Rhodopsin receptor (opsin) (RHO (gene); Rho (protein) [context-dependent])

Rhodopsin is a light-sensitive G protein-coupled receptor located in rod photoreceptor outer segment discs, formed by opsin covalently bound to the chromophore 11-cis-retinal; photon absorption triggers isomerization to all-trans-retinal, conformational change, and activation of the phototransduction cascade. The RHO gene on chromosome 3q22.1 encodes a 348–amino acid, ~39 kDa protein that constitutes the majority of rod outer segment membrane protein and is densely organized into higher-order arrays important for outer segment morphogenesis. Rhodopsin is a prototypical Class A (rhodopsin-like) GPCR and a key target in inherited retinal diseases; modulators include investigational gene therapies aimed at RHO and experimental allosteric nanobodies that stabilize specific receptor states and mitigate misfolding in disease-associated variants.

Other names

RhodopsinRod opsinVisual pigment of rodsRHO (gene symbol)

Gene modulation (AAV gene therapy) to restore or adjust RHO expression/function in retinitis pigmentosa. Allosteric modulation of rhodopsin conformational states (e.g., nanobodies stabilizing extracellular/intracellular conformations to reduce misfolding or alter activation thermodynamics). Chromophore-based inverse agonism is intrinsic: 11-cis-retinal acts as an inverse agonist stabilizing inactive rhodopsin; light-driven isomerization to all-trans-retinal activates signaling.