PSMB9: Proteasome 20S Subunit Beta 9
A key immunoproteasome subunit involved in antigen processing and immune regulation
Gene Information Card
| Symbol | PSMB9 |
|---|---|
| Full Name | Proteasome 20S Subunit Beta 9 |
| Gene Type | Protein coding |
| Chromosomal Location | 6p21.32 |
| NCBI Gene ID | 5698 ncbi.nlm.nih.gov/gene/5698 |
| Ensembl ID | ENSG00000240065 |
| UniProt ID | P28065 |
| OMIM ID | 177045 |
| HGNC ID | 9554 |
| Aliases | LMP2, RING12, PSMB6i, beta1i |
Description
PSMB9 (Proteasome 20S Subunit Beta 9) encodes a member of the proteasome B-type family and the immunoproteasome. The protein is a catalytic subunit of the 20S core proteasome complex, specifically replacing the constitutive beta-1 subunit in immunoproteasomes. It is critical for generating peptides for MHC class I antigen presentation, thereby playing a central role in adaptive immunity. The gene is located within the major histocompatibility complex (MHC) class II region on chromosome 6.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Proteasome-associated autoinflammatory syndrome (PRAAS) | Loss-of-function mutations in PSMB9 impair immunoproteasome assembly and activity, leading to dysregulated type I interferon signaling and autoinflammation. | PMID: 25683120; ClinVar |
| Systemic lupus erythematosus (SLE) | PSMB9 polymorphisms are associated with altered antigen processing and increased autoantibody production. | PMID: 22956589; OMIM |
| Cervical cancer | Overexpression of PSMB9 in tumor cells may enhance immune evasion by modulating antigen presentation. | PMID: 31073040; COSMIC |
| Multiple myeloma | PSMB9 mutations contribute to proteasome inhibitor resistance through altered substrate specificity. | PMID: 27548963; COSMIC |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Lymph node | 28.5 | High |
| Spleen | 25.3 | High |
| Bone marrow | 22.1 | High |
| Lung | 12.4 | Medium |
| Liver | 8.7 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK 293 | 15.2 | Embryonic kidney; moderate expression |
| HeLa | 18.9 | Cervical carcinoma; high expression |
| K562 | 22.5 | Leukemia; high expression |
| HepG2 | 10.1 | Hepatocellular carcinoma; medium expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.224G>A (p.Arg75Gln) | Missense | <0.01% | Reduced proteasome activity; associated with PRAAS |
| c.404C>T (p.Thr135Met) | Missense | 0.02% | Altered substrate specificity; reported in multiple myeloma |
| c.1A>G (p.Met1Val) | Start loss | <0.01% | Loss of protein expression; likely pathogenic |
Mutation functional classification
Loss of Function (LOF)
Missense and start-loss mutations impair catalytic activity or protein stability, leading to immunoproteasome deficiency and autoinflammation.
Gain of Function (GOF)
Not well documented; some missense variants may alter substrate preference but not clearly gain-of-function.
Dominant Negative (DN)
Heterozygous mutations in PSMB9 can exert dominant-negative effects by disrupting immunoproteasome assembly.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Immunoproteasome pathway (R-HSA-1236974)
• Antigen processing: Cross-presentation (R-HSA-1236975)
• Proteasome degradation (KEGG hsa03050)
Protein Summary
PSMB9 (UniProt P28065) is a 273-amino-acid protein that forms the beta-1i catalytic subunit of the immunoproteasome. It has a threonine-type endopeptidase activity and is induced by interferon-gamma. The protein is synthesized as a proprotein and cleaved to generate the mature active subunit. It replaces the constitutive beta-1 subunit in immunoproteasomes, altering cleavage specificity to favor production of peptides with hydrophobic C-termini for MHC class I binding.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| PSMB9 Knockout HEK293 Cell Line | EDJ-KQ5575 | Human | 5698 | Details Get a Quote |
| PSMB9 Knockout HCT 116 Cell Line | EDJ-KQ27594 | Human | 5698 | Details Get a Quote |
| PSMB9 Knockout A-549 Cell Line | EDJ-KQ28844 | Human | 5698 | Details Get a Quote |
| PSMB9 Knockout HeLa Cell Line | EDJ-KQ28845 | Human | 5698 | Details Get a Quote |
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