According to a popular model, membrane fusion occurs when soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins on one membrane form a complex with SNARE proteins on another.
Barry Lentz of the University of North Carolina, Chapel Hill, Axel Brunger of Stanford University, and colleagues have now shown that SNARE complex formation does not automatically lead to membrane fusion.1 It wasn't the first paper to do that, notes Faculty of 1000 member Josep Rizo, of the University of Texas Southwestern Medical Center in Dallas, but "this study is particularly compelling."
"Physiological membrane fusion requires lipid mixing to form a single bilayer, but you don't want the contents of the vesicles to leak out. So you have to demonstrate a series of criteria that have been defined by lipid biophysicists. Previous studies demonstrated lipid mixing induced by...
"The message is that the model appears to be inaccurate. It doesn't mean that SNAREs do not participate in fusion. What it means is that they probably cannot do it alone."