Abstract
Serologic and structural comparisons of the rabbit IgA-g allotypes revealed that 1) the IgA-g allotypes have multiple allotypic determinant sites, 2) the g74, g76 and g77 allotypic specificities have several allotypic determinants in common whereas g75 molecules do not appear to have allotypic determinants in common with g74, g76 and g77 molecules, 3) the partial amino acid sequence of alpha chain from g75 and g76 Fc2alpha fragments differ by at least one amino acid residue, and 4) the g74 alpha-chains may have the "extra" intradomain disulfide bond in the Calpha2 domain whereas the g75 and g76 alpha chains lack this disulfide bond. Thus, multiple mutational events must have occurred during the evolution of g74, g75 and g77 genes.