OPN1LW

Opsin 1, long-wave-sensitive (OPN1LW) encodes the red cone photopigment, a G protein-coupled receptor (GPCR) expressed in retinal cone cells. Aliases include red-sensitive opsin and LWS opsin. It mediates phototransduction: upon red light absorption, it activates transducin, triggering phosphodiesterase activity that reduces cyclic GMP levels. This closes cation channels, hyperpolarizing cones and initiating visual signal transmission to the brain.
Mutations in OPN1LW cause X-linked red-green color deficiencies (protanopia or protanomaly). Current therapeutic efforts focus on gene therapy—AAV-mediated delivery of functional OPN1LW restores red light detection in preclinical models, with early-phase clinical trials underway to evaluate safety and efficacy in affected individuals.