Syntaxin-binding protein 1 (also known as Munc18-1) is a protein that in humans is encoded by the STXBP1 gene. This gene encodes a syntaxin-binding protein. The encoded protein appears to play a role in release of neurotransmitters via regulation of syntaxin, a transmembrane attachment protein receptor. Mutations in this gene have been associated with neurological disorders including epilepsy, intellectual disability, and movement disorders. The encoded protein may participate in the regulation of synaptic vesicle docking and fusion, possibly through interaction with GTP-binding proteins. It is essential for neurotransmission and binds syntaxin, a component of the synaptic vesicle fusion machinery probably in a 1:1 ratio. It can interact with syntaxins 1, 2, and 3 but not syntaxin 4 and may play a role in determining the specificity of intracellular fusion reactions. This protein functions in a late stage of the intracellular membrane fusion process of exocytosis. Dissociation of this protein from syntaxin determines the kinetics of postfusion events. This protein is essential for presynpatic vesicle release and is rapidly phosphorylated by protein kinase C upon neuronal depolarization. The protein participates in the secretory pathway between the Golgi apparatus and cell membrane.