Editing Steroid (section)

=== Fungal ===
Fungal steroids include the [[ergosterol]]s, which are involved in maintaining the integrity of the fungal cellular membrane. Various [[antifungal drugs]], such as [[amphotericin B]] and [[azole antifungals]], utilize this information to kill [[pathogenic]] fungi.<ref name="Bhetariya-2017">{{cite book | vauthors = Bhetariya PJ, Sharma N, Singh P, Tripathi P, Upadhyay SK, Gautam P | veditors = Arora C, Sajid A, Kalia V  | title=Drug Resistance in Bacteria, Fungi, Malaria, and Cancer|publisher=Springer|isbn=978-3-319-48683-3|language=en|chapter=Human Fungal Pathogens and Drug Resistance Against Azole Drugs| date = 21 March 2017}}</ref> Fungi can alter their ergosterol content (e.g. through loss of function mutations in the enzymes [[C-5 sterol desaturase|ERG3]] or [[Sterol 24-C-methyltransferase|ERG6]], inducing depletion of ergosterol, or mutations that decrease the ergosterol content) to develop resistance to drugs that target ergosterol.<ref name="Kavanagh Fungi" />

Ergosterol is analogous to the [[cholesterol]] found in the cellular membranes of animals (including humans), or the [[phytosterols]] found in the cellular membranes of plants.<ref name="Kavanagh Fungi">{{cite book| veditors = Kavanagh K |title=Fungi: Biology and Applications|date=8 September 2017|publisher=John Wiley & Sons, Inc.|isbn=978-1-119-37431-2|language=en}}</ref> All mushrooms contain large quantities of ergosterol, in the range of tens to hundreds of milligrams per 100 grams of dry weight.<ref name="Kavanagh Fungi" /> Oxygen is necessary for the synthesis of [[ergosterol]] in fungi.<ref name="Kavanagh Fungi" />

Ergosterol is responsible for the [[vitamin D]] content found in mushrooms; ergosterol is chemically converted into provitamin D2 by exposure to [[ultraviolet light]].<ref name="Kavanagh Fungi" /> Provitamin D2 spontaneously forms vitamin D2.<ref name="Kavanagh Fungi" /> However, not all fungi utilize ergosterol in their cellular membranes; for example, the pathogenic fungal species ''[[Pneumocystis jirovecii]]'' does not, which has important clinical implications (given the mechanism of action of many antifungal drugs). Using the fungus ''[[Saccharomyces cerevisiae]]'' as an example, other major steroids include [[ergosta‐5,7,22,24(28)‐tetraen‐3β‐ol]], [[zymosterol]], and [[lanosterol]]. ''S. cerevisiae'' utilizes [[5,6‐dihydroergosterol]] in place of ergosterol in its cell membrane.<ref name="Kavanagh Fungi" />