Lathosterol is a cholesterol-like molecule found small amounts in humans. The enzyme ÃÂ7-sterol 5(6)-desaturase converts it to 7-dehydrocholesterol. It is accumulated in lathosterolosis.
The final step in the biosynthesis of lathosterol is by reduction of the double bond in the sidechain of the sterol 5ñ-cholesta-7,24-dien-3ò-ol when acted on by the enzyme ÃÂ<sup>24</sup>-sterol reductase, which uses nicotinamide adenine dinucleotide phosphate (NADPH) as its cofactor.
In vertebrates, lathosterol is an intermediate in the pathway to cholesterol via 7-dehydrocholesterol. The enzyme ÃÂ7-sterol 5(6)-desaturase catalyses the oxidation reaction:
It uses two molecules of the cofactor ferrocytochrome b<sub>5</sub> with two protons and one oxygen for each molecule of lathosterol converted.