A common mechanism for the regulation of vesicular SNAREs on phospholipid membranes.
The SNARE (soluble N -ethylmaleimide-sensitive fusion protein attachment protein receptor) family of proteins is essential for membrane fusion in intracellular traffic in eukaryotic organisms. v-SNAREs (vesicular SNAREs) must engage target SNAREs in the opposing membrane to form the fusogenic SNARE complex. Temporal and spatial control of membrane fusion is important for many aspects of cell physiology and may involve the regulation of the SNAREs resident on intracellular membranes. Here we show that the v-SNARE synaptobrevin 2, also known as VAMP (vesicle-associated membrane protein) 2, is restricted from forming the SNARE complex in chromaffin granules from adrenal medullae to the same degree as in brain-purified synaptic vesicles. Our analysis indicates that the previously reported synaptophysin-synaptobrevin interaction is not likely to be involved in regulation of the v-SNARE. Indeed, the restriction can be reproduced for two distinct v-SNARE homologues, synaptobrevin 2 and cellubrevin/VAMP3, by reconstituting them in pure liposomal membranes. Overall, our data uncover a common mechanism for the control of SNARE engagement where intact phospholipid membranes rather than proteins down-regulate vesicular SNAREs in different cellular organelles.
Hu
Kuang
K
MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, U.K.
Rickman
Colin
C
Carroll
Joe
J
Davletov
Bazbek
B
D000818:Animals; D001921:Brain; D002352:Carrier Proteins / Q000502:physiology*; D002417:Cattle; D002837:Chromaffin Granules / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D010743:Phospholipids / Q000737:chemistry*; D050683:R-SNARE Proteins; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins; D013572:Synaptic Vesicles / Q000737:chemistry*; D016708:Synaptophysin / Q000378:metabolism / Q000502:physiology; D033921:Vesicular Transport Proteins
D002352:Carrier Proteins; D008051:Lipid Bilayers; D008081:Liposomes; D008565:Membrane Proteins; D010743:Phospholipids; D050683:R-SNARE Proteins; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins; D016708:Synaptophysin; D033921:Vesicular Transport Proteins