Skip to main content
. Author manuscript; available in PMC: 2013 Jan 1.
Published in final edited form as: Biochim Biophys Acta. 2011 May 19;1821(1):88–98. doi: 10.1016/j.bbalip.2011.05.003

Figure 1. Retinol is as a metabolic precursor of active compounds.

Figure 1

Inside the cell, retinol (ROH), the vitamin A alcohol, is first oxidized and converted to retinal (RAL), which is known to be active in the visual cycle, even though recent data suggest that endogenous aldehydes can also control gene expression [152, 153]. Further oxidation of retinaldehyde generates retinoic acid (RA), which acts as a ligand for specific nuclear receptors, such as RAR and RXR, to regulate the transcription of a wide variety of target genes. Alternatively, ROH can also be converted to RE, which, inside the cells, represents the storage form of vitamin A. All these vitamin A derivatives are also called retinoids. The enzyme or class of enzymes catalyzing each reaction are abbreviated as follows: ADHs, alcohol dehydrogenases; RDHs, retinol dehydrogenases; Raldhs, retinal dehydrogenases; LRAT, lecithin:retinol acyltransferase; REHs, retinyl ester hydrolases.