pp54 microtubule-associated protein 2 kinase. A novel serine/threonine protein kinase regulated by phosphorylation and stimulated by poly-L-lysine.
pp54 microtubule-associated protein 2 kinase. A novel serine/threonine protein kinase regulated by phosphorylation and stimulated by poly-L-lysine.
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DOI：
10.1016/s0021-9258(17)44910-6
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发表时间：
1990-10
期刊：
影响因子：
--
通讯作者：
J. Kyriakis;J. Avruch
中科院分区：
文献类型：
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作者：
J. Kyriakis;J. Avruch
在大鼠体内注射放线菌胺后，一种使Ser/Thr残基上的微管相关蛋白2(MAP-2)磷酸化的蛋白激酶被显著激活。该酶已经纯化了10,000倍以上，接近均一，相当于一个54 kDa的多肽，基于自动磷酸化，十二烷基硫酸钠凝胶活性的复性，以及凝胶过滤。蛋白激酶活性不受预先的自磷酸化、钙离子、二酰甘油和磷脂、环核苷酸、星形孢子素和蛋白激酶抑制剂的影响，但可以被丝氨酸/苏氨酸蛋白磷酸酶2A完全和特异性地失活。该酶被过渡金属和对氯苯甲酸汞完全抑制但可逆，并被多聚L赖氨酸对大部分但不是全部蛋白质底物强烈刺激。比较了放线菌亚胺刺激的MAP-2激酶(pp54 MAP-2)与胰岛素刺激的MAP-2激酶(Pp42)对潜在多肽底物的活性。尽管两个MAP-2激酶都很少或根本没有能力磷酸化组蛋白和酪蛋白，但这两个激酶具有明显的底物特异性。在类似的MAP-2磷酸化活性下，pp42的MAP-2激酶，而不是pp54的MAP-2，磷酸化并激活了非洲爪哇S6蛋白激酶II。此外，pp42的MAP-2蛋白磷酸化的速率是pp54的10-12倍。放线菌亚胺激活的pp54 MAP-2蛋白激酶似乎是一种以前未知的蛋白激酶，它本身受Ser/Thr磷酸化调节，可能还受具有碱性结构域的多肽调节剂的调节。上游调控元件和天然底物的同一性仍有待确定。
An hepatic protein kinase that phosphorylates microtubule-associated protein 2 (MAP-2) on Ser/Thr residues is markedly activated after intraperitoneal injection of cycloheximide in the rat. The enzyme has been purified greater than 10,000-fold to near homogeneity and corresponds to a 54-kDa polypeptide, based on auto-phosphorylation, renaturation of activity from sodium dodecyl sulfate gels, and gel filtration. The protein kinase activity is unaffected by prior autophosphorylation, Ca2+, diacylglycerol and phospholipids, cyclic nucleotides, staurosporine, and protein kinase inhibitor, but can be totally and specifically deactivated by the Ser/Thr protein phosphatase 2A. The enzyme is inhibited completely but reversible by transition metals and p-chloromercuribenzoate, and is strongly stimulated by poly-L-lysine toward most, but not all protein substrates. The activity of the cycloheximide-stimulated MAP-2 kinase (pp54 MAP-2 kinase) toward potential polypeptide substrates was compared to that of an insulin-stimulated MAP-2 kinase (pp42 MAP-2 kinase). Although both MAP-2 kinases exhibited little or no ability to phosphorylate histones and casein, the two kinases had a distinguishable substrate specificity. At comparable MAP-2 phosphorylating activities, pp42 MAP-2 kinase, but not pp54 MAP-2 kinase, phosphorylated and activated the Xenopus S6 protein kinase II. Moreover, pp42 MAP-2 kinase phosphorylated myelin basic protein at 10-12-fold higher rates than did pp54 MAP-2 kinase. Cycloheximide-activated pp54 MAP-2 protein kinase appears to be a previously uncharacterized protein kinase that is itself regulated through Ser/Thr phosphorylation and, perhaps, polypeptide regulators with basic domains. The identity of the upstream regulatory elements and the native substrates remain to be established.