PHO4 / YFR034C Overview

Standard Name
PHO4 1
Systematic Name
phoD 9
Feature Type
ORF , Verified
Basic helix-loop-helix (bHLH) transcription factor of the myc-family; activates transcription cooperatively with Pho2p in response to phosphate limitation; binding to 'CACGTG' motif is regulated by chromatin restriction, competitive binding of Cbf1p to the same DNA binding motif and cooperation with Pho2p; function is regulated by phosphorylation at multiple sites and by phosphate availability 2 3 4 5
Name Description
PHOsphate metabolism 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.

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.

Length (a.a.)
Mol. Weight (Da)
Isoelectric Point
Median Abundance (molecules/cell)
2560 +/- 1461
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.

View all PHO4 alleles in SGD search | YeastMine

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.

Sequence specific DNA-binding RNA polymerase II transcription factor that activates expression of genes involved in the response to phosphate starvation such as PHO5; relocates to the nucleus during phosphate starvation

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 exhibits reduced acid phosphatase activity in low-inorganic phosphate medium and is resistant to quinine but sensitive to disodium selenite; overexpression causes morphological and cell cycle defects; in large-scale studies, null mutant displays a strong growth defect in low-phosphate medium, slow respiratory growth, and sensitivity to alkaline pH and anoxia
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.

352 total interactions for 262 unique genes

Physical Interactions

  • Affinity Capture-MS: 134
  • Affinity Capture-RNA: 8
  • Affinity Capture-Western: 8
  • Biochemical Activity: 24
  • Co-crystal Structure: 2
  • Co-localization: 1
  • PCA: 2
  • Protein-peptide: 1
  • Protein-RNA: 1
  • Proximity Label-MS: 1
  • Reconstituted Complex: 27
  • Two-hybrid: 11

Genetic Interactions

  • Dosage Lethality: 4
  • Dosage Rescue: 5
  • Negative Genetic: 61
  • Phenotypic Enhancement: 5
  • Phenotypic Suppression: 20
  • Positive Genetic: 22
  • Synthetic Growth Defect: 6
  • Synthetic Lethality: 1
  • Synthetic Rescue: 8
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.

PHO4 encodes a zipper-type transcription factor of the basic helix-loop-helix (bHLH) family. Pho4p binds as a homodimer to DNA containing the binding site 5'-SCACGTGS-3', which is found in the promoters of genes that are positively regulated in response to phosphate availability. Multiple phosphorylation sites on Pho4p play distinct roles in regulating its subcellular localization and its DNA binding function. The Pho80p-Pho85p kinase complex phosphorylates Pho4p on five Ser-Pro (SP) dipeptides referred to as SP1, SP2, SP3, SP4 and SP6. Sites SP2 and SP3 regulate the nuclear export of Pho4p, while site SP4 regulates the import of Pho4p. Site SP6 regulates the interaction of Pho4p with Pho2p, which is required for expression of acid phosphatase PHO5. When phosphate is abundant, Pho4p is phosphorylated by the Pho80p-Pho85p complex and exported to the cytoplasm by the receptor Msn5p where it is unable to activate transcription of phosphate-responsive genes such PHO5. When phosphate is limiting, the cyclin-dependent kinase (CDK) inhibitor Pho81p inactivates the Pho80p-Pho85p complex, leading to accumulation of unphosphorylated Pho4p in the nucleus and subsequent activation of phosphate-responsive genes.
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: 2003-03-14

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.