Retinaldehyde-binding protein 1 (Cellular retinaldehyde-binding protein) (RLBP1)

Retinaldehyde-binding protein 1 (RLBP1), also known as cellular retinaldehyde-binding protein (CRALBP), is a 36 kDa soluble protein abundantly expressed in the retinal pigment epithelium (RPE), Müller cells, and photoreceptors, where it functions as a carrier for retinoids such as 11-cis-retinal and 11-cis-retinol. It plays a critical role in the visual cycle by facilitating the regeneration of light-sensitive 11-cis-retinal from all-trans-retinal products of rhodopsin photocycle, enabling proper rod and cone photoreceptor function. CRALBP binds retinoids stereoselectively in a hydrophobic pocket, promoting their transport, enzymatic isomerization, and delivery while preventing non-specific diffusion or toxicity. Mutations disrupting retinoid binding, such as R234W or R150Q, impair visual cycle efficiency and cause autosomal recessive retinal dystrophies including retinitis pigmentosa, Bothnia dystrophy, retinitis punctata albescens, and fundus albipunctatus. The protein is also detected in brain oligodendrocytes and other tissues without endogenous retinoids, hinting at additional physiological roles. No drugs directly target CRALBP, and its study relies on recombinant models mirroring native structure and ligand interactions.

Other names

CRALBP