High impact information on STXBP5

• High level expression of either syntaxin-1 or tomosyn results in a specific reduction in Ca2+-dependent exocytosis from PC12 cells [1].
• We found that pancreatic beta-cells express different isoforms of tomosyn-1, a syntaxin-1-binding protein possessing a SNARE-like motif [2].
• Taken together, our data suggest that tomosyn-1 is involved in a post-docking event that prepares secretory granules for fusion and is necessary to sustain exocytosis of pancreatic beta-cells in response to insulin secretagogues [2].
• Replacement of endogenous tomosyn-1 with mouse tomosyn-1, which differs in the nucleotide sequence from its rat homologue and escapes silencing, restored a normal secretory rate [2].
• Silencing of tomosyn-1 in the rat beta-cell line INS-1E by RNA interference did not affect the number of secretory granules docked at the plasma membrane but led to a reduction in stimulus-induced exocytosis [2].

Biological context of STXBP5

• Using microarrays to facilitate positional cloning: identification of tomosyn as an inhibitor of neurosecretion [3].

Other interactions of STXBP5

• Characterization of tom-1 mutants suggests that TOM-1, the C. elegans ortholog of mammalian tomosyn, functions as an endogenous inhibitor of neurotransmitter secretion [3].

Analytical, diagnostic and therapeutic context of STXBP5

• Using atomic force microscopy we show that the SNARE-like domain of tomosyn-1 can form a complex with syntaxin-1 and SNAP25 but displays binding forces that are weaker than those observed for VAMP2 (237+/-13 versus 279+/-3 pN) [2].

References