PSMB3: Proteasome 20S Subunit Beta 3
A core component of the proteasome complex involved in protein degradation and cellular homeostasis.
Gene Information Card
| Symbol | PSMB3 |
|---|---|
| Full Name | Proteasome 20S Subunit Beta 3 |
| Gene Type | Protein coding |
| Chromosomal Location | 17q12 |
| NCBI Gene ID | 5691 ncbi.nlm.nih.gov/gene/5691 |
| Ensembl ID | ENSG00000108262 |
| UniProt ID | P49720 |
| OMIM ID | 602176 |
| HGNC ID | 9542 |
| Aliases | HC10-II, LMP10, beta1i, proteasome subunit beta type-3 |
Description
PSMB3 encodes a member of the proteasome B-type family, specifically the beta 3 subunit of the 20S core proteasome complex. This subunit is incorporated into the proteasome and contributes to its chymotrypsin-like, trypsin-like, and peptidyl-glutamyl peptide-hydrolyzing activities. The proteasome is essential for the degradation of ubiquitinated proteins, regulating processes such as cell cycle progression, apoptosis, and antigen presentation.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Proteasome-associated autoinflammatory syndrome (PRAAS) | PSMB3 mutations may impair proteasome assembly or catalytic activity, leading to accumulation of ubiquitinated proteins and chronic inflammation. | ClinVar; PMID: 25620204 |
| Multiple myeloma | Overexpression of PSMB3 has been observed in multiple myeloma, potentially contributing to proteasome hyperactivity and resistance to proteasome inhibitors. | COSMIC; PMID: 23327922 |
| Colorectal cancer | Somatic mutations and altered expression of PSMB3 have been reported in colorectal cancer, possibly affecting protein homeostasis and tumor progression. | COSMIC; PMID: 22810696 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Brain | 15.2 | Medium |
| Liver | 18.7 | Medium |
| Kidney | 22.1 | High |
| Heart | 14.5 | Medium |
| Lung | 16.3 | Medium |
| Spleen | 20.8 | High |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK 293 | 19.5 | Embryonic kidney cells; high expression |
| HeLa | 17.8 | Cervical cancer cells; medium-high expression |
| K562 | 21.3 | Leukemia cells; high expression |
| HepG2 | 18.1 | Liver cancer cells; medium-high 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% | Likely loss of start codon; predicted loss of function |
| c.205C>T (p.Arg69Trp) | Missense | <0.01% | May affect proteasome assembly; reported in PRAAS |
| c.322G>A (p.Gly108Ser) | Missense | <0.01% | Unknown significance; found in cancer samples |
Mutation functional classification
Loss of Function (LOF)
Mutations that disrupt the start codon or critical residues in the beta 3 subunit impair proteasome catalytic activity, leading to accumulation of ubiquitinated proteins.
Gain of Function (GOF)
No confirmed gain-of-function mutations reported for PSMB3.
Dominant Negative (DN)
Some missense mutations may interfere with proteasome assembly or function in a dominant-negative manner, though evidence is limited.
View complete mutation data：
Gene Ontology (GO)
| • endopeptidase activity | • proteasome core complex |
| • proteasome-mediated ubiquitin-dependent protein catabolic process | • threonine-type endopeptidase activity |
| • cytoplasm | • nucleus |
Pathways
• Ubiquitin mediated proteolysis (KEGG: hsa04120)
• Proteasome (KEGG: hsa03050)
• Antigen processing and presentation (KEGG: hsa04612)
Protein Summary
PSMB3 encodes the beta 3 subunit of the 20S proteasome core complex. This subunit is a threonine protease that contributes to the proteolytic activity of the proteasome. The protein is localized in the cytoplasm and nucleus, and is involved in the degradation of ubiquitinated proteins. PSMB3 is expressed in a wide range of tissues, with highest levels in the spleen and kidney. Mutations in PSMB3 are rare but have been associated with proteasome-associated autoinflammatory syndromes and cancer.
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