Syntaxins are potentially involved in the docking of synaptic vesicles at presynaptic active zones and may play a key role in neurotransmitter exocytosis. Three isoforms are produced by alternative splicing. Isoform 1 is expressed in embryonic spinal chord and ganglia and in adult cerebellum and cerebral cortex. Isoform 2 is expressed in heart, liver, fat, skeletal muscle, kidney and brain. Syntaxin 1A interacts with VAPA and SYBU and is a member of the SNARE core complex containing SNAP25 and VAMP2. In addition, it is found in complexes with SNAP25, SNAP23 and VAMP8. Haploinsufficiency of STX1A may result in particular cardiovascular and musculo-skeletal abnormalities observed in Williams-Beuren syndrome, a rare developmental disorder.