About B2M / Beta 2 Microglobulin:
Beta-2-Microglobulin (also known as β2M) is a Protein Coding gene. Beta 2 microglobulin is found in almost all nucleated cells and most biological fluids, including serum, urine, and synovial fluid, it is a small protein (11,800 Dalton) that's critical for the immune surveillance and modulation in vertebrate animals. Note that currently no genetic variant of β2M is known in humans. It has been speculated that β2M may be directly involved in cancer cell growth, and the β2M level is known to be a prognostic marker for many malignancies.
This gene encodes a serum protein that is present on the surface of nearly all nucleated cells in connection with the major histocompatibility complex (MHC) class I heavy chain. The protein has a mainly beta-pleated sheet structure that, in certain pathological conditions, can form amyloid fibrils. In amniotic fluid, the encoded antimicrobial protein shows antibacterial activity. It has been shown that a mutation in this gene contributes to hypercatabolic hypoproteinemia.
Beta 2 Microglobulin Structure
The human β2M displays a 70% resemblance to the murine protein in the amino acid sequence and both of them are found on the syntonic chromosomes. The secondary β2M structure consists of seven β-strands divided into two β-sheets connected by a single disulphide bridge, presenting a conventional β-sandwich typical of the domain of immunoglobulin (Ig). β2M has no transmembrane region and includes a distinctive molecular structure called a superfamily domain of constant-1 Ig, shared with other adaptive immune molecules, including class I and class II of the major histocompatibility complex (MHC).