A new beat for the SNARE drum.

Eukaryotic cells contain membrane-bound compartments that are connected by trafficking of vesicular intermediates. To maintain compartmental organization, proper targeting of transport vesicles is achieved by specific evolutionarily conserved transmembrane proteins that reside on vesicles and target membranes. According to the original SNARE hypothesis, the formation of a complex of an NEM-sensitive fusion protein (NSF), soluble NSF attachment proteins (SNAPs) and membrane-bound SNAP receptor proteins (SNAREs) ensures docking specificity and leads to membrane fusion driven by the ATPase activity of NSF. Recent results have challenged some aspects of this hypothesis and led to a reassessment of models of SNARE interactions and the events leading to vesicle docking and fusion.