Effect of monoclonal antibodies on the properties of smooth muscle myosin.
Effect of monoclonal antibodies on the properties of smooth muscle myosin.
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单克隆抗体对平滑肌肌球蛋白特性的影响。
DOI：
10.1021/bi00439a034
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发表时间：
1989
期刊：
影响因子：
2.9
通讯作者：
Hartshorne,DJ
中科院分区：
文献类型：
--
作者：
Ito,M;Pierce,PR;Allen,RE;Hartshorne,DJ
1989年3月16日收到的修订版摘要：制备了抗火鸡肌球蛋白的单克隆抗体，并测定了它们对肌球蛋白某些性质的影响。在低离子强度下（即用10 S肌球蛋白），抗亚片段2抗体可增强肌球蛋白的Ca ~（2+）-和Mg ~（2+）-ATP酶活性。抗S2 IgM的胰蛋白酶片段也激活这些活性。针对亚片段1和轻酶解肌球蛋白的抗体没有影响。重酶解肌球蛋白的Mg ~（2+）-ATP酶活性也被抗S_2抗体激活。在低MgCl_2浓度下，抗S_2 IgM片段可增强磷酸化肌球蛋白的肌动蛋白激活ATP酶活性。这种增加反映了5倍的Kmax增加和肌动蛋白的表观解离常数略有下降。肌动蛋白激活的去磷酸化肌球蛋白ATP酶不受完整的抗S2抗体或其片段的影响。肌球蛋白与抗S2抗体相互作用可使20000-道尔顿轻链的磷酸化和去磷酸化速率增加。肌球蛋白的有限蛋白水解被用作构象探针。抗S2抗体与10 S肌球蛋白的相互作用增加了S1-S2连接处的切割程度。6S肌球蛋白的蛋白水解迅速，不受抗S2抗体的影响。我们对这些结果的解释是，抗S2抗体与肌球蛋白的相互作用改变了S2区的构象，这反过来又改变了肌球蛋白的一些性质。这与平滑肌肌球蛋白的S2区是其生物学特性的决定因素的假设是一致的。
Revised Manuscript Received March 16, 1989 abstract: Monoclonal antibodies were generated against turkey gizzard myosin, and their effects on some of the properties of myosin were assayed. Ca2+-andMg2+-ATPase activities of myosin were enhanced by the anti-subfragment 2 antibodies at low ionic strength (ie, with 10S myosin). Tryptic fragments of an anti-S2 IgM also activated these activities. Antibodies directed against subfragment 1 and light meromyosin had no effect. The Mg2+-ATPase activity of heavy meromyosin also was activated by an anti-S2 antibody. Actin-activated ATPase activity of phosphorylatedmyosin was enhanced by the anti-S2 IgM fragments at low MgCl2 concentrations. This increase was reflected by a 5-fold increase in Kmax and a slight decrease in the apparent dissociation constant for actin. The actin-activated ATPase of dephosphorylated myosin was not affected by intact anti-S2 antibody or its fragments. The rates of phosphorylation and dephos-phorylation of the 20 000-dalton light chains were increased by interaction of myosin with anti-S2 antibody. Limited proteolysis of myosin was used as a conformational probe. Interaction of anti-S2 antibody with 10S myosin increased the extent of cleavage at the S1-S2 junction. Proteolysis of 6S myosin was rapid and was not influenced by anti-S2 antibody. Our interpretation of these results is that interaction of the anti-S2 antibodies with myosin alters the conformation in the S2 region and this in turn modifies some of the properties of myosin. This is consistent with the hypothesis that the S2 region of smooth muscle myosin is a determinant of its biological properties.