OPI1 / YHL020C Overview

Standard Name
OPI1 1
Systematic Name
Feature Type
ORF , Verified
Transcriptional regulator of a variety of genes; critical sensor of genotoxic stress; phosphorylation by protein kinase A stimulates Opi1p function in negative regulation of phospholipid biosynthetic genes; involved in telomere maintenance; null exhibits disrupted mitochondrial metabolism and low cardiolipin content, strongly correlated with overproduction of inositol; binds to phosphatidic acid 2 3 4 5 6 7
Name Description
OverProducer of Inositol 1
Comparative Info
Sequence Details


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.

OPI1 is located on the left arm of chromosome VIII between AIM17 and APM2 genes for proteins of unknown function; coding sequence is 1215 nucleotides long with 7 SNPs, 2 of which cause amino acid polymorphisms, and a variable repetitive region around nucleotide 900
Protein Details


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.

Opi1p is 404 amino acids long, short-lived and low in abundance; phosphorylated at 11 serines and 1 threonine, ubiquitinylated at 5 lysines
Length (a.a.)
Mol. Weight (Da)
Isoelectric Point
Median Abundance (molecules/cell)
2525 +/- 1033
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.

View all OPI1 alleles in SGD search

Gene Ontology Details

Gene Ontology

GO Annotations consist of four mandatory components: a gene product, a term from one of the three Gene Ontology (GO) controlled vocabularies (Molecular Function, 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.

Transcription corepressor and phosphatidic acid-binding protein; regulates transcription from RNA polymerase II promoters and negatively regulates phospholipid biosynthesis; involved in the endoplasmic reticulum unfolded protein response; localizes to the endoplasmic reticulum and to various components of the nucleus

View computational annotations

Molecular Function

Manually Curated

Cellular Component

Manually Curated
Phenotype Details


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 displays Opi- phenotype (overproduction and excretion of inositol in the absence of inositol and choline) and petite-negative phenotype (loss of the mitochondrial genome is lethal); null mutant has reduced growth rate on nonfermentable carbon sources and decreased survival rate in stationary phase; in large-scale studies, null mutant displays decreased competitive fitness in a variety of media and altered resistance to various chemicals
Interaction Details


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.

Interacts physically with proteins involved in translation regulation and transcription; interacts genetically with genes involved in transcription

627 total interactions for 484 unique genes

Physical Interactions

  • Affinity Capture-MS: 9
  • Affinity Capture-RNA: 6
  • Affinity Capture-Western: 8
  • Biochemical Activity: 5
  • Co-purification: 1
  • Reconstituted Complex: 10
  • Two-hybrid: 11

Genetic Interactions

  • Dosage Lethality: 1
  • Dosage Rescue: 5
  • Negative Genetic: 456
  • Phenotypic Enhancement: 5
  • Phenotypic Suppression: 6
  • Positive Genetic: 63
  • Synthetic Growth Defect: 14
  • Synthetic Lethality: 6
  • Synthetic Rescue: 21
Regulation Details


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.

OPI1 encodes a transcriptional repressor involved in regulation of phospholipid synthesis in response to the availability of inositol. Inositol is a key component of phosphatidylinositol (PI), and an essential precursor for inositol-containing sphingolipids, glycosylphosphatidylinositol (GPI) anchors, as well as signaling molecules, such as phosphoinositides and inositol polyphosphates. It also affects synthesis of phosphatidic acid (PA)-derived lipids, such as phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS). Genes involved in these pathways are positively regulated by the Ino2p/Ino4p heterodimer, which binds the inositol sensitive upstream activating elements (UAS-INO) in their promoters. Opi1p interacts with Ino2p and with general corepressors Sin3p and Ssn6p, and recruits multiple histone deacetylases, including Hda1p, Hos3p and Rpd3p, to their promoters, thus repressing transcription. The transcriptional repressor activity of Opi1p is regulated through its cellular location that responds to changing levels of PA and PI, which in turn are affected by the presence of inositol. In cells grown without exogenous inositol, PI levels are low, PA levels are high, and Opi1p remains in the perinuclear ER, where it is tethered to the membrane though association with PA and an integral membrane protein Scs2p. When inositol is added, PI synthesis rapidly increases and the ER pool of PA is depleted, which causes release of Opi1p from the membrane and its translocation to the nucleus, where it represses transcription of UAS-INO-containing promoters.
Expression Details


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.

Summary Paragraph

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.

Last Updated: 2024-06-25

Literature Details


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.