antibiotic target fungal ergosterol synthesis pathway enzyme ARO:3009195 antibiotic_resistance Ergosterol is an essential cell membrane mycosterol unique to fungi and some protozoa, and functionally analogous to cholesterol in animals. The ergosterol synthesis pathway in fungi is a common target for antifungal drugs, where ergosterol is either disrupted directly (as with amphotericin) or ergosterol synthesis is prevented at an earlier step (as with azole antibiotics inhibiting demethylation of lanosterol). In either case this results in cell death. Mutations in this enzymes may inhibit antifungal action, thereby conferring resistance to these compounds.