ASH1/YKL185W Summary Help

Standard Name ASH1 1
Systematic Name YKL185W
Feature Type ORF, Verified
Description Component of the Rpd3L histone deacetylase complex; zinc-finger inhibitor of HO transcription; mRNA is localized and translated in the distal tip of anaphase cells, resulting in accumulation of Ash1p in daughter cell nuclei and inhibition of HO expression; potential Cdc28p substrate (1, 2, 3, 4 and see Summary Paragraph)
Name Description Asymmetric Synthesis of HO 1
Chromosomal Location
ChrXI:94499 to 96265 | ORF Map | GBrowse
Gene Ontology Annotations All ASH1 GO evidence and references
  View Computational GO annotations for ASH1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Targets 71 genes
Regulators 3 genes
Classical genetics
Large-scale survey
117 total interaction(s) for 76 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 25
  • Affinity Capture-RNA: 13
  • Affinity Capture-Western: 3
  • Biochemical Activity: 8
  • Co-localization: 1
  • Protein-RNA: 20
  • Reconstituted Complex: 1

Genetic Interactions
  • Dosage Growth Defect: 1
  • Dosage Rescue: 2
  • Negative Genetic: 22
  • Phenotypic Enhancement: 2
  • Phenotypic Suppression: 3
  • Positive Genetic: 9
  • Synthetic Growth Defect: 5
  • Synthetic Rescue: 2

Expression Summary
Length (a.a.) 588
Molecular Weight (Da) 65,684
Isoelectric Point (pI) 10.72
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXI:94499 to 96265 | ORF Map | GBrowse
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1767 94499..96265 2011-02-03 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000001668

ASH1 encodes a GATA-like transcription factor that acts to specify daughter-cell fate in mating-type switching in haploid cells and in pseudohyphal growth in diploid cells deprived of nitrogen. In the context of mating-type switching, Ash1p acts to repress the transcription of HO, which encodes an endonuclease that initiates mating-type switching (1). Ash1p is required during pseudohyphal growth to activate the transcription of MUC1/FLO11, which encodes a flocculin that helps cells stick together as they grow into the substratum (5, 6).

Mating-type switching occurs only in mother cells because Ash1p prevents HO transcription in daughter cells (1). Ash1 protein is specifically localized to daughter nuclei late in the cell cycle, where it is poised to inhibit HO transcription in the following G1 (2). This asymmetric localization is achieved by the delivery of ASH1 mRNA to daughter cells by the products of the SHE genes (7, Reviewed in 8). She2p and Loc1p bind to ASH1 mRNA in mother and daughter nuclei and mediate export to the cytoplasm. She3p then associates with the ribonucleoprotein particle (mRNP) and acts as an adapter for association with the type V myosin Myo4p (also called SHE1). Myo4p transports the mRNP complex along actin cables to the bud tip. During telophase, ASH1 mRNA is anchored to the bud tip by Bni1p (also called SHE5) and/or Hek2p and/or Bud6p (9, 10, 11). Translation of ASH1 mRNA is coordinated with its transport to the bud tip such that while ASH1 is in transit, translation is delayed (12, 13).

Once in the daughter nucleus, Ash1p binds to its recognition sequences (~20 sites) in the Upstream Repression Sequence 1 (URS1) of the HO promoter. The carboxy-terminus of Ash1p contains the DNA-binding domain and the amino-terminus mediates repression of HO transcription (14). The Rpd3p histone deacetylase complex (HDAC) has been shown to contain Ash1p and bind to the HO promoter. Mutants of Rpd3p HDAC components disrupt HO repression, suggesting that chromatin architecture plays a role in regulating HO expression. Because Ash1p can function as part of an HDAC, it is likely to regulate many more genes in the genome (4).

Genes similar to ASH1 are found in ascomycetes and the Candida albicans homolog can substitute for S. cerevisiae ASH1 (15, 16).

Last updated: 2006-04-28 Contact SGD

References cited on this page View Complete Literature Guide for ASH1
1) Sil A and Herskowitz I  (1996) Identification of asymmetrically localized determinant, Ash1p, required for lineage-specific transcription of the yeast HO gene. Cell 84(5):711-22
2) Bobola N, et al.  (1996) Asymmetric accumulation of Ash1p in postanaphase nuclei depends on a myosin and restricts yeast mating-type switching to mother cells. Cell 84(5):699-709
3) Ubersax JA, et al.  (2003) Targets of the cyclin-dependent kinase Cdk1. Nature 425(6960):859-64
4) Carrozza MJ, et al.  (2005) Stable incorporation of sequence specific repressors Ash1 and Ume6 into the Rpd3L complex. Biochim Biophys Acta 1731(2):77-87; discussion 75-6
5) Chandarlapaty S and Errede B  (1998) Ash1, a daughter cell-specific protein, is required for pseudohyphal growth of Saccharomyces cerevisiae. Mol Cell Biol 18(5):2884-91
6) Pan X and Heitman J  (2000) Sok2 regulates yeast pseudohyphal differentiation via a transcription factor cascade that regulates cell-cell adhesion. Mol Cell Biol 20(22):8364-72
7) Jansen RP, et al.  (1996) Mother cell-specific HO expression in budding yeast depends on the unconventional myosin myo4p and other cytoplasmic proteins. Cell 84(5):687-97
8) Cosma MP  (2004) Daughter-specific repression of Saccharomyces cerevisiae HO: Ash1 is the commander. EMBO Rep 5(10):953-7
9) Beach DL and Bloom K  (2001) ASH1 mRNA localization in three acts. Mol Biol Cell 12(9):2567-77
10) Beach DL, et al.  (1999) Localization and anchoring of mRNA in budding yeast. Curr Biol 9(11):569-78
11) Irie K, et al.  (2002) The Khd1 protein, which has three KH RNA-binding motifs, is required for proper localization of ASH1 mRNA in yeast. EMBO J 21(5):1158-67
12) Chartrand P, et al.  (2002) Asymmetric sorting of ash1p in yeast results from inhibition of translation by localization elements in the mRNA. Mol Cell 10(6):1319-30
13) Gu W, et al.  (2004) A new yeast PUF family protein, Puf6p, represses ASH1 mRNA translation and is required for its localization. Genes Dev 18(12):1452-65
14) Maxon ME and Herskowitz I  (2001) Ash1p is a site-specific DNA-binding protein that actively represses transcription. Proc Natl Acad Sci U S A 98(4):1495-500
15) Munchow S, et al.  (2002) Characterization of Candida albicans ASH1 in Saccharomyces cerevisiae. Curr Genet 41(2):73-81
16) Inglis DO and Johnson AD  (2002) Ash1 protein, an asymmetrically localized transcriptional regulator, controls filamentous growth and virulence of Candida albicans. Mol Cell Biol 22(24):8669-80