Human major histocompatibility complex (MHC) antigens, also referred to as human leukocyte antigens (HLA), are encoded by genes located on the short arm of chromosome 6 (6p21.3). There are two classes of HLA antigens: class I (HLA-A, B and C) and class II (HLA-D). This class I molecules are polymorphic membrane glycoproteins composed of a heavy (alpha) chain (44 kDa) which is encoded by a HLA class I gene (HLA-A, B or C), and β2-microglobulin light (beta) chain (12 kDa). They are involved in the presentation of foreign antigens to the immune system. (PMID: 667938; 3375250)蛋白别名为:HLA-A HLAA;蛋白质ID:P01891/P01892/P04439/P05534/P10314/P10316/P13746/P16189/P18462/P30443/P30450/P30453/P30455/P30456/P30457/P30512/Q09160