Partial Amino Acid Sequences of Chicken and Turkey Immunoglobulin Light Chains. Homology with Mammalian λ Chains

The light chains of normal (heterogeneous) immunoglobulins were isolated from individual chickens and turkeys. A new approach is described for determining the number and approximate ratio of light-chain types present in these species. More than 95% of the chicken and turkey light chains are of a single type that appear to be homologous to mammalian λ chains. On the basis of this homology and the presence of both κ and λ chains in mammals it seems likely that κ and λ chains diverged moee than 250 million years ago-prior to the separation of the mammalian and avian evolutionary lines. Peptide studies and Edman degradations of intact normal light chains indicate in both species that there is a single predominant variable region sequence. About one-third of the chicken light-chain sequence has been determined. The partial sequences of peptides isolated from turkey light chains indicate that they differ from the corresponding peptides in chicken light chains in only 2 of a total of 74 residues.