Tyrosine protein kinase activity of rat spleen and other tissues.

摘要: Using a synthetic peptide (Glu-Asp-Ala-Glu-Tyr-Ala-Ala-Arg-Arg-Arg-Gly) as substrate, various normal tissues from the rat were probed for tyrosine protein kinase activity. Spleen was shown to contain much higher activity than other (lung, brain, testes, liver, kidney, heart, and thymus, in decreasing order of specific activity). Most (greater 80%) present particulate fraction, Nonidet P-40, nonionic detergent, could activate form enzyme 2-20-fold many tissues. Epidermal growth factor (1 microgram/ml), cyclic AMP, GMP, or Ca2+ did not increase spleen Half-maximal observed at 60-80 microM MgATP 2.2 mM peptide, both Mg2+ (10 mM) Mn2+ (0.5-1.0 effective divalent metal ions expression When fraction incubated with [gamma-32P]ATP followed by polyacrylamide gel electrophoresis presence Na dodecyl SO4, number alkali-stable bands identified autoradiography. Two major Mr = 53,000 56,000 phosphotyrosine. similar containing phosphotyrosine but lower amounts 32P labeling also fractions testes). The be solubilized using high concentrations P-40 (5%) an alkaline pH (pH 9.0). Partial purification subsequent filtration on Sephacryl S-200 yielded peak apparent molecular weight 55,000. two phosphorylated co-migrated partially purified preparation only residues when either endogenous proteins casein used substrates. These results suggest that relatively activities exist tissue (rat spleen). Major substrates enzyme(s) appear represented 56,000; one these may itself.