T3 glycoprotein is functional although structurally distinct on human T-cell receptor gamma T lymphocytes.

Abstract
The T-cell receptor (TCR) .gamma. gene product occurs in association with T3 (CD3) polypeptides on the surface of human T lymphocytes. TCR .gamma. lymphocytes express arrays of T3 polypeptides distinct from those typically observed on TCR .alpha..beta. lymphocytes. This report demonstrates that identical T3 .gamma., .delta., and .epsilon. polypeptides are synthesized by TCR .gamma. lymphocytes and TCR .alpha..beta. lymphocytes. However, the processing of T3 .delta. oligosaccharides is distinct in the two cell types. This observation may suggest distinct quaternary structures of these receptor complexes. Despite these structural differences, the T3 molecule on TCR .gamma. lymphocytes is functional. It is associated with and comodulates with TCR .gamma. and it serves as a substrate for protein kinase C-mediated phosphorylation. Anti-T3 monoclonal antibodies induce a rapid increase in cytoplasmic free calcium, indicating that the receptor complex is involved in signal transduction and triggering of TCR .gamma. lymphocytes.