Yokota E, Mabuchi I
Department of Biology, College of Arts and Sciences, University of Tokyo, Japan.
J Cell Sci. 1994 Feb;107 ( Pt 2):353-61.
C/A dynein is a novel dynein isolated from sea urchin sperm flagellar axonemes. It is composed of C and A heavy chains and some additional lower molecular mass polypeptide chains. The characterization of ATPase activity and the interaction of this dynein with microtubules polymerized from calf brain tubulin were investigated in this study. The ATPase activity of C/A dynein (0.3-0.4 mumol Pi/min per mg) was about one half that of outer arm 21 S dynein (0.6-0.8 mumol Pi/min per mg) at 25 degrees C. Vanadate inhibited the ATPase activity with a half-maximal inhibition at 1 microM. C/A dynein absorbed to the glass surface was able to translocate the microtubules towards its plus end. The velocity of the microtubule movement in the presence of 1 mM ATP was 4.0 to 4.5 microns/s at 22 degrees C. C/A dynein binds to and bundles the microtubules even in the presence of ATP. Cross-bridges were found between adjacent microtubules in the bundle with an axial periodicity of about 24 nm. The ATPase activity of C/A dynein was enhanced up to several-fold by the microtubules at concentration as low as 1 mg/ml. On the other hand, 21 S dynein bound to the microtubules with 24 nm axial periodicity only in the absence of ATP. Its ATPase activity was not activated by the microtubules. From these results, it is concluded that the manner of interaction with microtubules of C/A dynein is different from that of the outer arm dynein.
C/A动力蛋白是一种从海胆精子鞭毛轴丝中分离出的新型动力蛋白。它由C和A重链以及一些其他较低分子量的多肽链组成。本研究对这种动力蛋白的ATP酶活性以及它与从小牛脑微管蛋白聚合而成的微管之间的相互作用进行了表征。在25℃时，C/A动力蛋白的ATP酶活性（每毫克0.3 - 0.4微摩尔无机磷酸/分钟）约为外臂21S动力蛋白（每毫克0.6 - 0.8微摩尔无机磷酸/分钟）的一半。钒酸盐抑制ATP酶活性，在1微摩尔时抑制作用达到半数最大抑制。吸附在玻璃表面的C/A动力蛋白能够使微管向其正端移动。在1毫摩尔ATP存在下，22℃时微管移动速度为4.0至4.5微米/秒。即使在ATP存在的情况下，C/A动力蛋白也能结合并捆绑微管。在捆绑的相邻微管之间发现了跨桥，其轴向周期约为24纳米。当微管浓度低至1毫克/毫升时，C/A动力蛋白的ATP酶活性可增强几倍。另一方面，21S动力蛋白仅在没有ATP的情况下以24纳米轴向周期与微管结合。其ATP酶活性未被微管激活。从这些结果可以得出结论，C/A动力蛋白与微管的相互作用方式不同于外臂动力蛋白。
