1. A sterol found in fungi and plants that is converted to vitamin D2 when exposed to ultraviolet light.
Usage: biochemistry; also called provitamin D2

Examples

• Ergosterol is the fungal equivalent of cholesterol in animal cells.
• When mushrooms are exposed to sunlight, their ergosterol converts to vitamin D2.
• The cell membranes of yeast contain ergosterol as a key structural component.
• Some antifungal medications target ergosterol in fungal cell membranes.
• Ergosterol levels increase in plants when they are exposed to UV radiation.