Engelsk definition
An 11-kDa protein associated with the outer membrane of many cells including LYMPHOCYTES. It is the small subunit of MHC CLASS I MOLECULES. Association with beta 2-microglobulin is generally required for the transport of class I heavy chains from the endoplasmic reticulum to the cell surface. Beta 2-microglobulin is present in small amounts in serum, CEREBROSPINAL FLUID, and urine of healthy individuals, and to a much greater degree in the urine and plasma of patients with tubular PROTEINURIA, renal failure, or kidney transplants.