Unusual features of the T-cell receptor C domains are revealed by structural comparisons with other members of the immunoglobulin superfamily.

The amino acid sequences of the domains of human, mouse and rabbit T-cell antigen receptors have been aligned with those of immunoglobulin domains of known three-dimensional structure. Computerized secondary structure predictions have been performed on the sequences and putative models of the domains have been constructed. The receptor V alpha and V beta domains are closely related to immunoglobulin VH domains. The receptor C alpha domain shows some major divergences from immunoglobulin C domains and the C beta domain displays an unusual feature. The implications for T-cell receptor function are discussed.