Dehydrogenase/reductase SDR family member 4（DHRS4) is a member of the short-chain dehydrogenases/reductases（SDR) family. DHRS4 reduces all trans retinal and 9-cis retinal. In addition， the DHRS4 protein can catalyze the oxidation of all trans retinol with NADP as cofactor， but with a much lower efficiency. Furthermore， DHRS4 reduces alkyl phenyl ketones and alpha dicarbonyl compounds with aromatic rings， such as pyrimidine 4 aldehyde， 3 benzoylpyridine， 4 benzoylpyridine， menadione and 4 hexanoylpyridine.
