MOLECULAR DETERMINANTS OF A11 AND A12 ALLOTYPIC SPECIFICITIES IN RABBIT IMMUNOGLOBULIN

The finding that group a allotypes, segregating genetic markers determined by primary structure of the Fd region, are present on the distinctive heavy chains of several classes of rabbit immunoglobulin has posed a problem in understanding the nature of the genetic control of immunoglobulin synthesis. Recently a new system of allotypic markers, A11 and A12, detected by hemagglutination techniques has been identified on the γ heavy chain of rabbit immunoglobulin G. In the present paper it is shown that A11 correlated with methionine on the N-terminal side of the half-cystine participating in the inter-γ-chain bond, whereas A12 correlates with threonine at this position. The significance of the methionine-threonine interchange sharing the same chain with amino acid sequences determining the group a allotypes is considered in relationship to the genetic control of the biosynthesis of heavy and light chains of immunoglobulin. © 1969, American Chemical Society. All rights reserved.