unc 18

Participates in the regulation of synaptic vesicle docking and fusion 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.

Participates in the regulation of synaptic vesicle docking and fusion 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.

Syntaxin-binding protein 3, also known as Platelet Sec1 protein, Protein unc-18 homolog 3, Protein unc-18 homolog C, Unc-18C, Unc18-3 and STXBP3, is a cytoplasm protein which belongs to the STXBP/unc-18/SEC1 family. STXBP3 is expressed in cells that exhibit granule exocytosis, such as neutrophils, mast cells, platelets and endothelial cells. STXBP3, together with STX4 and VAMP2, may play a role in insulin-dependent movement of GLUT4 and in docking / fusion of intracellular GLUT4-containing vesicles with the cell surface in adipocytes. STXBP3 participates in the consolidation and secretion of secondary and tertiary granules. STXBP3 contains one SEC1 domain. Phosphorylation at Ser129 may stimulate granule release. Human STXBP3 shares 9% aa identity with mouse STXBP3. STXBP3 interacts with DOC2B; the interaction is direct, occurs at the cell membrane, excludes interaction with STX4 and regulates glucose-stimulated insulin secretion. Interacts with STX4.

Syntaxin-binding protein 1, also known as N-Sec1, Protein unc-18 homolog 1, MUNC18-1 and STXBP1, is a peripheral membrane protein that belongs to the STXBP / unc-18 / SEC1 family. STXBP1 is an evolutionally conserved neuronal Sec1/Munc-18 (SM) protein that is essential in synaptic vesicle release in several species. It may participate in the regulation of synaptic vesicle docking and fusion, possibly through interaction with GTP-binding proteins. STXBP1 is essential for neurotransmission and binds syntaxin, a component of the synaptic vesicle fusion machinery probably in a 1:1 ratio. It can interact with syntaxins 1, 2, and 3 but not syntaxin 4. STXBP1 may also play a role in determining the specificity of intracellular fusion reactions. Defects in STXBP1 are the cause of epileptic encephalopathy early infantile type 4 (EIEE4). Affected individuals have neonatal or infantile onset of seizures, suppression-burst pattern on EEG, profound mental retardation, and MRI evidence of hypomyelination.