Biosynthetic pathway of ecdysteroids.

<p>From cholesterol to 20-hydroxyecdysone, the active steroid hormone. Characterized steps: <i>Nvd, neverland</i>, Rieske-domain oxygenase; <i>Phm, Phantom</i>, CYP306A1, 25-hydroxylase; <i>Dib, Disembodied</i>, CYP302A1, 22-hydroxylase; <i>Sad, Shadow</i>, CYP315A1, 2-hydroxylase; <i>Shd, Shade</i>, CYP314A1, 20-hydroxylase. Chemical modifications are shown in red on molecules. Putative steps of the “black box”, from 7-dehydro-cholesterol to 5ß-ketodiol, are represented within the dark grey box. [O] indicates oxidative step that might be catalyzed by a CYP enzyme. Some steps could be catalyzed by shroud, spook (CYP307A1) or spookier (CYP307A2). 5ßR: 5ß-reductase. 3ßHSD: 3ß-hydroxysteroid-dehydrogenase. Modified from Lafont <i>et al. </i><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0079861#pone.0079861-Lafont1" target="_blank">[4]</a>.