Phytanoyl Coenzyme A-2-Hydroxylase (PHYH)

The PHYH gene encodes phytanoyl-CoA hydroxylase, a peroxisomal protein that catalyzes the first step in the alpha-oxidation of phytanic acid, a branched-chain fatty acid. Because beta-oxidation is blocked by the methyl group at C-3, phytanic acid must first undergo decarboxylation via an alpha-oxidation mechanism catalyzed by PHYH.Both groups made use of expressed sequence tag (EST) database searching for identification of the full-length human cDNA sequence. The open reading frame encodes a 41.2-kD protein of 338 amino acids, which contains a cleavable peroxisomal targeting signal type 2 (PTS2).The structure and subcellular localization of the phytanic acid alpha-oxidation pathway long remained enigmatic, although it was generally assumed to involve phytanic acid and not its CoA-ester.