Membrane fusion SNAREs an inhibitor

Two membranes fuse into one through the action of SNARE proteins. As only particular combinations of t-SNAREs (on the target membrane) and v-SNAREs (on the vesicle) will cause fusion between bilayers, restricting their localization promotes fusion in the right place. On page 79, Varlamov et al. add a new layer to the regulation by showing that some SNAREs actually block fusion that would otherwise occur in the wrong place.

SNARE specificity forms two mutually exclusive systems in the Golgi—one enriched at the cis and one at the trans face of the Golgi. The concentration of cis t-SNAREs at the cis face of the Golgi, where trans t-SNAREs are scarce, helps prevent vesicles bearing trans v-SNAREs from fusing there and vice versa. But even an imperfect distribution of t-SNAREs may be offset by inhibitory SNAREs...