Isolation of cDNA clones encoding the 20K T3 glycoprotein of human T-cell receptor complex.

The complete amino acid sequence of one of the polypeptide chains of the human T3/T-cell receptor complex, the T3 glycoprotein (T3-delta-chain) of relative molecular mass 20,000, was deduced from cDNA clones derived from HPB-ALL cells and a human T-cell clone. Inspection of the 171-amino acid sequence reveals a signal peptide, a 79-amino acid extracellular domain, one transmembrane region and a 44-amino acid intracellular domain which show no sequence homology with members of the T-cell receptor/immunoglobulin/MHC multi-gene family. The T3 delta-chain is coded for by a single-copy gene the expression of which is restricted to T lymphocytes in humans and mice.