SNAP-29: A general SNARE protein that inhibits SNARE disassembly and is implicated in synaptic transmission

Using the yeast two-hybrid system with syntaxin-1A as bait, we isolated sol uble NSF attachment protein (SNAP)-29 from a human brain cDNA library. Syna ptosomal fractionation and immunocytochemical staining of hippocampal neuro ns in culture showed that SNAP-29 is present at synapses and is predominant ly associated with synaptic vesicles. The interaction of SNAP-29 with synta xin-1 was further confirmed with immunoprecipitation analysis. Binding comp etition studies with SNAP-29 demonstrated that it could compete with a-SNAP for binding to synaptic SNAP receptors (SNARES) and consequently inhibit d isassembly of the SNARE complex. Introduction of SNAP-29 into presynaptic s uperior cervical ganglion neurons in culture significantly inhibited synapt ic transmission in an activity-dependent manner. Although SNAP-29 has been suggested to be a general SNARE component in membrane trafficking, our find ings suggest that it may function as a regulator of SNARE complex disassemb ly and modulate the process of postfusion recycling of the SNARE components .