Biochemical characterization of an invariant polypeptide associated with Ia antigens in human and mouse.
Ii, a 31,000 mol. wt polypeptide chain associated with murine and human Ia antigens was investigated for its labeling pattern, carbohydrate content and structural polymorphism. Two-dimensional gel electrophoretic analysis of tunicamycin treated cells from mouse and human lymphocytes shows that Ii contains two N-linked carbohydrate chains. Ii is a methionine rich polypeptide. Tryptic and chymotryptic two dimensional peptide maps of Ii chain associated with I-A and I-E subregion products are identical. This absence of polymorphism holds true when Ii chain is isolated from different mouse haplotypes. Human Ii chains from different HLA-DR types appear also invariant by peptide map analysis. By molecular weight, carbohydrate content, charge and tryptic and chymotryptic maps criteria, Ii of mouse and human are strikingly homologous.
D000818:Animals; D002241:Carbohydrates / Q000032:analysis; D055598:Chemical Phenomena; D002621:Chemistry; D002918:Chymotrypsin; D004591:Electrophoresis, Polyacrylamide Gel; D000949:Histocompatibility Antigens Class II; D006801:Humans; D007123:Immunoelectrophoresis, Two-Dimensional; D051379:Mice; D010455:Peptides; D011110:Polymorphism, Genetic; D014357:Trypsin
D002241:Carbohydrates; D000949:Histocompatibility Antigens Class II; D010455:Peptides; D002918:Chymotrypsin; D014357:Trypsin