FIG. 1.—
Vertebrate retinoid (A) and steroid (B) metabolism. (A) The main components of retinoid metabolism, storage, and transport in vertebrates are shown. Proteins are boxed, and retinoids are in black. Proteins of the same family are shown in identical colors. Enzymatic reactions are shown with arrows. The dotted arrow indicates retinoid transport and dotted lines highlight retinoid binding to proteins. (B) The main enzymatic reactions of steroidogenesis in vertebrates are indicated. Enzymatic reactions are shown with arrows. Proteins are boxed, and steroids are in black. Proteins of the same family are shown in identical colors.