Regulation of the UNC-18-Caenorhabditis elegans syntaxin complex by UNC-13

The Caenorhabditis elegans unc-13, unc-18, and unc-64 genes are required for normal synaptic transmission. The UNC-18 protein binds to the unc-64 gene product C. elegans syntaxin (Ce syntaxin). However, it is not clear how this protein complex is regulated. We show that UNC-13 transiently interacts with the UNC-18-Ce syntaxin complex, resulting in rapid displacement of UNC-18 from the complex. Genetic and biochemical evidence is presented that UNC-13 contributes to the modulation of the interaction between UNC-18 and Ce syntaxin.