Membrane fusion by VAMP3 and plasma membrane t-SNAREs.
Pairing of SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins on vesicles (v-SNAREs) and SNARE proteins on target membranes (t-SNAREs) mediates intracellular membrane fusion. VAMP3/cellubrevin is a v-SNARE that resides in recycling endosomes and endosome-derived transport vesicles. VAMP3 has been implicated in recycling of transferrin receptors, secretion of alpha-granules in platelets, and membrane trafficking during cell migration. Using a cell fusion assay, we examined membrane fusion capacity of the ternary complexes formed by VAMP3 and plasma membrane t-SNAREs syntaxin1, syntaxin4, SNAP-23 and SNAP-25. VAMP3 forms fusogenic pairing with t-SNARE complexes syntaxin1/SNAP-25, syntaxin1/SNAP-23 and syntaxin4/SNAP-25, but not with syntaxin4/SNAP-23. Deletion of the N-terminal domain of syntaxin4 enhanced membrane fusion more than two fold, indicating that the N-terminal domain negatively regulates membrane fusion. Differential membrane fusion capacities of the ternary v-/t-SNARE complexes suggest that transport vesicles containing VAMP3 have distinct membrane fusion kinetics with domains of the plasma membrane that present different t-SNARE proteins.
Hu
Chuan
C
Department of Physiology and Pharmacology, West Virginia University Health Sciences Center, Morgantown, WV 26506, USA. chuan.hu@louisville.edu
Hardee
Deborah
D
Minnear
Fred
F
D000818:Animals; D019556:COS Cells; D002462:Cell Membrane / Q000502:physiology*; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D008561:Membrane Fusion / Q000502:physiology*; D051379:Mice; D009154:Mutation; D050765:Qa-SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D050766:Qb-SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D050767:Qc-SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D050825:Synaptosomal-Associated Protein 25 / Q000235:genetics / Q000378:metabolism*; D051040:Vesicle-Associated Membrane Protein 3 / Q000235:genetics / Q000378:metabolism*
D050765:Qa-SNARE Proteins; D050766:Qb-SNARE Proteins; D050767:Qc-SNARE Proteins; C107017:Snap23 protein, mouse; D050825:Synaptosomal-Associated Protein 25; D051040:Vesicle-Associated Membrane Protein 3; C494953:vesicle-associated membrane protein 3, mouse