B2M

Function

Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system. Exogenously applied M.tuberculosis EsxA or EsxA-EsxB (or EsxA expressed in host) binds B2M and decreases its export to the cell surface (total protein levels do not change), probably leading to defects in class I antigen presentation (PubMed:25356553).

Involvement in disease

Immunodeficiency 43

IMD43

A disorder characterized by marked reduction in serum concentrations of immunoglobulins and albumin, and hypoproteinemia due to hypercatabolism. Patients may suffer from recurrent respiratory tract infections and severe skin disease.

None

The disease is caused by variants affecting the gene represented in this entry.

Amyloidosis, hereditary systemic 6

AMYLD6

A form of hereditary systemic amyloidosis, a disorder characterized by amyloid deposition in multiple tissues resulting in a wide clinical spectrum. AMYLD6 is mainly characterized by gastrointestinal and cardiac symptoms. Neurologic involvement, sicca syndrome, and carpal tunnel syndrome may also be present. Inheritance is autosomal dominant.

None

The disease is caused by variants affecting the gene represented in this entry. Apart from the presence of causative mutations, beta-2-microglobulin may adopt the fibrillar configuration of amyloid, resulting in amyloidosis, when its serum levels are persistently high, as seen in patients on long-term hemodialysis (PubMed:7918443). In contrast to patients with dialysis-related amyloidosis, patients with hereditary amyloidosis have normal circulating concentrations of beta2-microglobulin (PubMed:22693999).

Post-translational modifications

Glycation of Ile-21 is observed in long-term hemodialysis patients.

Sequence Similarities

Belongs to the beta-2-microglobulin family.

Cellular localization

• Secreted
• Cell surface
• Detected in serum and urine (PubMed:1336137, PubMed:7554280).
• (Microbial infection) In the presence of M.tuberculosis EsxA-EsxB complex decreased amounts of B2M are found on the cell surface (PubMed:25356553).

Alternative names

CDABP0092, HDCMA22P, B2M, Beta-2-microglobulin

Database links

swissprot:P61769 entrezGene:2217 swissprot:P55899 omim:601437