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Chromatin is composed of arrays of nucleosomes, with each nucleosome comprising an octamer formed by two copies each of the H2A-H2B and H3-H4 heterodimers (10). In Saccharomyces cerevisiae, each of the canonical histones is encoded by two genes: H2A by HTA1 and HTA2, H2B by HTB1 and HTB2, H3 by HHT1 and HHT2, and H4 by HHF1 and HHF2. The eight genes are organized into four pairs of divergently-transcribed loci: HTA1-HTB1 and HTA2-HTB2, each encoding histone proteins H2A and H2B; and HHT1-HHF1 and HHT2-HHF2, each encoding histone proteins H3 and H4. As a result of this redundancy, deletion of any one histone locus does not cause lethality (11). The H3-H4 protein dimers interact via a four-helix bundle at the H3 C-termini, and the H2A-H2B dimers bind to the resulting central H3-H4 tetramer via a similar four-helix bundle interaction between the H2B and H4 C-termini (12). Approximately 150 bp of duplex DNA is wound onto the histone octamer as two turns of a negative superhelix (13). A single copy of the linker histone H1 (encoded by HHO1) binds between the superhelices at the site of DNA entry and exit. In some nucleosomes, the histone variant H2A.Z (encoded by HTZ1) is substituted for the canonical H2A in a wide, but nonrandom, genomic distribution, enriched in promoter regions as compared to coding regions (14). The positioning of nucleosomes along chromatin has been implicated in the regulation of gene expression, since the packaging of DNA into nucleosomes affects sequence accessibility (15). Nucleosomes prevent many DNA-binding proteins from approaching their sites (16, 17, 18), whereas appropriately positioned nucleosomes can bring discontiguous DNA sequences into close proximity to promote transcription (19).", "date_edited": "2007-05-31"}, "literature_overview": {"primary_count": 408, "additional_count": 546, "review_count": 222, "go_count": 2, "phenotype_count": 11, "disease_count": 1, "interaction_count": 275, "regulation_count": 43, "ptm_count": 48, "funComplement_count": 0, "htp_count": 51, "total_count": 1330}, "disease_overview": {"manual_disease_terms": [{"annotation_type": "manually curated", "qualifiers": [null], "term": {"link": "/disease/DOID:0051010", "display_name": "Bryant-Li-Bhoj neurodevelopmental syndrome"}, "evidence_codes": [{"display_name": "ISS", "link": "http://wiki.geneontology.org/index.php/Inferred_from_Sequence_or_structural_Similarity_(ISS)"}]}], "htp_disease_terms": [], "computational_annotation_count": 0, "date_last_reviewed": "2025-04-18", "paragraph": "HHT1 and HHT2 are orthologous to human H3-3A and H3-3B and have been used to study Bryant-Li-Bhoj syndrome (BLBS)"}, "ecnumbers": [], "URS_ID": null, "main_strain": "S288C", "regulation_overview": {"regulator_count": 34, "target_count": 0}, "reference_mapping": {"371966": 1, "634771": 2, "627439": 3, "606778": 4, "595990": 5, "557337": 6, "553832": 7, "552194": 8, "550840": 9, "525910": 10, "618194": 11, "568795": 12, "501032": 13, "525380": 14, "530228": 15, "501029": 16, "501026": 17, "633866": 18, "501023": 19}, "history": [{"category": "Name", "history_type": "LSP", "note": "Name: HHT2", "date_created": "2000-05-19", "references": [{"id": 551590, "display_name": "SGD (2007)", "citation": "SGD (2007) Information without a citation in SGD ", "pubmed_id": null, "link": "/reference/S000073348", "year": 2007, "urls": []}]}], "complexes": []}, tabs: {"id": 1283785, "protein_tab": true, "interaction_tab": true, "summary_tab": true, "go_tab": true, "sequence_section": true, "expression_tab": true, "phenotype_tab": true, "literature_tab": true, "wiki_tab": false, "regulation_tab": true, "sequence_tab": true, "history_tab": true, "homology_tab": true, "disease_tab": true} }; HHT2 | SGD

