Complexin-1 (CPX I; also synaphin-2) is a 17-18 kDa, cytosolic protein that belongs to the complexin/synaphin family, complexin-1/-2 subfamily of molecules. It is expressed in select neurons and pancreatic beta -cells, and serves as a block against premature neurotransmitter/insulin granule release. Both Complexin-1 and Complexin-2 bind to the SNARE complex that contains SNAP25, VAMP2 and STX1A, generating oligomers of SNARE complexes that are optimally oriented relative to the positions of vesicle and plasma membranes. This effectively places synaptic vesicles in an optimal configuration, allowing for a coordinated, uniform fusion and release upon appropriate stimulus. Typically, complexin-1 is described as a clamp that blocks (vesicle) fusion, and the stimulus that overcomes it is one that induces an influx of synaptotagmin-detectable calcium. Human complexin-1 is 134 amino acids (aa) in length. It contains one coiled-coil domain (aa 29-69) that incorporates part of a SNARE complex interaction sequence (aa 48-70). Full-length human complexin-1 shares 97% aa sequence identity with mouse complexin-1.
| Uniprot | Human |
| Product By Gene ID | 10815 |
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