Sakakibara H, Nakayama H
Communications Research Laboratory, Kobe, Japan.
J Cell Sci. 1998 May;111 ( Pt 9):1155-64. doi: 10.1242/jcs.111.9.1155.
Three kinds of subparticles of Chlamydomonas outer-arm dynein containing the alphabeta, beta and gamma heavy chains were isolated and assayed for their activities to translocate microtubules in vitro. All of them had activities to form bundles of microtubules in solution in an ATP-dependent manner and, when adsorbed on an appropriate glass surface, translocated microtubules. The alphabeta subparticle readily translocated microtubules on a silicone-coated glass surface with a velocity of 4.6 micron/second at 1 mM ATP. The beta subparticle translocated microtubules after it had been preincubated with tubulin dimer and when the Brownian movement of microtubules was suppressed by addition of methylcellulose. The velocity was on average 0.7 micron/second. The gamma subparticle translocated microtubules after being preincubated with tubulin dimer and adsorbed onto a silicone-coated glass surface. The velocity was about 3.8 micron/second. The tubulin dimer appeared to facilitate in vitro motility by blocking the ATP-insensitive binding of dynein subparticles to microtubule. The alphabeta, beta and gamma subparticles were thus found to have different properties as motor proteins. In addition, these subparticles showed different dependencies upon the potassium acetate concentration. Hence the outer-arm dynein of Chlamydomonas is a complex of motor proteins with different properties.
分离出衣藻外臂动力蛋白的三种亚颗粒，它们分别含有αβ、β和γ重链，并对其在体外转运微管的活性进行了测定。所有亚颗粒都具有以ATP依赖的方式在溶液中形成微管束的活性，并且当吸附在合适的玻璃表面时，能够转运微管。αβ亚颗粒在1 mM ATP浓度下，能以4.6微米/秒的速度在硅酮涂层玻璃表面轻松转运微管。β亚颗粒在与微管蛋白二聚体预孵育后，且通过添加甲基纤维素抑制微管的布朗运动时，能够转运微管，平均速度为0.7微米/秒。γ亚颗粒在与微管蛋白二聚体预孵育并吸附到硅酮涂层玻璃表面后，能够转运微管，速度约为3.8微米/秒。微管蛋白二聚体似乎通过阻断动力蛋白亚颗粒与微管的ATP不敏感结合来促进体外运动。因此，发现αβ、β和γ亚颗粒作为运动蛋白具有不同的特性。此外，这些亚颗粒对醋酸钾浓度表现出不同的依赖性。因此，衣藻的外臂动力蛋白是具有不同特性的运动蛋白复合物。
