Binding contribution between synaptic vesicle membrane and plasma membrane proteins in neurons: an AFM study.

The final step in the exocytotic process is the docking and fusion of membrane-bound secretory vesicles at the cell plasma membrane. This docking and fusion is brought about by several participating vesicle membrane, plasma membrane and soluble cytosolic proteins. A clear understanding of the interactions between these participating proteins giving rise to vesicle docking and fusion is essential. In this study, the binding force profiles between synaptic vesicle membrane and plasma membrane proteins have been examined for the first time using the atomic force microscope. Binding force contributions of a synaptic vesicle membrane protein VAMP1, and the plasma membrane proteins SNAP-25 and syntaxin, are also implicated from these studies. Our study suggests that these three proteins are the major, if not the only contributors to the interactive binding force that exist between the two membranes.