Peltz G, Spudich J A, Parham P
J Cell Biol. 1985 Apr;100(4):1016-23. doi: 10.1083/jcb.100.4.1016.
Ten monoclonal antibodies (My1-10) against Dictyostelium discoideum myosin were prepared and characterized. Nine bound to the 210-kD heavy chain and one (My8) bound to the 18-kD light chain. They defined six topographically distinct antigenic sites of the heavy chain. Five binding sites (the My1, My5, My10 site, and the My2, My3, My4, and My9 sites) are located on the rod portion of the myosin molecule. The position of the sixth site (the My6 and My7 site) is less certain, but it appears to be near the junction of the globular heads and the rod. Three of the antibodies (My2, My3, and My6) bound to myosin filaments in solution and could be sedimented in stoichiometric amounts with the filamentous myosin. In contrast, My4, which recognized a site on the rod, inhibited the polymerization of monomeric myosin into filaments. A single antibody (My6) affected the actin-activated ATPase of myosin. The nature of the effect depended on the valency of the antibody and the myosin. Bivalent IgG and F(ab')2 fragments of My6 inhibited the actin-activated ATPase of filamentous myosin by 50% whereas univalent Fab' fragments increased the activity by 50%. The actin-activated ATPase activity of the soluble chymotryptic fragment of myosin was increased 80-90% by both F(ab')2 and Fab' of My6.
制备并表征了十种针对盘基网柄菌肌球蛋白的单克隆抗体（My1 - 10）。九种抗体与210-kD重链结合，一种（My8）与18-kD轻链结合。它们定义了重链上六个拓扑学上不同的抗原位点。五个结合位点（My1、My5、My10位点以及My2、My3、My4和My9位点）位于肌球蛋白分子的杆状部分。第六个位点（My6和My7位点）的位置不太确定，但似乎靠近球状头部与杆状部分的交界处。其中三种抗体（My2、My3和My6）能与溶液中的肌球蛋白丝结合，并能与丝状肌球蛋白以化学计量的量一起沉淀。相比之下，识别杆状部分一个位点的My4抑制单体肌球蛋白聚合成丝。单一抗体（My6）影响肌球蛋白的肌动蛋白激活的ATP酶活性。这种影响的性质取决于抗体和肌球蛋白的价态。My6的二价IgG和F(ab')2片段抑制丝状肌球蛋白的肌动蛋白激活的ATP酶活性达50%，而单价Fab'片段则使活性增加50%。My6的F(ab')2和Fab'都使肌球蛋白的可溶性胰凝乳蛋白酶片段的肌动蛋白激活的ATP酶活性提高了80 - 90%。
