ERG3
{{Infobox nonhuman protein
| Name = Sterol C-5 desaturase
| image =
| width =
| caption =
| Organism = Saccharomyces cerevisiae
| TaxID = 4932
| Symbol = ERG3
| AltSymbols = SC5D, SYR1
| EntrezGene = 850745
| HomoloGene = 5044
| PDB =
| RefSeqmRNA = NM_001181943
| RefSeqProtein =
| UniProt =
| ECnumber = 1.14.19.20
| Chromosome = XII
| EntrezChromosome =
| GenLoc_start = 253861
| GenLoc_end = 254958
}}
ERG3 or sterol C-5 desaturase is a fungal enzyme originally from Saccharomyces cerevisiae, the human ortholog of ERG3 is SC5D.{{cite journal | vauthors = Hemmi K, Julmanop C, Hirata D, Tsuchiya E, Takemoto JY, Miyakawa T | title = The physiological roles of membrane ergosterol as revealed by the phenotypes of syr1/erg3 null mutant of Saccharomyces cerevisiae | journal = Bioscience, Biotechnology, and Biochemistry | volume = 59 | issue = 3 | pages = 482–6 | date = March 1995 | pmid = 7766188 | doi = 10.1271/BBB.59.482 | doi-access = }} ERG3 localizes to both the endoplasmic reticulum and vesicles,{{cite journal | vauthors = Natter K, Leitner P, Faschinger A, Wolinski H, McCraith S, Fields S, Kohlwein SD | title = The spatial organization of lipid synthesis in the yeast Saccharomyces cerevisiae derived from large scale green fluorescent protein tagging and high resolution microscopy | journal = Molecular & Cellular Proteomics | volume = 4 | issue = 5 | pages = 662–72 | date = May 2005 | pmid = 15716577 | doi = 10.1074/mcp.M400123-MCP200 | doi-access = free }}{{cite journal | vauthors = Poklepovich TJ, Rinaldi MA, Tomazic ML, Favale NO, Turkewitz AP, Nudel CB, Nusblat AD | title = The cytochrome b5 dependent C-5(6) sterol desaturase DES5A from the endoplasmic reticulum of Tetrahymena thermophila complements ergosterol biosynthesis mutants in Saccharomyces cerevisiae | journal = Steroids | volume = 77 | issue = 13 | pages = 1313–20 | date = November 2012 | pmid = 22982564 | pmc = 3501532 | doi = 10.1016/j.steroids.2012.08.015 }} catalyzes the C5(6)-dehydrogenation of episterol to 5-dehydroepisterol, 5-Dehydroepisterol will be further converted into ergosterol.{{cite journal | vauthors = Brumfield KM, Moroney JV, Moore TS, Simms TA, Donze D | title = Functional characterization of the Chlamydomonas reinhardtii ERG3 ortholog, a gene involved in the biosynthesis of ergosterol | journal = PLOS ONE | volume = 5 | issue = 1 | pages = e8659 | date = January 2010 | pmid = 20084111 | doi = 10.1371/journal.pone.0008659 | pmc = 2799552 | bibcode = 2010PLoSO...5.8659B | doi-access = free }}{{cite journal | vauthors = Miyazaki T, Miyazaki Y, Izumikawa K, Kakeya H, Miyakoshi S, Bennett JE, Kohno S | title = Fluconazole treatment is effective against a Candida albicans erg3/erg3 mutant in vivo despite in vitro resistance | journal = Antimicrobial Agents and Chemotherapy | volume = 50 | issue = 2 | pages = 580–6 | date = February 2006 | pmid = 16436713 | doi = 10.1128/AAC.50.2.580-586.2006 | pmc = 1366932 }}