Structurally Divergent Human T Cell Receptor $\gamma $ Proteins Encoded by Distinct C$\gamma $ Genes

The human T cell receptor (TCR) $\gamma $ polypeptide occurs in structurally distinct forms on certain peripheral blood T lymphocytes. Complementary DNA clones representing the transcripts of functionally rearranged TCR $\gamma $ genes in these cells have been analyzed. The expression of a disulfide-linked and a nondisulfide-linked form of TCR $\gamma $ correlated with the use of the C$\gamma $1 and C$\gamma $2 constant-region gene segments, respectively. Variability in TCR $\gamma $ polypeptide size and disulfide linkage is determined by the number of copies and the sequence of a repeated segment of the constant region. Thus, C$\gamma $1 and C$\gamma $2 are used to generate structurally distinct, yet functional, T3-associated receptor complexes on peripheral blood lymphocytes. Tryptic peptide mapping suggests that the T3-associated TCR $\gamma $ and $\delta $ peptides in the nondisulfide-linked form are distinct.