| Complexin-1 | |
|---|---|
| Protein Name | Complexin-1 (Cplx1) |
| Gene | CPLX1 |
| UniProt ID | O75120 |
| PDB ID | 2N1P, 5W5L |
| Molecular Weight | 15.7 kDa |
| Subcellular Localization | Presynaptic terminal |
| Protein Family | Complexin family |
Complexin-1 (Cplx1) is a small synaptic protein that plays a critical role in regulating neurotransmitter release at presynaptic terminals[1]. As a key regulator of the SNARE (Soluble N-ethylmaleimide-sensitive factor Attachment Protein Receptor) complex, complexin-1 bridges the gap between synaptic vesicle fusion machinery and the regulation of synchronous neurotransmitter release[2]. This protein has garnered significant attention in neurodegenerative disease research due to its essential role in synaptic function and its involvement in conditions such as Alzheimer's disease, Parkinson's disease, and various forms of synaptic dysfunction.
Complexin-1 is a cytosolic protein enriched in presynaptic terminals where it interacts with the SNARE complex to regulate synaptic vesicle fusion[3]. The protein functions as both a clamp that prevents premature fusion and a facilitator that promotes synchronous release when an action potential arrives. This dual function makes complexin-1 essential for precise temporal control of neurotransmitter release, which is critical for normal brain function and synaptic plasticity.
The discovery of complexin proteins emerged from studies of synaptic vesicle trafficking in the 1990s. Initial research identified complexin as a cytosolic factor that could bind to SNARE complexes and modulate their activity[4]. Subsequent studies revealed that complexin-1 and its paralog complexin-2 have distinct but overlapping functions in the nervous system, with complexin-1 being particularly important for fast synchronous release.
The molecular mechanism by which complexin-1 regulates SNARE-mediated fusion has been the subject of intense investigation. Structural studies have shown that complexin-1 contains multiple domains that interact with different parts of the SNARE complex, allowing it to function as a molecular switch that can both inhibit and promote fusion depending on the context[5].
Complexin-1 is a small synaptic protein approximately 134 amino acids in length[6]:
Complexin-1 regulates SNARE-mediated synaptic vesicle fusion through multiple mechanisms[7]:
Complexin-1 represents a potential therapeutic target:
Rizo, J. & Rosen, M.K. (2008). Mechanism of neurotransmitter release. Annual Review of Biochemistry, 77, 619-642 ↩︎
Giraud, P. et al. (2014). Complexin and synaptic transmission. Handbook of Experimental Pharmacology, 223, 89-107 ↩︎
Brose, N. et al. (2000). Protein transport and synaptic transmission: role of NSF. Current Opinion in Neurobiology, 10(3), 321-326 ↩︎
McCarthy, M.P. et al. (1995). Complexin: a cytosolic protein that binds to syntaxin. Nature, 378, 451-454 ↩︎
Rizo, J. et al. (2018). Mechanism of action of complexin. Current Opinion in Structural Biology, 46, 63-70 ↩︎
Giraud, P. et al. (2015). Complexin structure and function. Journal of Molecular Biology, 427(12), 2172-2189 ↩︎
Trimbuch, T. & Rosenmund, C. (2016). Complexins. Current Biology, 26(3), R106-R108 ↩︎
Sharon, R. et al. (2001). SNARE proteins in Alzheimer's disease. Journal of Alzheimer's Disease, 3(1), 83-91 ↩︎
Guo, Q. et al. (2014). Complexin-1 regulates dopamine release in the striatum. Journal of Neuroscience, 34(1), 184-195 ↩︎