Rabaptin-5 is a direct effector of the small GTPase Rab5 in endocytic membrane fusion
1995; Cell Press; Volume: 83; Issue: 3 Linguagem: Inglês
10.1016/0092-8674(95)90120-5
ISSN1097-4172
AutoresHarald Stenmark, Gaetano Vitale, Oliver Ullrich, Marino Zerial,
Tópico(s)Erythrocyte Function and Pathophysiology
ResumoWe have identified a novel 100 kDa coiled-coil protein, rabaptin-5, that specifically interacts with the GTP form of the small GTPase Rab5, a potent regulator of endocytic transport. It is mainly cytosolic, but a fraction colocalizes with Rab5 to early endosomes. Expression of a GTPase-deficient Rab5 mutant enhances the binding of rabaptin-5 to enlarged endosomes. Overexpression of rabaptin-5 alone is sufficient to promote expansion of early endosomes. Rab5 recruits rabaptin-5 to purified early endosomes in a GTP-dependent manner, demonstrating functional similarities with other members of the Ras superfamily. Immunodepletion of rabaptin-5 from cytosol strongly inhibits Rab5-dependent early endosome fusion. Rabaptin-5 is thus a Rab effector required for membrane docking and fusion.
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