all-trans Retinal is a natural retinoid that is derived from vitamin A. It is the oxidation product of all-trans retinol and associates with cellular retinol-binding protein-I (CRBP-I) and CRBP-II (Kds = 50 and 90 nM, respectively), which are involved in the intracellular transport of retinol. all-trans Retinal is also an intermediate of the phototransduction pathway of photoreceptors, including rhodopsin and bacterial opsins. As a chemically reactive aldehyde, all-trans retinal can form toxic conjugates with proteins and lipids, leading to degeneration of the retina.
