NAD+-dependent 15-hydroxy PGDH catalyzes the oxidation of prostaglandins to 15-keto metabolites, which have greatly reduced biological activity. Human NAD+-dependent 15-hydroxy PGDH is a 266 amino acid protein with a molecular weight of 29 kDa and is expressed in multiple tissues including lung, placenta, and kidney. The enzyme belongs to a large family of short-chain alcohol dehydrogenases, which exhibit amino acid identity ranging from 15-30%. An NADP+-dependent 15-hydroxy PGDH, which is also part of this enzyme family, exhibits only 20% amino acid identity to the NAD+-dependent enzyme. The peptide used as the antigen for preparation of the 15-hydroxy PGDH antibody is highly conserved across several species -see above), but has only minor homology to other proteins within the short-chain alcohol dehydrogenase family of enzymes -only the alanine and glycine at the N-terminus of the sequence appear to be conserved).