Beta-2-microglobulin (B2M)
The protein contains 119 amino acids for an estimated molecular weight of 13715 Da.
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). (updated: Oct. 10, 2018)
Protein identification was indicated in the following studies:
- Bryk and co-workers. (2017) Quantitative Analysis of Human Red Blood Cell Proteome. J Proteome Res. 16(8), 2752-2761.
- D'Alessandro and co-workers. (2017) Red blood cell proteomics update: is there more to discover? Blood Transfus. 15(2), 182-187.
Methods
The following articles were analysed to gather the proteome content of erythrocytes.
The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.
| Publication | Identification 1 | Uniprot mapping 2 | Not mapped / Obsolete | TrEMBL | Swiss-Prot |
|---|---|---|---|---|---|
| Goodman (2013) | 2289 (gene list) | 2278 | 53 | 20599 | 2269 |
| Lange (2014) | 1234 | 1234 | 7 | 28 | 1224 |
| Hegedus (2015) | 2638 | 2622 | 0 | 235 | 2387 |
| Wilson (2016) | 1658 | 1528 | 170 | 291 | 1068 |
| d'Alessandro (2017) | 1826 | 1817 | 2 | 0 | 1815 |
| Bryk (2017) | 2090 | 2060 | 10 | 108 | 1942 |
| Chu (2018) | 1853 | 1804 | 55 | 362 | 1387 |
1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry
The compilation of older studies can be retrieved from the Red Blood Cell Collection database.
The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.
This protein is annotated as membranous in Gene Ontology.
Biological Process
Amyloid fibril formation
Antibacterial humoral response
Antigen processing and presentation of endogenous peptide antigen via MHC class I
Antigen processing and presentation of exogenous peptide antigen via MHC class I, TAP-dependent
Antigen processing and presentation of exogenous peptide antigen via MHC class I, TAP-independent
Antigen processing and presentation of exogenous protein antigen via MHC class Ib, TAP-dependent
Antigen processing and presentation of peptide antigen via MHC class I
Antimicrobial humoral immune response mediated by antimicrobial peptide
Cellular protein metabolic process
Cellular response to iron ion
Cellular response to iron(III) ion
Cellular response to lipopolysaccharide
Cellular response to nicotine
Defense response to Gram-negative bacterium
Defense response to Gram-positive bacterium
Innate immune response
Interferon-gamma-mediated signaling pathway
Iron ion homeostasis
Iron ion transport
Learning or memory
Modulation by symbiont of host defense response
Modulation of age-related behavioral decline
Negative regulation of epithelial cell proliferation
Negative regulation of forebrain neuron differentiation
Negative regulation of neurogenesis
Negative regulation of neuron projection development
Negative regulation of receptor binding
Neutrophil degranulation
Positive regulation of cellular senescence
Positive regulation of ferrous iron binding
Positive regulation of protein binding
Positive regulation of receptor binding
Positive regulation of receptor-mediated endocytosis
Positive regulation of T cell cytokine production
Positive regulation of T cell mediated cytotoxicity
Positive regulation of transferrin receptor binding
Protein homotetramerization
Protein refolding
Regulation of defense response to virus by virus
Regulation of erythrocyte differentiation
Regulation of immune response
Regulation of iron ion transport
Regulation of membrane depolarization
Response to cadmium ion
Response to drug
Response to molecule of bacterial origin
Retina homeostasis
T cell differentiation in thymus
Cellular Component
Cytosol
Early endosome lumen
Early endosome membrane
Endoplasmic reticulum lumen
ER to Golgi transport vesicle membrane
External side of plasma membrane
Extracellular exosome
Extracellular region
Extracellular space
Focal adhesion
Golgi apparatus
Golgi membrane
HFE-transferrin receptor complex
Membrane
MHC class I peptide loading complex
MHC class I protein complex
Phagocytic vesicle membrane
Plasma membrane
Recycling endosome membrane
Specific granule lumen
Tertiary granule lumen
The reference OMIM entry for this protein is 105200
Amyloidosis, familial visceral
Amyloidosis viii
Ostertag type amyloidosis
German type amyloidosis
Amyloidosis, familial renal
Amyloidosis, systemic nonneuropathic
A number sign (#) is used with this entry because of the evidence that systemic nonneuropathic amyloidosis is the result of mutation in the apolipoprotein A1 gene (APOA1; 107680), the fibrinogen alpha-chain gene (FGA; 134820), the lysozyme gene (LYZ; 153450), or the gene encoding beta-2-microglobulin (B2M; 109700).
CLINICAL FEATURES
Ostertag (1932, 1950) reported on a family with visceral amyloidosis. A woman, 3 of her children, and 1 of her grandchildren were affected with chronic nephropathy, arterial hypertension, and hepatosplenomegaly. Albuminuria, hematuria and pitting edema were early signs. The age of onset was variable. Death occurred about 10 years after onset. The visceral involvement by amyloid was found to be extensive. Maxwell and Kimbell (1936) described 3 brothers who died of visceral, especially renal, amyloidosis in their 40s. Chronic weakness, edema, proteinuria, and hepatosplenomegaly were features. McKusick (1974) followed up on the family reported by Maxwell and Kimbell (1936). The father of the 3 affected brothers died at age 72 after an automobile accident and their mother died suddenly at age 87 after being in apparent good health. A son of one of the brothers had frequent bouts of unexplained fever in childhood (as did his father and 2 uncles), accompanied at times by nonspecific rash. At the age of 35, proteinuria was discovered and renal amyloidosis was diagnosed by renal biopsy. For 2 years thereafter he displayed the nephrotic syndrome, followed in the next 2 years by uremia from which he died at age 39. Autopsy revealed amyloidosis, most striking in the kidneys but also involving the adrenal glands and spleen. Although some features of the family of Maxwell and Kimbell (1936) are similar to those of urticaria, deafness and amyloidosis (191900), no deafness was present in their family. Weiss and Page (1974) reported a family with 2 definite and 4 probable cases in 3 generations. Mornaghi et al. (1981, 1982) reported rapidly progressive biopsy-proved renal amyloidosis in 3 brothers, aged 49, 52 and 55, of Irish-American origin. None had evidence of a plasma cell dyscrasia, a monoclonal serum or urine protein, or any underlying chronic disease. Immunoperoxidase staining of 1 pulmonary and 1 renal biopsy specimen was negative for amyloid A (AA), amyloid L (AL) and prealbumin. The authors concluded that the disorder in the 3 brothers closely resembled that described by Ostertag (1932). Studying the proband of a kindred with the familial amyloidosis of Ostertag, Lanham et al. (1982) demonstrated permanganate-sensitive congophilia of the amyloid but found no immunofluorescent staining for amyloid A or prealbumin. They concluded that this amyloid may be chemically distinct from previously characterized forms. Libbey and Talbert (1987) described a case of nephropathic amyloidosis, presumably of the Ostertag type. In their case, the amyloid showed no staining for light chains or prealbumin. Involvement of the liver was associated with cholestasis. In the kindred reported by Lanham et al. (1982), 6 members in 2 generations showed the onset of renal disease between ages 23 and 45 years. The deposition of amyloid is characteristically interstitial rather than glomerular as seen in other forms of amyloidosis. The proband had the sicca syndrome. The details of their patient's family history were not given by Libbey and Talbert (1987). Zalin et al. (1991) described yet another family with the Ostertag type of f ... More on the omim web site
June 30, 2020: Protein entry updated
Automatic update: OMIM entry 105200 was added.
Oct. 19, 2018: Additional information
Initial protein addition to the database. This entry was referenced in Bryk and co-workers. (2017).