PSMB7: Proteasome 20S Subunit Beta 7
A core component of the proteasome complex involved in protein degradation and cellular homeostasis.
Gene Information Card
| Symbol | PSMB7 |
|---|---|
| Full Name | Proteasome 20S Subunit Beta 7 |
| Gene Type | Protein coding |
| Chromosomal Location | 9q33.3 |
| NCBI Gene ID | 5695 ncbi.nlm.nih.gov/gene/5695 |
| Ensembl ID | ENSG00000136930 |
| UniProt ID | Q99436 |
| OMIM ID | 604030 |
| HGNC ID | 9541 |
| Aliases | LMP7, MECL-1, beta1i, PSMB7i |
Description
PSMB7 encodes a member of the proteasome B-type family, specifically the beta 7 subunit of the 20S core proteasome complex. This subunit is incorporated into the immunoproteasome upon interferon-gamma stimulation, playing a critical role in antigen processing and protein quality control. The gene is located on chromosome 9q33.3 and is essential for proteolytic activity.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Proteasome-associated autoinflammatory syndrome (PRAAS) | Loss-of-function mutations impair proteasome assembly and activity, leading to chronic inflammation and immune dysregulation. | PMID: 25683117 |
| Multiple myeloma | Overexpression of PSMB7 contributes to proteasome hyperactivity, promoting cancer cell survival; targeted by proteasome inhibitors. | PMID: 24141619 |
| Neurodegenerative disorders (e.g., Alzheimer's disease) | Dysregulated proteasome function leads to accumulation of misfolded proteins, with PSMB7 expression altered in affected brain regions. | PMID: 28459452 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Spleen | 28.5 | High |
| Lymph node | 25.3 | High |
| Bone marrow | 22.1 | High |
| Liver | 18.7 | Medium |
| Brain | 12.4 | Medium |
| Heart | 9.8 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK 293 | 35.2 | High expression in embryonic kidney cells |
| K562 | 30.1 | High expression in lymphoblasts |
| HeLa | 27.8 | High expression in cervical cancer cells |
| HepG2 | 20.5 | Moderate expression in liver cancer cells |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.224G>A (p.Arg75Gln) | Missense | Rare | Reduced proteasome activity; associated with PRAAS |
| c.538C>T (p.Arg180Trp) | Missense | Rare | Impaired subunit assembly; linked to autoinflammation |
| c.1A>G (p.Met1Val) | Start loss | Very rare | Loss of protein expression; severe PRAAS phenotype |
Mutation functional classification
Loss of Function (LOF)
Missense and start-loss mutations reduce proteasome catalytic activity and assembly, leading to immune dysregulation.
Gain of Function (GOF)
Not reported; no activating mutations documented in literature.
Dominant Negative (DN)
Heterozygous missense mutations (e.g., p.Arg75Gln) can interfere with wild-type subunit incorporation, exerting dominant-negative effects.
View complete mutation data：
Gene Ontology (GO)
Pathways
• hsa03050 - Proteasome
• hsa04612 - Antigen processing and presentation
• hsa04141 - Protein processing in endoplasmic reticulum
• hsa05022 - Pathways of neurodegeneration - multiple diseases
Protein Summary
PSMB7 encodes the beta 7 subunit of the 20S proteasome, a threonine protease that forms the catalytic core of the proteasome complex. The protein is 277 amino acids long and contains a conserved N-terminal threonine residue essential for proteolytic activity. In the immunoproteasome, PSMB7 replaces the constitutive beta subunit to enhance antigen processing. The protein is highly expressed in immune tissues and is critical for maintaining protein homeostasis.
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