Fig. 7.

Model of syb-2 dynamics and lipid binding in SNARE zippering and membrane fusion. In its precomplex state, syb-2 binds in a highly transient equilibrium to the vesicle membrane. Additionally, syb-2 shows decreasing flexibility from the N-terminal region to the C-terminal region that influences the rate of SNARE zippering. During exocytosis, intrinsic syb-2 membrane binding may help to compensate for repulsive forces between membranes and/or membranes and negatively charged side chains in the SNARE motifs, facilitating membrane fusion.