cytochrome P450 family 4, subfamily V, and similar cytochrome P450sThis group is composed of vertebrate cytochrome P450 family 4, subfamily V (CYP4V) enzymes and similar proteins, including invertebrate subfamily C (CYP4C). Insect CYP4C enzymes may be involved in the metabolism of insect hormones and in the breakdown of synthetic insecticides. CYP4V2, the most characterized member of the CYP4V subfamily, is a selective omega-hydroxylase of saturated, medium-chain fatty acids, such as laurate, myristate and palmitate, with high catalytic efficiency toward myristate. Polymorphisms in the CYP4V2 gene cause Bietti's crystalline corneoretinal dystrophy (BCD), a recessive degenerative retinopathy that is characterized clinically by a progressive decline in central vision, night blindness, and constriction of the visual field. The CYP4V-like group belongs to the large cytochrome P450 (P450, CYP) superfamily of heme-containing proteins that catalyze a variety of oxidative reactions of a large number of structurally different endogenous and exogenous compounds in organisms from all major domains of life. CYPs bind their diverse ligands in a buried, hydrophobic active site, which is accessed through a substrate access channel formed by two flexible helices and their connecting loop.