SNAREs and Rab GTPases cooperate in vesicle transport through a mechanism yet poorly understood. We now demonstrate that the Rab5 effectors EEA1 and Rabaptin-5/Rabex-5 exist on the membrane in high molecular weight oligomers, which also contain NSF. Oligomeric assembly is modulated by the ATPase activity of NSF. Syntaxin 13, the t-SNARE required for endosome fusion, is transiently incorporated into the large oligomers via direct interactions with EEA1. This interaction is required to drive fusion, since both dominant-negative EEA1 and synthetic peptides encoding the FYVE Zn2+ finger hinder the interaction and block fusion. We propose a novel mechanism whereby oligomeric EEA1 and NSF mediate the local activation of syntaxin 13 upon membrane tethering and, by analogy with viral fusion proteins, coordinate the assembly of a fusion pore.
|Publication status||Published - 1999|
Bibliographical noteM1 - 3
- Adenosinetriphosphatase/metabolism Amino Acid Sequence Autoantigens/metabolism Biosensing Techniques Carrier Proteins/*metabolism Endosomes/drug effects/physiology GTP Phosphohydrolases/metabolism GTP-Binding Proteins/*metabolism Hela Cells Human Intracellular Membranes/drug effects/physiology/ultrastructure Membrane Fusion/drug effects/*physiology Membrane Proteins/*metabolism Models, Biological Molecular Sequence Data Oligopeptides/chemistry/pharmacology Peptide Fragments/chemistry/pharmacology Support, Non-U.S. Gov't Zinc Fingers rab5 GTP-Binding Proteins