Ia antigens: isolation, chemical modification and structural characterization.

The results described above, with respect to the similarity of basic structural features of Ia and H-2 antigens (see Table V), led to the evolutionary concept presented in Figure 10 according to which these antigens are the products of tandem-duplicated genes. The evolution of MHC-gene products is reflected by the basic structure of these molecules. This structure is compatible with basic repetitive units of molecular weight 12,000 as suggested by the selective cleavage of the intact protein by, for example, papain.