Showing papers by "Sandra L. Schmid published in 1999"
TL;DR: The results indicate that dynamin, like other members of the GTPase superfamily, functions as a molecular regulator in receptor-mediated endocytosis, rather than as a force-generating GTP enzyme.
Abstract: Dynamin is a GTP-hydrolysing protein that is an essential participant in clathrin-mediated endocytosis by cells. It self-assembles into 'collars' in vitro which also formin vivo at the necks of invaginated coated pits. This self-assembly stimulates dynamin's GTPase activity and it has been proposed that dynamin hydrolyses GTP in order to generate the force needed to sever vesicles from the plasma membrane. A mechanism is now described in which self-assembly of dynamin is coordinated by a domain of dynamin with a GTPase-activating function. Unexpectedly, when dynamin mutants defective in self-assembly-stimulated GTPase activity are overexpressed, receptor-mediated endocytosis is accelerated. The results indicate that dynamin, like other members of the GTPase superfamily, functions as a molecular regulator in receptor-mediated endocytosis, rather than as a force-generating GTPase.
376 citations
TL;DR: The efficient reconstitution of ATP-, GTP-, cytosol- and dynamin-dependent formation of clathrin-coated vesicles in permeabilized 3T3-L1 cells is reported, suggesting that interactions between SH3 domains and their partners function sequentially in endocytic coated-vesicle formation.
Abstract: Several SH3-domain-containing proteins have been implicated in endocytosis by virtue of their interactions with dynamin; however, their functions remain undefined. Here we report the efficient reconstitution of ATP-, GTP-, cytosol- and dynamin-dependent formation of clathrin-coated vesicles in permeabilized 3T3-L1 cells. The SH3 domains of intersectin, endophilin I, syndapin I and amphiphysin II inhibit coated-vesicle formation in vitro through interactions with membrane-associated proteins. Most of the SH3 domains tested selectively inhibit late events involving membrane fission, but the SH3A domain of intersectin uniquely inhibits intermediate events leading to the formation of constricted coated pits. These results suggest that interactions between SH3 domains and their partners function sequentially in endocytic coated-vesicle formation.
280 citations
TL;DR: Studies on the role of cholesterol- and caveolin-rich membrane microdomains in localizing Ras to the plasma membrane and enabling its signalling activity reveal intriguing differences both between mammalian H-Ras and K-RAs and between requirements for Ras signalling in mammalian and nematode cells.
Abstract: Studies on the role of cholesterol- and caveolin-rich membrane microdomains in localizing Ras to the plasma membrane and enabling its signalling activity reveal intriguing differences both between mammalian H-Ras and K-Ras and between requirements for Ras signalling in mammalian and nematode cells.
53 citations