HSD17B4
D-bifunctional protein, also known as peroxisomal multifunctional enzyme type 2, as well as 17β-hydroxysteroid dehydrogenase type IV is a protein that in humans is encoded by the HSD17B4 gene. It's an alcohol oxidoreductase, specifically 17β-Hydroxysteroid dehydrogenase. It is involved in fatty acid β-oxidation and steroid metabolism.Function
The HSD17B4 gene encodes an enzyme involved in peroxisomal fatty acid beta-oxidation. It was first identified as a 17-beta-estradiol dehydrogenase. Peroxisomal beta-oxidation of fatty acids, originally described by Lazarow and de Duve, is catalyzed by 3 enzymes: acyl-CoA oxidase ; the 'D-bifunctional enzyme,' with enoyl-CoA hydratase and D-3-hydroxyacyl-CoA dehydrogenase activity, and 3-ketoacyl-CoA thiolase.
See also the L-bifunctional peroxisomal protein. The D- and L-bifunctional proteins have different substrate specificities. The D-bifunctional protein catalyzes the formation of 3-ketoacyl-CoA intermediates from both straight-chain and 2-methyl-branched-chain fatty acids and also acts in shortening cholesterol for bile acid formation. In contrast, the L-specific bifunctional protein does not have the latter 2 activities.
