Short related sequences in the cytoplasmic domains of CD4 and CD8 mediate binding to the amino-terminal domain of the p56 super(lck) tyrosine protein kinase

We report that the cytoplasmic domains of the T-lymphocyte glycoproteins CD4 and CD8 alpha contain short related amino acid sequences that are involved in binding the amino-terminal domain of the intracellular tyrosine protein kinase, p56 super(lck). Transfer of as few as six amino acid residues from the cytoplasmic domain of the CD8 alpha protein to the cytoplasmic domain of an unrelated protein conferred p56 super(lck) binding to the hybrid protein in HeLa cells. The common sequence motif shared by CD4 and CD8 alpha contains two cysteines, and mutation of either cysteine in the CD4 sequence eliminated binding of p56 super(lck).