also known as B2M is a component of MHC class I molecules, which are present on all nucleated cells (but not red blood cells). β2
microglobulin lies lateral to the α3
chain on the cell surface. Unlike α3
has no transmembrane region. Directly above β2
lies the α1
chain, which itself is lateral to the α2
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.
The complete amino acid sequence of the beta-2-microglobulin protein. It is a single polypeptide chain with a molecular mass of 11.6 kD that shows homology to immunoglobulins and HLA, suggesting a common evolutionary origin.