Ergosterol is a sterol that is found in yeast and fungal membranes but is not present in plants or animals. It modulates the fluidity, permeability and thickness of membranes making it critical for membrane stability.1 Ergosterol that is incorporated into membranes may associate with sphingolipids in microdomains which appear to have important roles in membrane organization and function.2 Ergosterol is a useful precursor to vitamin D2 and is converted when exposed to UV irradiation. Due to its being found in yeast and fungal membranes, but not in plants or animals, ergosterol is a useful target for antifungal drugs and as a fungal biomarker.3 The fungus Agaricus blazei Murill has been recognized as having several beneficial dietary properties and ergosterol was identified as the compound responsible for its anti-tumor activity.4 Yeast uses ergosterol as an important physiological target of stress signaling.5
