 25691885 |
| Neurodegenerative disorders (e.g., Alzheimer's) | Impaired proteasomal degradation leads to protein aggregation | UniProt; PMID: 21908915 |
| Autoimmune diseases | Dysregulation of antigen processing via proteasome | NCBI Gene; PMID: 17374725 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Brain | 28.5 | High |
| Heart | 22.1 | Medium |
| Liver | 35.2 | High |
| Kidney | 30.8 | High |
| Lung | 25.0 | Medium |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK 293 | 32.4 | High expression |
| HeLa | 29.7 | High expression |
| K562 | 26.3 | Medium expression |
| HepG2 | 34.1 | High expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.287G>A (p.Arg96His) | Missense | Rare | Unknown functional impact |
| c.523C>T (p.Arg175Trp) | Missense | Rare | Potential loss of function |
| c.1A>G (p.Met1Val) | Start loss | Very rare | Likely loss of function |
Mutation functional classification
Loss of Function (LOF)
Mutations affecting start codon or conserved residues may impair proteasome assembly or activity.
Gain of Function (GOF)
Not reported for PSMA4.
Dominant Negative (DN)
Not reported for PSMA4.
View complete mutation data：
Gene Ontology (GO)
Pathways
• hsa03050: Proteasome
• hsa04120: Ubiquitin mediated proteolysis
• hsa04612: Antigen processing and presentation
Protein Summary
PSMA4 encodes the alpha 4 subunit of the 20S proteasome, a barrel-shaped complex that degrades ubiquitinated proteins. The alpha subunits form the outer rings and regulate substrate entry. PSMA4 is essential for proteasome stability and function, influencing cell cycle, immune response, and protein quality control.
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