Beta-2 microglobulin

Beta-2-microglobulin
PDB rendering based on 1a1m.
Available structures: 1a1m, 1a1n, 1a1o, 1a6z, 1a9b, 1a9e, 1agb, 1agc, 1agd, 1age, 1agf, 1akj, 1ao7, 1b0g, 1b0r, 1bd2, 1c16, 1ce6, 1cg9, 1de4, 1duy, 1duz, 1e27, 1e28, 1eey, 1eez, 1efx, 1exu, 1gzp, 1gzq, 1hhg, 1hhh, 1hhi, 1hhj, 1hhk, 1hla, 1hsa, 1hsb, 1i1f, 1i1y, 1i4f, 1i7r, 1i7t, 1i7u, 1im3, 1im9, 1jf1, 1jgd, 1jge, 1jht, 1jnj, 1k5n, 1kpr, 1ktl, 1lds, 1lp9, 1m05, 1m6o, 1mhe, 1mi5, 1n2r, 1of2, 1oga, 1ogt, 1onq, 1p7q, 1py4, 1q94, 1qew, 1qlf, 1qqd, 1qr1, 1qrn, 1qse, 1qsf, 1qvo, 1r3h, 1s8d, 1s9w, 1s9x, 1s9y, 1sys, 1syv, 1t1w, 1t1x, 1t1y, 1t1z, 1t20, 1t21, 1t22, 1tmc, 1tvb, 1tvh, 1uqs, 1uxs, 1uxw, 1vgk, 1w0v, 1w0w, 1w72, 1x7q, 1xh3, 1xr8, 1xr9, 1xz0, 1ydp, 1ypz, 1zhk, 1zhl, 1zs8, 1zsd, 1zt4, 1zvs, 2a83, 2ak4, 2av1, 2av7, 2axf, 2axg, 2bck, 2bnq, 2bnr, 2bsr, 2bss, 2bst, 2bsu, 2bsv, 2bvo, 2bvp, 2bvq, 2c7u, 2cii, 2cik, 2clr, 2d31, 2d4d, 2d4f, 2dyp, 2esv, 2f53, 2f54, 2f74, 2f8o, 2fyy, 2fz3, 2git, 2gj6, 2h26, 2h6p, 2hjk, 2hjl, 2hla, 2hn7, 2nw3, 2nx5, 3hla
Identifiers
Symbol(s)	B2M;
External IDs	OMIM: 109700 MGI: 88127 Homologene: 2987
Gene Ontology Molecular Function: • protein binding Cellular Component: • extracellular region • MHC class I protein complex Biological Process: • antigen processing and presentation of peptide antigen via MHC class I • immune response
RNA expression pattern
Additional recommended knowledge Essential Laboratory Skills Guide Safe Weighing Range Ensures Accurate Results Don't let static charges disrupt your weighing accuracy More reference expression data
Orthologs
	Human	Mouse
Entrez	567	12010
Ensembl	ENSG00000166710	ENSMUSG00000060802
Uniprot	P61769	Q3U679
Refseq	NM_004048 (mRNA) NP_004039 (protein)	NM_009735 (mRNA) NP_033865 (protein)
Location	Chr 15: 42.79 - 42.8 Mb	Chr 2: 121.84 - 121.84 Mb
Pubmed search	[1]	[2]

β₂ microglobulin is a component of MHC class I molecules, which are present on almost all cells of the body (red blood cells are a notable exception). β₂ microglobulin lies lateral to the α₃ chain on the cell surface. Unlike α₃, β₂ has no transmembrane region. Directly above β₂ (i.e. away from the cell) lies the α₁ chain, which itself is lateral to the α₂. β₂ microglobulin associates not only with the alpha chain of MHC class I molecules, but also with class I-like molecules such as CD1 and Qa.

In patients on long-term hemodialysis, it can aggregate into amyloid fibers that deposit in joint spaces, a disease known as dialysis-related amyloidosis.

Mice models deficient for the β₂ microglobulin gene have been engineered. These mice demonstrate that β₂ microglobulin is necessary for cell surface expression of MHC class I and stability of the peptide binding groove. In fact, in the absence of β₂ microglobulin, very limited amounts of MHC class I (classical and non-classical) molecules can be detected on the surface. In the absence of MHC class I, CD8 T cells cannot develop. CD8 T cells are a subset of T cells involved in the development of acquired immunity.

Further reading