Human pancreas protein 2 (PAN2) has a retinal reductase activity and is ubiquitously expressed in human tissues

Human gene for pancreas protein 2 (PAN2) is a novel member of the short-chain dehydrogenase/reductase gene superfamily. The properties of PAN2 protein have not yet been characterized. We present the first evidence that human PAN2 is a ubiquitously expressed microsomal enzyme that recognizes retinoids but not steroids as substrates with the apparent Km values between 0.08 muM and 0.4 muM. PAN2 is similar to4-fold more efficient in the reductive than in the oxidative direction. The apparent K. values for NADP(+) and NADPH are 0.65 muM and 0.32 muM versus 1200 muM and 1060 muM for NAD(+) and NADH, respectively. Kinetic constants and expression pattern of PAN2 suggest that it is likely to function as a reductase in vivo and might contribute to the reduction of retinaldehyde to retinol in most human tissues. (C) 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.