Isolation and characterization of mouse beta 2-microglobulin allotypes

Two allelic forms of mouse beta 2-microglobulin (beta 2m), the smaller polypeptide chain of the H-2 histocompatibility antigens, were purified from urine and partially characterized. The isoelectric points of the two allotypes are 7.4 (beta 2ma) and 8.1 (beta 2mb). The electrophoretic mobility of beta 2ma is decreased by reduction, whereas the mobility of beta 2mb is not. Urinary beta 2m can replace endogenous beta 2m in mouse H-2 histocompatibility antigens.