Lamaze C, Chuang T H, Terlecky L J, Bokoch G M, Schmid S L
Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
Nature. 1996 Jul 11;382(6587):177-9. doi: 10.1038/382177a0.
Pinocytosis and membrane ruffling are among the earliest and most dramatic cellular responses to stimulation by growth factors or other mitogens. The small Ras-related G proteins Rho and Rac have a regulatory role in membrane ruffling and activated Rho has been shown to stimulate pinocytosis when microinjected into Xenopus oocytes. In contrast to these well established effects of Rho and Rac on plasma membrane morphology and bulk pinocytosis, there has been no evidence for their involvement in the regulation of receptor-mediated endocytosis in clathrin-coated pits. Here we show that activated Rho and Rac inhibit transferrin-receptor-mediated endocytosis when expressed in intact cells. Furthermore, we have reconstituted these effects in a cell-free system and established that Rho and Rac can regulate clathrin-coated vesicle formation.
胞饮作用和膜皱襞形成是细胞对生长因子或其他促有丝分裂原刺激最早且最显著的反应之一。小的Ras相关G蛋白Rho和Rac在膜皱襞形成中起调节作用，并且已表明，当显微注射到非洲爪蟾卵母细胞中时，活化的Rho会刺激胞饮作用。与Rho和Rac对质膜形态和整体胞饮作用的这些已确定的作用相反，没有证据表明它们参与网格蛋白包被小窝中受体介导的内吞作用的调节。在这里，我们表明，活化的Rho和Rac在完整细胞中表达时会抑制转铁蛋白受体介导的内吞作用。此外，我们在无细胞系统中重建了这些作用，并确定Rho和Rac可以调节网格蛋白包被囊泡的形成。
