Complexin (also known as synaphin) refers to a one of a small set of eukaryotic cytoplasmic neuronal proteins which binds to the SNARE protein complex (SNAREpin) with a high affinity. These are called synaphin 1 and 2. In the presence of Ca2+, the transport vesicle protein synaptotagmin displaces complexin, allowing the SNARE protein complex to bind the transport vesicle to the presynaptic membrane.
Complexin acts as both an inhibitor and a facilitator of synaptic vesicle fusion and neurotransmitter release. In one conformation, it clamps SNAREpin complexes, preventing vesicle fusion, while in a different conformation it releases the SNAREpins, allowing synaptotagmin to trigger fusion.[1]
Whereas complexin is not necessary for synaptic vesicle exocytosis, it does increase neurotransmitter release by 60–70% as demonstrated by complexin gene knockout in mice.[2] A number of human neurological diseases have been linked to a deficiency of complexin.
Synaphin can promote exocytosis by promoting interaction between the complementary syntaxin and synaptobrevin transmembrane regions that reside in opposing membranes prior to fusion.[2]
^Krishnakumar, Shyam; Radoff, Daniel; Kuemmel, Daniel; Giraudo, Claudio; Li, Feng; Khandan, Lavan; Wood Baguely, Stephanie; Coleman, Jeff; Reinisch, Karin; Pincet, Frederic; Rothman, James (August 2011). "A conformational switch in complexin is required for synaptotagmin to trigger synaptic fusion". Nature Structural & Molecular Biology. 18 (8): 934–940. doi:10.1038/nsmb.2103. PMC 3668341. PMID 21785412.
^ abHu K, Carroll J, Rickman C, Davletov B (2002). "Action of complexin on SNARE complex". J Biol Chem. 277 (44): 41652–6. doi:10.1074/jbc.M205044200. PMID 12200427.
Complexin (also known as synaphin) refers to a one of a small set of eukaryotic cytoplasmic neuronal proteins which binds to the SNARE protein complex...
presynaptic membrane. It was also shown that synaptotagmin 1 can displace complexin from the SNARE complex in the presence of calcium. This is thought to...
molecule Complexin within the SNARE complex and its interaction with the molecule synaptotagmin. Known as the "clamp" hypothesis, the presence of complexin normally...
technology Yoon-tae Young, physicist; first to observe proper function of complexin protein to control neuron communication Giltsu Choi, photobiologist; identified...
Complexin-2 is a protein that in humans is encoded by the CPLX2 gene. Proteins encoded by the complexin/synaphin gene family are cytosolic proteins that...
Complexin-1 is a protein that in humans is encoded by the CPLX1 gene. Proteins encoded by the complexin/synaphin gene family are cytosolic proteins that...
stable complex with syntaxin, synaptosomal-associated protein, 25 kD, and complexin. It also forms a distinct complex with synaptophysin. Heterozygous mutations...
SNARE motifs form a stable interaction between the vesicle and membrane. Complexins stabilize the primed SNARE-complex rendering the vesicles ready for rapid...
early to late endosomes and lysosomes Endosome, plasma membrane CPLX4 (Complexin-4) Q7Z7G2 Regulates SNARE protein complex-mediated synaptic vesicle fusion...
neurotransmitter (see below: releasable pool). After the vesicle is primed then complexin binds to the SNARE complex this is called "superprimed". The vesicles...
(2005). "Decreased expression of vesicular glutamate transporter 1 and complexin II mRNAs in schizophrenia: further evidence for a synaptic pathology affecting...
Suzuki, T.; Kirino, Y.; Abe, T. (1997). "Molecular cloning of synaphins/complexins, cytosolic proteins involved in transmitter release, in the electric organ...
TC, Jahn R, Rizo J, Fasshauer D (Jun 2000). "Selective interaction of complexin with the neuronal SNARE complex. Determination of the binding regions"...
v t e PDB gallery 1kil: Three-dimensional structure of the complexin/SNARE complex 1n7s: High Resolution Structure of a Truncated Neuronal SNARE Complex...
v t e PDB gallery 1kil: Three-dimensional structure of the complexin/SNARE complex 1n7s: High Resolution Structure of a Truncated Neuronal SNARE Complex...
SNARE region of syntaxin 1a 1kil: Three-dimensional structure of the complexin/SNARE complex 1n7s: High Resolution Structure of a Truncated Neuronal...
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