Stx1B

Stx1B, short for syntaxin-1B, is a neuronal membrane protein encoded by the STX1B gene in humans. It is a member of the syntaxin family of SNARE proteins and serves as one of the target (t-) SNAREs on the presynaptic plasma membrane.

In chemical synapses, syntaxin-1B participates in the formation of the SNARE complex with SNAP-25 and synaptobrevin/VAMP2 on synaptic vesicles. This complex brings the vesicle and plasma membranes into close proximity and mediates calcium-triggered fusion, enabling rapid neurotransmitter release.

Stx1B is predominantly expressed in the nervous system, with strong localization to presynaptic active zones in various brain regions. It often coexists with syntaxin-1A and other SNAREs. Its activity is modulated by interactions with regulatory proteins such as Munc18-1 (STXBP1) and Munc13; the SNARE complex is disassembled by NSF and α-SNAP after fusion.

Genetic and clinical notes: Variants in STX1B have been associated with epilepsy phenotypes, including febrile seizures and epileptic encephalopathy, in humans. In vitro and in vivo studies suggest that pathogenic variants can disrupt SNARE complex formation and neurotransmitter release, contributing to abnormal neuronal excitability. STX1B mutations are relatively rare but are recognized in neurodevelopmental and epileptic disorders.

Research context: Animal models, including mice with altered STX1B expression, show changes in evoked neurotransmitter release and synaptic plasticity, underscoring the essential role of syntaxin-1B in fast synaptic transmission.