Specific Expression of a Tyrosine Kinase Gene, blk , in B Lymphoid Cells

• DOI: 10.1126/science.2404338
• Publication Date: 2006-10-05T22:10:14Z
• Authors: Susan M. Dymecki; John E. Niederhuber; Stephen V. Desiderio
• Keywords: B-Lymphocytes; 0303 health sciences; Base Sequence; Molecular Sequence Data; Gene Expression; DNA; Protein-Tyrosine Kinases; 3. Good health; Mice; 03 medical and health sciences; src-Family Kinases; Escherichia coli; Animals; Amino Acid Sequence; Codon; Signal Transduction

Several pathways of transmembrane signaling in lymphocytes involve protein-tyrosine phosphorylation. With the exception of p56

lck

, a tyrosine kinase specific to T lymphoid cells that associates with the T cell transmembrane proteins CD4 and CD8, the kinases that function in these pathways are unknown. A murine lymphocyte complementary DNA that represents a new member of the src family has now been isolated and characterized. This complementary DNA, termed blk (for B lymphoid kinase), specifies a polypeptide of 55 kilodaltons that is related to, but distinct from, previously identified retroviral or cellular tyrosine kinases. The protein encoded by blk exhibits tyrosine kinase activity when expressed in bacterial cells. In the mouse and among cell lines, blk is specifically expressed in the B cell lineage. The tyrosine kinase encoded by blk may function in a signal transduction pathway that is restricted to B lymphoid cells.