Structure of HLA antigens: amino-acid and carbohydrate compositions and NH2-terminal sequences of four antigen preparations.

Amino-acid and carbohydrate compositions in addition to limited NH2-terminal sequence data of four preparations of HLA antigens, including products of both of the major histocompatibility loci (HLA-A and HLA-B), show that the antigens have great homology in the primary structure. A striking observation is that HLA antigens also have a considerable structure homology with mouse H-2 antigens. HLA antigens appear to have one carbohydrate side chain which has the same composition in all four cases. The possible relation of the structure of the heavy chain of HLA antigens to immunoglobulins is discussed, based on the limited data which are available so far.