Figure 1. Ergosterol model for yeast.

Solid boxes represent time dependent variables, italics represent time independent variables, consecutive arrows represent multiple enzymatic reactions taking place, and the dashed arrow indicates an inhibitory feedback signal. Blue boxes represent metabolites in common with the sphingolipid pathway from Fig. 2. Abbreviations for the time dependent variables: Palmitoyl-CoA (Pal-CoA), X₁₂; Acetyl-CoA (Ac-CoA), X₂₅; 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA), X₂₆; Mevalonate,X₂₇; Farnesyl pyrophosphate (Farnesyl-PP), X₂₈; Squalene,X₂₉; Lanosterol,X₃₀; Zymosterol,X₃₁; Endoplasmic reticulum ergosterol (Ergosterol), X₃₂; Steryl Lanosterol, X₃₃; Steryl Zymosterol, X₃₄; Steryl Ergosterol in Bulk Lipid Particles (Steryl Ergosterol-1), X ₃₅; Outer Leaflet Ergosterol in the Plasma Membrane (Ergosterol-o), X ₃₆; Detergent insoluble plasma associated ergosterol (Ergosterol-r), X ₃₇; Internal Acetate (Acetate Int.), X ₃₈; Inner Leaflet Ergosterol in the Plasma Membrane (Ergosterol-i), X ₃₉; Steryl Ergosterol in Plasma Membrane Associated Lipid Particles (Steryl Ergosterol-2), X ₄₀; Golgi Associated Complex Sphingolipids (CS-g), X ₈+X ₁₈+X ₁₉; Plasma Membrane Associated Complex Sphingolipids (CS-m), X ₂₀+X ₂₁+X ₂₂.