In vitro syntaxin per se is sufficient to drive spontaneous calcium independent fusion of synaptic vesicles containing v-SNAREs.
[5] More recent and somewhat controversial amperometric data suggest that the transmembrane domain of Syntaxin1A may form part of the fusion pore of exocytosis.
[6] Syntaxins bind synaptotagmin in a calcium-dependent fashion and interact with voltage dependent calcium and potassium channels via the C-terminal H3 domain.
Direct syntaxin-channel interaction is a suitable molecular mechanism for proximity between the fusion machinery and the gates of Ca2+ entry during depolarization of the presynaptic axonal boutons.
Recently published data show that alternative spliced Syntaxin 1 (STX1B) which lacks the transmembrane domain localizes in the nuclei.