PSMB4: Proteasome 20S Subunit Beta 4
A core component of the proteasome complex involved in protein degradation and implicated in cancer and immune disorders.
Gene Information Card
| Symbol | PSMB4 |
|---|---|
| Full Name | Proteasome 20S Subunit Beta 4 |
| Gene Type | Protein coding |
| Chromosomal Location | 1q21.3 |
| NCBI Gene ID | 5692 ncbi.nlm.nih.gov/gene/5692 |
| Ensembl ID | ENSG00000142507 |
| UniProt ID | P28070 |
| OMIM ID | 602175 |
| HGNC ID | 9540 |
| Aliases | HN3, PROS-26, HsN3, beta2, LMPX |
Description
PSMB4 encodes a member of the proteasome B-type family and the 20S proteasome core subunit beta-4. This subunit is essential for proteolytic activity of the proteasome, which degrades ubiquitinated proteins. PSMB4 is also a component of the immunoproteasome when replaced by beta-1i (PSMB9) and beta-2i (PSMB10) under interferon-gamma stimulation. Altered expression and mutations are linked to multiple cancers and autoimmune conditions.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Multiple Myeloma | Overexpression of PSMB4 contributes to proteasome hyperactivity, promoting cell survival and resistance to apoptosis. | PMID: 25964205; COSMIC |
| Breast Cancer | PSMB4 upregulation correlates with poor prognosis and increased proliferation via NF-kB pathway activation. | PMID: 29351280; NCBI Gene |
| Hepatocellular Carcinoma | PSMB4 overexpression enhances proteasome activity, leading to degradation of tumor suppressors. | PMID: 31065034; COSMIC |
| Proteasome-associated autoinflammatory syndrome (PRAAS) | Loss-of-function mutations in PSMB4 impair proteasome assembly, causing immune dysregulation. | OMIM #602175; ClinVar |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 18.5 | High |
| Kidney | 15.2 | High |
| Heart | 12.8 | Medium |
| Brain | 8.3 | Medium |
| Lung | 10.1 | Medium |
| Skeletal Muscle | 6.7 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK 293 | 22.4 | High expression in embryonic kidney cells |
| HeLa | 19.8 | High expression in cervical cancer cells |
| K562 | 14.5 | Moderate expression in leukemia cells |
| HepG2 | 17.3 | High expression in liver cancer cells |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.214A>G (p.Thr72Ala) | Missense | <0.01% | Unknown; reported in ClinVar as VUS |
| c.1A>G (p.Met1Val) | Start loss | <0.01% | Likely loss of function; associated with PRAAS |
| c.404_405del (p.Glu135Glyfs*2) | Frameshift | <0.01% | Loss of function; reported in COSMIC |
Mutation functional classification
Loss of Function (LOF)
Frameshift and start-loss mutations impair proteasome assembly and catalytic activity, leading to immune dysregulation (PRAAS).
Gain of Function (GOF)
Not well documented; overexpression in cancers suggests possible gain-of-function via increased proteolysis.
Dominant Negative (DN)
Not reported for PSMB4.
View complete mutation data：
Gene Ontology (GO)
Pathways
• hsa03050 - Proteasome (KEGG)
• R-HSA-983168 - Antigen processing: Ubiquitination & Proteasome degradation (Reactome)
• R-HSA-1234176 - Regulation of proteasomal degradation (Reactome)
Protein Summary
PSMB4 encodes the beta-4 subunit of the 20S proteasome core. This subunit is a threonine protease that cleaves peptide bonds in the proteolytic chamber. It is constitutively expressed and can be replaced by inducible subunits to form the immunoproteasome. The protein is 264 amino acids long with a molecular weight of ~29 kDa. It is essential for cellular protein homeostasis and antigen presentation.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| PSMB4 (NC_000001.11:g.151399383G>C) Point Mutation in A-549 Cell Line | EDC03002 | Human | 5692 | Details Get a Quote |
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