Department of Horticulture and Landscape Architecture, Washington State University, Pullman, Washington 99164-6414.
Plant Physiol. 1984 Oct;76(2):359-65. doi: 10.1104/pp.76.2.359.
In vitro phosphorylation of several membrane polypeptides and soluble polypeptides from corn (Zea mays var. Patriot) coleoptiles was promoted by adding Ca(2+). Ca(2+)-promoted phosphorylation of the membrane polypeptides was further increased in the presence of calmodulin. Both Ca(2+)-stimulated and Ca(2+)- and calmodulin-stimulated phosphorylations of membrane polypeptides were inhibited by chlorpromazine, a calmodulin antagonist. Ca(2+)-stimulated phosphorylation of soluble polypeptides increased with increasing Ca(2+) concentration. The calmodulin antagonists chlorpromazine and trifluoperazine inhibited the Ca(2+)-promoted phosphorylation of soluble polypeptides. Added calmodulin promoted the Ca(2+)-dependent phosphorylation of a 98 kilodaltons polypeptide. Both Ca(2+)-dependent and Ca(2+)-independent phosphorylations required Mg(2+) at an optimal concentration of 5 to 10 millimolar. Cyclic AMP was found to have no stimulatory effect on protein phosphorylation. Sodium molybdate, an inhibitor of protein phosphatase, increased the net phosphorylation of several polypeptides. Rapid loss of radioactivity from the phosphorylated polypeptides following incubation in unlabeled ATP indicated the presence of phosphoprotein phosphatase activity.
在体外，添加 Ca(2+) 可促进玉米（Zea mays var. Patriot）幼茎膜多肽和可溶性多肽的磷酸化。钙调蛋白的存在进一步增加了膜多肽的 Ca(2+)-促进磷酸化。氯丙嗪是一种钙调蛋白拮抗剂，可抑制膜多肽的 Ca(2+)-刺激和 Ca(2+)-和钙调蛋白刺激的磷酸化。随着 Ca(2+)浓度的增加，可溶性多肽的 Ca(2+)-刺激磷酸化增加。钙调蛋白拮抗剂氯丙嗪和三氟拉嗪抑制可溶性多肽的 Ca(2+)-促进磷酸化。添加的钙调蛋白促进了 98 千道尔顿多肽的 Ca(2+)-依赖性磷酸化。Ca(2+)-依赖性和 Ca(2+)-非依赖性磷酸化都需要在最佳浓度为 5 至 10 毫摩尔的 Mg(2+)。环 AMP 被发现对蛋白质磷酸化没有刺激作用。钼酸钠是一种蛋白磷酸酶抑制剂，可增加几种多肽的净磷酸化。在未标记的 ATP 孵育后，从磷酸化多肽中快速失去放射性表明存在磷酸蛋白磷酸酶活性。
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