Human Sterol 26-hydroxylase, Mitochondrial, CYP27A1 ELI

Cytochrome P450 monooxygenase that catalyzes regio- and stereospecific hydroxylation of cholesterol and its derivatives.

Hydroxylates (with R stereochemistry) the terminal methyl group of cholesterol side-chain in a three step reaction to yield at first a C26 alcohol, then a C26 aldehyde and finally a C26 acid (PubMed: 9660774, PubMed: 12077124, PubMed: 21411718, PubMed: 28190002).

Regulates cholesterol homeostasis by catalyzing the conversion of excess cholesterol to bile acids via both the 'neutral' (classic) and the 'acid' (alternative) pathways (PubMed: 9660774, PubMed: 1708392, PubMed: 11412116, PubMed: 2019602, PubMed: 7915755, PubMed: 9186905, PubMed: 9790667).

May also regulate cholesterol homeostasis via generation of active oxysterols, which act as ligands for NR1H2 and NR1H3 nuclear receptors, modulating the transcription of genes involved in lipid metabolism (PubMed: 9660774, PubMed: 12077124).

Plays a role in cholestanol metabolism in the cerebellum.

Similarly to cholesterol, hydroxylates cholestanol and may facilitate sterol diffusion through the blood-brain barrier to the systemic circulation for further degradation (PubMed: 28190002).

Also hydroxylates retinal 7-ketocholesterol, a noxious oxysterol with pro-inflammatory and pro-apoptotic effects, and may play a role in its elimination from the retinal pigment epithelium (PubMed: 21411718).

May play a redundant role in vitamin D biosynthesis.

Catalyzes 25-hydroxylation of vitamin D3 that is required for its conversion to a functionally active form (PubMed: 15465040).