B2M (Beta-2-Microglobulin) Gene
Essential component of MHC class I molecules and biomarker in immune function and disease
Gene Information Card
| Symbol | B2M |
|---|---|
| Full Name | Beta-2-Microglobulin |
| Gene Type | Protein coding |
| Chromosomal Location | 15q21.1 |
| NCBI Gene ID | 567 ncbi.nlm.nih.gov/gene/567 |
| Ensembl ID | ENSG00000166710 |
| UniProt ID | P61769 |
| OMIM ID | 109700 |
| HGNC ID | 914 |
| Aliases | HDCMA22P, IMD43 |
Description
The B2M gene encodes beta-2-microglobulin, a 12 kDa protein that forms the light chain of major histocompatibility complex (MHC) class I molecules. It is essential for proper MHC class I assembly, stability, and cell surface expression, enabling antigen presentation to CD8+ T cells. B2M is also involved in immune surveillance and is a clinical biomarker for renal function, dialysis-related amyloidosis, and certain cancers.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Immunodeficiency 43 (IMD43) | Loss-of-function mutations in B2M impair MHC class I expression, leading to defective CD8+ T cell responses and recurrent infections. | ClinVar, OMIM |
| Dialysis-related amyloidosis | Accumulation of beta-2-microglobulin amyloid fibrils in joints and soft tissues due to impaired renal clearance. | OMIM, NCBI |
| Colorectal cancer | B2M mutations or loss of heterozygosity cause MHC class I downregulation, enabling immune evasion. | COSMIC, NCBI |
| Multiple myeloma | Elevated serum beta-2-microglobulin is a prognostic marker for disease progression and survival. | NCBI, ClinVar |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Lymph node | 78.5 | High |
| Spleen | 72.3 | High |
| Bone marrow | 65.1 | High |
| Blood | 58.9 | High |
| Lung | 42.7 | Medium |
| Kidney | 38.4 | Medium |
| Liver | 25.6 | Medium |
| Brain | 8.2 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| K-562 (leukemia) | 89.4 | High expression |
| HeLa (cervical) | 76.2 | High expression |
| A549 (lung) | 55.3 | Medium expression |
| HepG2 (liver) | 32.1 | Medium expression |
| SH-SY5Y (neuronal) | 12.8 | Low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.67C>T (p.Arg23*) | Nonsense | Rare | Loss of function; truncated protein; associated with IMD43 |
| c.238G>A (p.Gly80Ser) | Missense | Rare | Impaired MHC class I assembly; reduced cell surface expression |
| c.1A>G (p.Met1?) | Start loss | Rare | Loss of translation initiation; complete loss of function |
| c.316_317del (p.Leu106fs) | Frameshift | Rare | Premature stop; loss of function |
Mutation functional classification
Loss of Function (LOF)
Most B2M mutations are loss-of-function, leading to reduced or absent MHC class I expression and impaired antigen presentation.
Gain of Function (GOF)
No gain-of-function mutations are reported for B2M.
Dominant Negative (DN)
No dominant-negative effects are documented; B2M mutations are typically recessive.
View complete mutation data：
Gene Ontology (GO)
| • GO:0002250 – adaptive immune response | • GO:0002474 – antigen processing and presentation of exogenous peptide antigen via MHC class I |
| • GO:0002486 – antigen processing and presentation of endogenous peptide antigen via MHC class I | • GO:0005515 – protein binding |
| • GO:0030881 – beta-2-microglobulin binding | • GO:0042605 – peptide antigen binding |
Pathways
• Antigen processing and presentation (KEGG hsa04612)
• Class I MHC mediated antigen processing and presentation (Reactome R-HSA-983169)
• Immunoregulatory interactions between a Lymphoid and a non-Lymphoid cell (Reactome R-HSA-198933)
Protein Summary
Beta-2-microglobulin (B2M) is a 119-amino acid protein with a single immunoglobulin-like domain. It non-covalently associates with the alpha chain of MHC class I molecules, forming the complete heterotrimer required for peptide presentation. B2M is synthesized in all nucleated cells and is secreted into serum, where its levels reflect cell turnover and renal function. Structurally, it consists of a beta-sandwich fold typical of immunoglobulin domains. Mutations or deficiency lead to immunodeficiency, while overexpression or aggregation contributes to amyloidosis and cancer progression.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| B2M Knockout A-549 Cell Line | EDC07863 | Human | 567 | Details Get a Quote |
| B2M Knockout HEK293T Cell Line | EDC07693 | Human | 567 | Details Get a Quote |
| B2M Knockout Hep-G2 Cell Line | EDJ-KQ38 | Human | 567 | Details Get a Quote |
| B2M Knockout C2C12 Cell Line | EDJ-KQ82 | Mouse | 12010 | Details Get a Quote |
| B2M Knockout K-562 Cell Line | EDJ-KQ85 | Human | 567 | Details Get a Quote |
| B2M Knockout SNU-449 Cell Line | EDJ-KQ89 | Human | 567 | Details Get a Quote |
| B2M Knockout THP-1 Cell Line | EDJ-KQ91 | Human | 567 | Details Get a Quote |
| TFB2M Knockout HEK293 Cell Line | EDJ-KQ12009 | Human | 64216 | Details Get a Quote |
| B2M Knockout HEK293 Cell Line | EDJ-KQ12503 | Human | 567 | Details Get a Quote |
| B2M Knockout HCT 116 Cell Line | EDJ-KQ41482 | Human | 567 | Details Get a Quote |
| B2M Knockout HeLa Cell Line | EDJ-KQ41483 | Human | 567 | Details Get a Quote |
| B2M Knockout A-375 Cell Line | EDC07626 | Human | 567 | Details Get a Quote |
| TFB2M Knockout HCT 116 Cell Line | EDJ-KQ40595 | Human | 64216 | Details Get a Quote |
| TFB2M Knockout HeLa Cell Line | EDJ-KQ40596 | Human | 64216 | Details Get a Quote |
| B2M Knockout MC-38 Cell Line | EDJ-KZ113 | Mouse | 567 | Details Get a Quote |
Displaying Records 1 To 15 Of 17 Records
