A human T cell‐specific cDNA clone (YT16) encodes a protein with extensive homology to a family of protein‐tyrosine kinases

We report here the isolation of a human T cell‐specific cDNA clone (YT16) that encodes a protein with extensive homology to a family of transformation and proliferation‐related protein‐tyrosine kinases (PTK). The message size of YT16 is 2.2 kb and it encodes a protein of 507 amino acids with a mol. mass of 57136 Daltons. The deduced protein sequence has an overall homology of about 50% to the viral oncogene products of src and yes. Around the PTK catalytic domain, the homologies increase to 70–80% between the deduced protein sequence of YT16 and those of the PTK viral oncogenes. Of special interest is the extensive homology between the deduced protein sequence of YT16 and that of a recently reported murine B and T lymphocyte‐specific PTK, lsk^T. It is possible that YT16 either encodes the human homologue of this murine gene, or a protein with similar function(s) in T cells.