ALDH8A1 Full-Length MS Protein Standard (NP_072090), Labeled with [U- 13C6, 15N4]-L-Arginine and [U- 13C6, 15N2]-L-Lysine, was produced in human 293 cells (HEK293) with fully chemically defined cell culture medium to obtain incorporation efficiency at Creative-Proteomics. This protein belongs to the aldehyde dehydrogenases family of proteins. It plays a role in a pathway of 9-cis-retinoic acid biosynthesis in vivo. This enzyme converts 9-cis-retinal into the retinoid X receptor ligand 9-cis-retinoic acid, and has approximately 40-fold higher activity with 9-cis-retinal than with all-trans-retinal. Therefore, it is the first known aldehyde dehydrogenase to show a preference for 9-cis-retinal relative to all-trans-retinal. Three transcript variants encoding distinct protein isoforms have been identified for this gene.