Structural studies on the murine Ia alloantigens. VII. Further evidence for two-gene control of the E/C alloantigens.

By utilizing comparative tryptic peptide analysis of the E/C alloantigens from additional H-2 recombinant strains, the gene encoding the E/C beta subunit was localized to the I-A or B subregions. By peptide mapping techniques, the E/C alpha- and beta-chains showed little structural homology with the A alloantigen alpha and beta subunits. In addition, comparisons of the E/C beta subunits from F1 strains (b x d) with those from both parental strains revealed that in a heterozygote the beta subunit from either allele (b or d) can associate with the alpha-chain from one allele (d). Thus, the formation of hybrid E/C antigens by cis-trans gene complementation increases the E/C alloantigen repertoire in heterozygotes.