ERG3 / YLR056W Overview
- Standard Name
- Systematic Name
- SGD ID
- Feature Type
C-5 sterol desaturase; glycoprotein that catalyzes the introduction of a C-5(6) double bond into episterol, a precursor in ergosterol biosynthesis; transcriptionally down-regulated when ergosterol is in excess; mutants are viable, but cannot grow on non-fermentable carbon sources; substrate of HRD ubiquitin ligase; mutation is functionally complemented by human SC5D
- Name Description
- ERGosterol biosynthesis
- Comparative Info
The S. cerevisiae Reference Genome sequence is derived from laboratory strain
S288C. Download DNA or protein sequence, view genomic context and
coordinates. Click "Sequence Details" to view all sequence information for this locus, including that
for other strains.
Basic sequence-derived (length, molecular weight, isoelectric point) and experimentally-determined (median abundance, median absolute deviation) protein information. Click "Protein Details" for further information about the protein such as half-life, abundance, domains, domains shared with other proteins, protein sequence retrieval for various strains, physico-chemical properties, protein modification sites, and external identifiers for the protein.
- Length (a.a.)
- Mol. Weight (Da)
- Isoelectric Point
- Median Abundance (molecules/cell)
- 6462 +/- 3482
- Half-life (hr)
Curated mutant alleles for the specified gene, listed alphabetically. Click on the allele name to open the allele page. Click "SGD search" to view all alleles in search results. Click "YeastMine" to view all alleles in YeastMine.
Gene Ontology Details
GO Annotations consist of four mandatory components: a gene product, a term from one of the three
Gene Ontology (GO) controlled vocabularies
Biological Process, and
Cellular Component), a reference, and an
evidence code. SGD has manually curated and high-throughput GO Annotations, both derived from the
literature, as well as computational, or predicted, annotations. Click "Gene Ontology Details" to view
all GO information and evidence for this locus as well as biological processes it shares with other genes.
- C-5 sterol desaturase, catalyzes formation of C-5(6) double bond in episterol that yields 5,7,24(28)-ergostatrienol in third to last step of ergosterol biosynthesis pathway; integral to endoplasmic reticulum membrane
View computational annotations
- Manually Curated
- Manually Curated
- Manually Curated
Phenotype annotations for a gene are curated single mutant phenotypes that require an observable
(e.g., "cell shape"), a qualifier (e.g., "abnormal"), a mutant type (e.g., null), strain background,
and a reference. In addition, annotations are classified as classical genetics or high-throughput
(e.g., large scale survey, systematic mutation set). Whenever possible, allele information and
additional details are provided. Click "Phenotype Details" to view all phenotype annotations and
evidence for this locus as well as phenotypes it shares with other genes.
- Non-essential gene; null mutant fails to synthesize ergosterol and cannot grow on nonfermentable carbon sources; null mutant exhibits increased resistance to azole antifungal drugs and decreased resistance to various other drugs; null mutant has reduced competitive fitness in a large-scale study
Interaction annotations are curated by BioGRID and include physical
or genetic interactions observed
between at least two genes. An interaction annotation is composed of the interaction type, name of the
interactor, assay type (e.g., Two-Hybrid), annotation type (e.g., manual or high-throughput), and a
reference, as well as other experimental details. Click "Interaction Details" to view all interaction
annotations and evidence for this locus, including an interaction visualization.
2023 total interactions for 1136 unique genes
- Affinity Capture-MS: 9
- Affinity Capture-RNA: 6
- Affinity Capture-Western: 2
- PCA: 18
- Dosage Growth Defect: 1
- Dosage Rescue: 2
- Negative Genetic: 1409
- Phenotypic Enhancement: 12
- Phenotypic Suppression: 19
- Positive Genetic: 502
- Synthetic Growth Defect: 23
- Synthetic Lethality: 11
- Synthetic Rescue: 9
The number of putative Regulators (genes that regulate it) and Targets (genes it regulates) for the
given locus, based on experimental evidence. This evidence includes data generated through
high-throughput techniques. Click "Regulation Details" to view all regulation annotations, shared GO
enrichment among regulation Targets, and a regulator/target diagram for the locus.
- ERG3 encodes a C-5 sterol desaturase that participates with another desaturase Erg5p and a reductase Erg4p in the final step of ergosterol biosynthesis, the conversion of episterol to ergosterol. Ergosterol, the major sterol in fungi and the equivalent of cholesterol in mammalian cells, is an essential component of the plasma membrane, necessary for membrane integrity, fluidity, and proper function of membrane proteins. The entire sterol biosynthetic pathway occurs primarily in the endoplasmic reticulum (ER) and requires almost 30 enzymes. Activities of these enzymes have to be tightly controlled to ensure sufficient supply but also to prevent an excess accumulation of free sterols, which leads to toxicity. This regulation involves multiple mechanisms at transcriptional, translational and post-translational levels. Since sterol biosynthesis requires oxygen, under low-oxygen conditions sterol levels become low, which triggers relocation of two transcription factors, Upc2p and Ecm22p, to the nucleus. The two proteins then recognize and bind sterol regulatory elements (SRE) in the promoters of sterol biosynthesis genes and activate their transcription. Independently, oxygen levels affect transcription of sterol biosynthesis genes through a heme-dependent transcription factor Hap1p and a transcriptional repressor Rox1p. An excess of sterols, on the other hand, stimulates the ER-associated protein degradation (ERAD) pathway to remove the HMG-CoA reductase Hmg1p/Hmg2p, which catalyzes an early rate-limiting step in sterol biosynthesis, thus leading to decreased sterol production. Additionally, other components of the ergosterol pathway are also targeted for degradation by ERAD components Doa10p, Ubc7p and Cdc48p, and by another ER-associated degradation system that involves Asl1p, Asl2p and Asl3p. Despite some similarities, there are significant differences in sterol biosynthesis and its regulation between fungal and mammalian cells, which has made ergosterol biosynthesis an attractive target for antifungal drugs. Erg11p is a target of widely used azole drugs, whereas Erg1p is a target for terbinafine. Mutations in these genes are a major cause of antifungal drug resistance.
Expression data are derived from records contained in the
Gene Expression Omnibus (GEO), and are first log2
transformed and normalized. Referenced datasets may contain one or more condition(s), and as a result
there may be a greater number of conditions than datasets represented in a single clickable histogram
bar. The histogram division at 0.0 separates the down-regulated (green) conditions and datasets from
those that are up-regulated (red). Click "Expression Details" to view all expression annotations and
details for this locus, including a visualization of genes that share a similar expression pattern.
A summary of the locus, written by SGD Biocurators following a thorough review of the literature. Links
to gene names and curated GO terms are included within the Summary Paragraphs.
All manually curated literature for the specified gene, organized into topics according to their
relevance to the gene (Primary Literature, Additional Literature, or Review). Click "Literature Details"
to view all literature information for this locus, including shared literature between genes.