Complexin-4 (CPLX4)

Complexin-4 is a small neuronal cytoplasmic protein that binds with high specificity to the ternary SNARE protein complex, regulating synaptic vesicle exocytosis and neurotransmitter release[1][7]. Uniquely, Complexin-4 (CPLX4) is predominantly expressed in **retinal ribbon synapses**, especially at rod synaptic terminals and co-expressed with Complexin-3 in cones[2][4]. Its functions include both inhibition (fusion clamping to prevent spontaneous vesicle release) and facilitation (promotion of evoked vesicle fusion in response to synaptic activity) of synaptic vesicle fusion, depending on conformational and contextual cues[1][2]. Unlike Complexins 1 and 2, which act in conventional CNS synapses, Complexins 3 and 4 mainly regulate visual signal transmission and plasticity in the retina by maintaining efficient neurotransmitter release. Loss of Complexin-4 (along with Complexin-3) leads to structural and functional defects in retinal synapses, resulting in visual processing deficits[2][4]. There is currently no documentation of direct therapeutic targeting, interacting drugs, or established biomarkers for CPLX4.

Other names

Complexin-4CPLX4CPX IVCPX-IVComplexin IVCPXIVcomplexin-4complexin IVsynaphin-4