Characterization of distinct tyrosine-specific protein kinases in B and T lymphocytes.

摘要: Lymphocyte membrane fractions from both normal and neoplastic sources exhibit tyrosine-specific protein kinase activity. The molecular weights of the endogenous substrates phosphorylated on tyrosine residues differ in B T cells. To further characterize phosphorylation two major classes lymphocytes, tryptic phosphopeptides their were compared sensitivity kinases to inhibition by N alpha-p-tosyl-L-lysine chloromethyl ketone (TLCK) was determined. cell (61,000 55,000 daltons, p61 p55) gel purified after exhaustively digested with trypsin. Separation reverse phase high pressure liquid chromatography demonstrated that these had identical phosphotyrosine containing phosphopeptides. an additional site. Parallel analysis (64,000 58,000 p64 p58) showed they also contained sites identical. However, substrate pairs clearly distinct suggesting arise different gene products. When preincubated TLCK (21 degrees C, 30 min) a dose-dependent decrease p58 resulted. p55 not affected at concentrations up 10 mM TLCK. Tyrosine-specific activity assessed measuring synthetic peptide. plasma inhibited TLCK; unaffected. results suggest some cells have least kinases.