Comparison of tyrosine protein kinases in membrane fractions from mouse liver and Ehrlich ascites tumor.

摘要: Tubulin was phosphorylated mainly at tyrosine residues by membranes from mouse liver and Ehrlich ascites tumor with ATP in the presence of MnCl2, ZnCl2, NaVO3, Nonidet P-40 an epidermal growth factor (EGF)- insulin-independent manner. The tubulin kinase activity is comparable to membranes. Two kinases, namely I (Mr = 64,000) II 46,000), were purified 5-17-fold free EGF receptor insulin receptor. Phosphorylation endogenous proteins produced major alkali-resistant phosphoproteins 56 53 kDa preparations 46 37 preparations. These kinases stoichiometrically had a preference alpha-subunit beta-subunit tubulin. Apparent Km values for about 4 8 microM 2 microM, respectively. Thiol reagents inhibited their reactions. N alpha-p-Tosyl-L-lysine chloromethyl ketone stimulated reactions 1 mM but them 5 mM. Although also angiotensin II, tyrosine-glutamate copolymers, heavy chains anti-pp60src IgG, they differed each other preferences substrates. More than 95% enzyme activities not immunoprecipitated IgG which cross-reacts pp60c-src. In comparison corresponding enzymes, enzymes more stable heat incorporated phosphate into tubulin, showed lower toward IgG.