beta 2-Microglobulin

**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.

**Tree numbers:** - D09.400.430.890.489.100 - D12.776.124.790.223.100 - D12.776.377.715.182.100 - D12.776.395.550.489.100 - D12.776.543.550.439.100 - D23.050.301.500.100.175 - D23.050.705.552.100.175

**Synonyms:** - Thymotaxin