Evolution of Immunoglobulin Polypeptide Chains: Carboxy-Terminal of an IgM Heavy Chain

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Science  23 Dec 1966:
Vol. 154, Issue 3756, pp. 1561-1562
DOI: 10.1126/science.154.3756.1561


The dipeptide sequence at the carboxy-terminal of a heavy (µ) chain from a human macroglobulin ( IgM) is tyrosylcysteine, although the reverse sequence, cysteinyltyrosine, has not been rigorously excluded. The presence of cysteine at the carboxy-terminal was predicted from a recognition of the chemical homologies among the polypeptide chains of immunoglobulins, and their probable evolutionary origin.