Ferro K L, Collins C A
Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611-3008.
J Biol Chem. 1995 Mar 3;270(9):4492-6. doi: 10.1074/jbc.270.9.4492.
In this study we report that phospholipid vesicles activate ATP hydrolysis by cytoplasmic dynein but not kinesin, consistent with reported differences in the organelle/vesicle binding of these motor proteins. Dynein activation by phospholipids was comparable with that seen in the presence of microtubules but was not sensitive to moderate salt concentrations and was independent of the net charge of the phospholipid, suggesting that the means of interaction between dynein and the lipid vesicle was not strictly ionic in nature. Based on this result, previous data that show that the interaction between dynein and vesicles is not ATP sensitive, and the concentration dependence observed for lipid activation of cytoplasmic dynein, it is likely that the binding interaction between dynein and liposomes is a stable one. In contrast to a previous report, microtubules increased the hydrolysis rate of all naturally occurring nucleotides tested, whereas only ATPase activity was stimulated by phospholipids. As ATP is the physiologically relevant substrate and is the only nucleotide to promote motility, the activation of only the ATPase by phospholipids may represent a means of discriminating between coupled and uncoupled nucleotide hydrolysis in vitro.
在本研究中，我们报告磷脂囊泡可激活胞质动力蛋白的ATP水解，但不能激活驱动蛋白，这与这些运动蛋白在细胞器/囊泡结合方面已报道的差异一致。磷脂对动力蛋白的激活作用与在微管存在时观察到的情况相当，但对中等盐浓度不敏感，且与磷脂的净电荷无关，这表明动力蛋白与脂质囊泡之间的相互作用方式本质上并非严格的离子相互作用。基于这一结果、先前显示动力蛋白与囊泡之间的相互作用对ATP不敏感的数据以及观察到的脂质对胞质动力蛋白激活的浓度依赖性，动力蛋白与脂质体之间的结合相互作用可能是一种稳定的相互作用。与之前的一份报告相反，微管提高了所有测试的天然存在核苷酸的水解速率，而磷脂仅刺激ATP酶活性。由于ATP是生理相关底物，且是唯一能促进运动的核苷酸，磷脂仅激活ATP酶可能代表了一种在体外区分偶联和非偶联核苷酸水解的方式。