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HHT2 / YNL031C Overview

Standard Name
HHT2
Systematic Name
YNL031C
SGD ID
SGD:S000004976
Feature Type
ORF , Verified
Description
Histone H3; core histone protein required for chromatin assembly, part of heterochromatin-mediated telomeric and HM silencing; one of two identical histone H3 proteins (see HHT1); regulated by acetylation, methylation, and phosphorylation; H3K14 acetylation plays an important role in the unfolding of strongly positioned nucleosomes during repair of UV damage 1 2 3 4 5 6 7 8 9
Name Description
Histone H Three
Paralog
HHT1
Comparative Info
Sequence Details

Sequence

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.

Analyze Sequence

S288C only

BLASTN | BLASTP | Design Primers | Restriction Fragment Map | Restriction Fragment Sizes | Six-Frame Translation

S288C vs. other species

BLASTN vs. fungi | BLASTP at NCBI | BLASTP at NCBI | BLASTP vs. fungi

S288C vs. other strains

Strain Alignment | Variant Viewer

Protein Details

Protein

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.)
136
Mol. Weight (Da)
15378.3
Isoelectric Point
11.99
Median Abundance (molecules/cell)
13263 +/- 9333

Alleles

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 HHT2 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.

Summary
Nucleosomal cupric reductase involved in aerobic respiration and copper ion homeostasis

View computational annotations

Molecular Function

Manually Curated

Biological Process

Manually Curated

Cellular Component

Manually Curated
Phenotype Details

Phenotype

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.

Summary
Non-essential gene, due to the presence of two identical genes, HHT1 and HHT2; conditional mutations in cells lacking HHT1 cause slow growth, heat and cold sensitivity and increased sensitivity to 6-azauracil, benomyl, bleomycin, caffeine, camptothecin, formamide and hydroxyurea

Classical Genetics

overexpression
unspecified
repressible
reduction of function
conditional
null

Large-scale Survey

null
overexpression
unspecified
Disease Details

Disease

Disease Annotations consist of three mandatory components: a gene product, a term from the Disease Ontology (DO) controlled vocabulary and an evidence code. SGD provides manually curated DO Annotations derived from the literature. Click "Disease Details" to view all Disease information and evidence for this locus as well as diseases it shares with other genes.

Summary
HHT1 and HHT2 are orthologous to human H3-3A and H3-3B and have been used to study Bryant-Li-Bhoj syndrome (BLBS)

Manually Curated

Interaction Details

Interaction

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.

1243 total interactions for 714 unique genes

Physical Interactions

  • Affinity Capture-Luminescence: 17
  • Affinity Capture-MS: 553
  • Affinity Capture-RNA: 19
  • Affinity Capture-Western: 149
  • Biochemical Activity: 51
  • Co-crystal Structure: 4
  • Co-fractionation: 1
  • Co-localization: 9
  • Co-purification: 3
  • FRET: 1
  • PCA: 11
  • Protein-peptide: 17
  • Reconstituted Complex: 89
  • Two-hybrid: 1

Genetic Interactions

  • Dosage Growth Defect: 17
  • Dosage Lethality: 1
  • Dosage Rescue: 10
  • Negative Genetic: 110
  • Phenotypic Enhancement: 20
  • Phenotypic Suppression: 36
  • Positive Genetic: 33
  • Synthetic Growth Defect: 43
  • Synthetic Lethality: 13
  • Synthetic Rescue: 35
Regulation Details

Regulation

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.

Regulators
34
Targets
0
Expression Details

Expression

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: 2007-05-31

Literature Details

Literature

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.

Primary
408
Additional
546
Reviews
222

Resources

AlphaFold Protein Structure | Entrez Gene | Entrez Gene | Entrez RefSeq Protein | Entrez RefSeq Protein | FungiDB | Search all NCBI | UniParc | UniProtKB