A family of proteins involved in regulating exocytosis, particularly the release of neurotransmitter at synapses. Complexin-1 (synaphin-2, 134 aa) binds to the SNARE core complex (SNAP25, synaptobrevin, and syntaxin) and positively regulates a late step in synaptic vesicle exocytosis by inhibitory neurons. It is also involved in glucose-induced secretion of insulin by pancreatic beta cells. It is overexpressed in the substantia nigra in Parkinson's disease. Complexin-2 (synaphin-1, 134 aa) is also involved in regulating synaptic vesicle exocytosis, but mainly in excitatory neurons, and is involved in mast cell exocytosis. It is down-regulated in brain cortex in Huntington's disease, bipolar disorder, and major depression and is down-regulated in the cerebellum in schizophrenia. Complexin-3 (158 aa) and complexin-4 (160 aa) also regulate synaptic vesicle release.
Subjects: Medicine and Health.