Retinol dehydrogenase 5; Catalyzes the oxidation of cis-isomers of retinol, including 11-cis-, 9-cis-, and 13-cis-retinol in an NAD-dependent manner. Has no activity towards all-trans retinal (By similarity). Plays a significant role in 11-cis retinol oxidation in the retinal pigment epithelium cells (RPE). Also recognizes steroids (androsterone, androstanediol) as its substrates. Belongs to the short-chain dehydrogenases/reductases (SDR) family.

Guanine nucleotide-binding protein G(t) subunit alpha-1; Functions as signal transducer for the rod photoreceptor RHO. Required for normal RHO-mediated light perception by the retina. Guanine nucleotide-binding proteins (G proteins) function as transducers downstream of G protein-coupled receptors (GPCRs), such as the photoreceptor RHO. The alpha chain contains the guanine nucleotide binding site and alternates between an active, GTP- bound state and an inactive, GDP-bound state. Activated RHO promotes GDP release and GTP binding. Signaling is mediated via downstream effector proteins, [...]

Retinaldehyde-binding protein 1; Soluble retinoid carrier essential the proper function of both rod and cone photoreceptors. Participates in the regeneration of active 11-cis-retinol and 11-cis-retinaldehyde, from the inactive 11- trans products of the rhodopsin photocycle and in the de novo synthesis of these retinoids from 11-trans metabolic precursors. The cycling of retinoids between photoreceptor and adjacent pigment epithelium cells is known as the 'visual cycle'.

Retinoid isomerohydrolase; Critical isomerohydrolase in the retinoid cycle involved in regeneration of 11-cis-retinal, the chromophore of rod and cone opsins. Catalyzes the cleavage and isomerization of all-trans-retinyl fatty acid esters to 11-cis-retinol which is further oxidized by 11-cis retinol dehydrogenase to 11-cis-retinal for use as visual chromophore. Essential for the production of 11-cis retinal for both rod and cone photoreceptors. Also capable of catalyzing the isomerization of lutein to meso-zeaxanthin an eye- specific carotenoid. The soluble form binds vitamin A (all-tr [...]

Guanine nucleotide-binding protein G(t) subunit alpha-2; Guanine nucleotide-binding proteins (G proteins) are involved as modulators or transducers in various transmembrane signaling systems. Transducin is an amplifier and one of the transducers of a visual impulse that performs the coupling between rhodopsin and cGMP- phosphodiesterase.

Visual pigment-like receptor peropsin; May play a role in rpe physiology either by detecting light directly or by monitoring the concentration of retinoids or other photoreceptor-derived compounds.

Rhodopsin; Photoreceptor required for image-forming vision at low light intensity. Required for photoreceptor cell viability after birth. Light- induced isomerization of the chromophore 11-cis-retinal to all-trans- retinal triggers a conformational change that activates signaling via G-proteins. Subsequent receptor phosphorylation mediates displacement of the bound G-protein alpha subunit by the arrestin SAG and terminates signaling.

Short-wave-sensitive opsin 1; Visual pigments are the light-absorbing molecules that mediate vision. They consist of an apoprotein, opsin, covalently linked to cis-retinal (Probable). Required for the maintenance of cone outer segment organization in the ventral retina, but not essential for the maintenance of functioning cone photoreceptors (By similarity). Involved in ensuring correct abundance and localization of retinal membrane proteins (By similarity). May increase spectral sensitivity in dim light (By similarity); Belongs to the G-protein coupled receptor 1 family. Opsin subfamily.

Opsin-3; May play a role in encephalic photoreception; Belongs to the G-protein coupled receptor 1 family. Opsin subfamily.