Human reference: https://www.uniprot.org/uniprotkb/O95992/entry
Here, we report the cloning of cholesterol
25-hydroxylase cDNAs from the mouse and human. The encoded enzymes are polytopic
membrane proteins of 298 and 272 amino acids, respectively, which contain
clusters of histidine residues that are essential for catalytic activity. Unlike
most other sterol hydroxylases, cholesterol 25-hydroxylase is not a cytochrome
P450, but rather it is a member of a small family of enzymes that utilize diiron
cofactors to catalyze the hydroxylation of hydrophobic substrates. The
cholesterol 25-hydroxylase gene lacks introns, and in the human it is located on
chromosome 10q23. The murine gene is expressed at low levels in multiple
tissues. Expression of cholesterol 25-hydroxylase in transfected cells reduces
the biosynthesis of cholesterol from acetate and suppresses the cleavage of
sterol regulatory element binding protein-1 and -2. The data suggest that
cholesterol 25-hydroxylase has the capacity to play an important role in
regulating lipid metabolism by synthesizing a co-repressor that blocks sterol
regulatory element binding protein processing and ultimately leads to inhibition
of gene transcription.
The horse sequence comparison is in CH25H-bioinformatics/RESULTS.md. Transfer is assessed for this exact accession; human biochemical evidence is not equine experimental validation.