PSMB11: Proteasome 20S Subunit Beta 11
A specialized proteasome subunit essential for thymoproteasome assembly and positive selection of CD8+ T cells
Gene Information Card
| Symbol | PSMB11 |
|---|---|
| Full Name | Proteasome 20S Subunit Beta 11 |
| Gene Type | Protein coding |
| Chromosomal Location | 14q11.2 |
| NCBI Gene ID | 122706 ncbi.nlm.nih.gov/gene/122706 |
| Ensembl ID | ENSG00000100811 |
| UniProt ID | Q5JRA6 |
| OMIM ID | 610020 |
| HGNC ID | 17763 |
| Aliases | beta5t, MECL-2, proteasome subunit beta type-11 |
Description
PSMB11 encodes the beta-5t subunit of the 20S proteasome, a specialized catalytic subunit exclusively incorporated into the thymoproteasome. The thymoproteasome is expressed in cortical thymic epithelial cells (cTECs) and is critical for generating the MHC class I peptide repertoire required for positive selection of CD8+ T cells. Unlike the constitutive beta5 subunit, beta5t has reduced chymotrypsin-like activity, which shapes the peptide pool for optimal T cell development.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Immunodeficiency (CD8+ T cell deficiency) | Loss of PSMB11 impairs thymoproteasome function, reducing MHC class I peptide presentation and CD8+ T cell positive selection | Mouse models: Psmb11 knockout mice show severe CD8+ T cell lymphopenia (PMID: 17463289) |
| Autoimmune disorders | Altered thymoproteasome activity may affect T cell repertoire selection, predisposing to autoimmunity | Association studies in human cohorts (PMID: 25605274) |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Thymus | 12.5 | High |
| Spleen | 0.2 | Low |
| Lymph node | 0.1 | Low |
| Bone marrow | 0.1 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| Cortical thymic epithelial cells (cTECs) | High | Primary cell type expressing PSMB11 |
| Thymic fibroblasts | Low | Minor expression |
| HEK293 | 0.0 | No endogenous expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | Missense | Rare | Loss of start codon, likely loss of function |
| c.224C>T (p.Thr75Ile) | Missense | <0.01% | Reduced proteasome activity in vitro |
Mutation functional classification
Loss of Function (LOF)
Mutations that disrupt beta5t incorporation into the proteasome or catalytic activity lead to impaired thymoproteasome function and CD8+ T cell deficiency.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
No dominant-negative mutations reported.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Proteasome degradation (KEGG hsa03050)
• Antigen processing and presentation (KEGG hsa04612)
• Thymoproteasome assembly (Reactome R-HSA-1236974)
Protein Summary
PSMB11 encodes beta5t, a 276-amino acid catalytic subunit of the 20S proteasome. It replaces the constitutive beta5 subunit specifically in thymoproteasomes expressed in cortical thymic epithelial cells. Beta5t has a unique active site that reduces chymotrypsin-like cleavage, generating peptides with lower affinity for MHC class I molecules, which is essential for positive selection of CD8+ T cells. The protein is localized to the nucleus and cytoplasm.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| PSMB11 Knockout HEK293 Cell Line | EDJ-KQ8161 | Human | 122706 | Details Get a Quote |
| PSMB11 Knockout HeLa Cell Line | EDJ-KQ58105 | Human | 122706 | Details Get a Quote |
| PSMB11 Knockout A-549 Cell Line | EDJ-KQ66593 | Human | 122706 | Details Get a Quote |
| PSMB11 Knockout HCT 116 Cell Line | EDJ-KQ75009 | Human | 122706 | Details Get a Quote |
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