Cholesterol-25-Hydroxylase (CH25H)

CH25H is an intronless gene that is involved in cholesterol and lipid metabolism. The encoded protein is a membrane protein and contains clusters of histidine residues essential for catalytic activity. Unlike most other sterol hydroxylases, this enzyme is a member of a small family of enzymes that utilize diiron cofactors to catalyze the hydroxylation of hydrophobic substrates. The deduced 272-amino acid peptide has characteristics of a polytopic membrane protein and contains clusters of histidine residues essential for catalytic activity. Northern blot analysis showed very low levels of cholesterol 25-hydroxylase mRNA in 16 different tissues. Immunohistochemistry detected cholesterol 25-hydroxylase in the endoplasmic reticulum and a perinuclear compartment of transfected cells.