May participate in the regulation of synaptic vesicle docking and fusion, possibly through interaction with GTP-binding proteins. Essential for neurotransmission and binds syntaxin, a component of the synaptic vesicle fusion machinery probably in a 1:1 ratio. Can interact with syntaxins 1, 2, and 3 but not syntaxin 4. May play a role in determining the specificity of intracellular fusion reactions.
Brain and spinal cord. Highly enriched in axons.
Involvement in disease
Defects in STXBP1 are the cause of epileptic encephalopathy early infantile type 4 (EIEE4) [MIM:612164]. Affected individuals have neonatal or infantile onset of seizures, suppression-burst pattern on EEG, profound mental retardation, and MRI evidence of hypomyelination.
Confocal immunofluorescent analysis of methanol-fixed A431 cells labeling Munc18 with ab155020 at 1/500 dilution (green). Alpha-tubulin filaments were labeled with an Alpha-tubulin antibody at 1/2000 dilution (red).