Fig. 2. SNARE complex assembly and its control. (A) Interaction of syntaxin with nSec1, also known as Munc18 (1DN1) (Yang et al., 2000). nSec1 binds to the closed conformation of syntaxin, regulating its availability. (B) Binding of Sly1 to the N-terminal peptide of the SNARE Sed5 may function similarly (1MQS) (Bracher and Weissenhorn, 2002). (C) The open conformation of the syntaxin molecule (as shown in Fig. 1C). (D) The assembled SNARE complex modeled between two membranes (1SFC) (Sutton et al., 1998). (E) Interaction of complexin with the SNARE complex might regulate exocytosis (1KIL) (Chen et al., 2002).