The C-terminal sequences of the heavy chains of human immunoglobulin G myeloma proteins of differing isotopes and allotypes

[摘要]

The sequences of the C-terminal octadecapeptides obtained by cyanogen bromide cleavage of the γ-chains of myeloma proteins of the four subclasses, and a urinary heavy-chain-disease protein, have been determined. Although the sequences were markedly homologous, unique replacements were identified that distinguished between the γ_2b, γ_2c and γ_2d subclasses. The data are in accord with the postulated existence of four genetic loci or cistrons, these having arisen by the process of gene duplication.