Oda H, Stockert R J, Collins C, Wang H, Novikoff P M, Satir P, Wolkoff A W
Marion Bessin Liver Research Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
J Biol Chem. 1995 Jun 23;270(25):15242-9. doi: 10.1074/jbc.270.25.15242.
In a recent study (Goltz, J.S., Wolkoff, A.W., Novikoff, P.M., Stockert, R.J., and Satir, P. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 7026-7030), we found that ligand- and receptor-containing endocytic vesicles bind to endogenous microtubules in vitro after 60 min of receptor-mediated endocytosis of asialo-orosomucoid. In the presence of ATP, ligand-containing endocytic vesicles are released from microtubules, while those containing receptor are not. We hypothesized that cytoplasmic dynein may associate with ligand-containing, but not receptor-containing, domains of endocytic vesicles and might be involved in the movement of ligand-containing vesicles along microtubules during sorting of ligand from receptor. Direct evidence in support of this hypothesis has been obtained in the present study. Binding of ligand-containing vesicles to microtubules correlates highly (p < 0.001) with binding of dynein, but not kinesin, under a variety of conditions. Binding of receptor-containing vesicles to microtubules is independent of both cytoplasmic dynein and kinesin binding. Tight association of cytoplasmic dynein with a population of ligand-containing vesicles is seen directly by immunoprecipitation. These results support the view that in receptor-mediated endocytosis, ligand-containing vesicles become bound to microtubules by cytoplasmic dynein. While receptor domains of endosomes remain attached to microtubules in an ATP-independent manner, ligand-containing domains might be moved away toward pericentrosomal lysosomes by this motor molecule.
在最近的一项研究中（戈尔茨，J.S.，沃尔科夫，A.W.，诺维科夫，P.M.，斯托克特，R.J.，以及萨蒂尔，P.（1992年）《美国国家科学院院刊》89卷，7026 - 7030页），我们发现，在脱唾液酸血清类黏蛋白经受体介导的内吞作用60分钟后，含有配体和受体的内吞小泡在体外与内源性微管结合。在ATP存在的情况下，含有配体的内吞小泡从微管上释放，而含有受体的小泡则不会。我们推测，胞质动力蛋白可能与内吞小泡中含配体而非含受体的结构域相关联，并且在配体与受体分选过程中，可能参与含配体小泡沿微管的移动。在本研究中已获得支持这一推测的直接证据。在多种条件下，含配体小泡与微管的结合与动力蛋白而非驱动蛋白的结合高度相关（p < 0.001）。含受体小泡与微管的结合与胞质动力蛋白和驱动蛋白的结合均无关。通过免疫沉淀可直接观察到胞质动力蛋白与一群含配体小泡紧密关联。这些结果支持这样一种观点，即在受体介导的内吞作用中，含配体小泡通过胞质动力蛋白与微管结合。虽然内涵体的受体结构域以不依赖ATP的方式保持与微管附着，但含配体结构域可能通过这种分子马达朝着中心体周围的溶酶体移动。
