SSN8 / YNL025C Overview

Standard Name
SSN8 1
Systematic Name
GIG3 4 , NUT9 8 , CycC 9 , RYE2 , SRB11 2 , UME3 10 , CNC1 11
Feature Type
ORF , Verified
Cyclin-like component of RNA polymerase II holoenzyme; involved in phosphorylation of RNAPII C-terminal domain; forms kinase-cyclin pair in RNAPII holoenzyme with Ssn3p; needed for entry into and execution of meiotic program; involved in glucose repression, telomere maintenance; degraded in response to nitrogen starvation, and also to oxidative stress, but in different cellular compartments, and with different cellular outcomes; 35% identical to human cyclin C 2 3 4 5 6 7
Name Description
Suppressor of SNf1 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)
707 +/- 643


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 SSN8 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.

Cyclin-dependent protein serine/threonine kinase regulator subunit of the mediator complex; capable of sequence-specific RNA polymerase II core promoter binding during cellular response to heat; involved in positive and negative regulation of transcription by RNA polymerase II

View computational annotations

Cellular Component

Manually Curated


Macromolecular complex annotations are imported from the Complex Portal. These annotations have been derived from physical molecular interaction evidence extracted from the literature and cross-referenced in the entry, or by curator inference from information on homologs in closely related species or by inference from scientific background.

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 slow growth and sensitivity to heat, tacrolimus, and Zn2+; mutant has reduced survival in stationary phase; in large-scale studies, null mutant shows reduced competitive fitness, slower utilization of galactose, allantoin, and glutamate, increased telomere length, and sensitivity to heat, oxidative stress, and acid pH; null mutation in the Sigma1278b genetic background blocks invasive growth and decreases filamentous growth; null mutation confers altered resistance to a variety of 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.

540 total interactions for 402 unique genes

Physical Interactions

  • Affinity Capture-MS: 23
  • Affinity Capture-RNA: 5
  • Affinity Capture-Western: 25
  • Biochemical Activity: 3
  • Co-crystal Structure: 1
  • Co-purification: 1
  • PCA: 2
  • Reconstituted Complex: 8
  • Two-hybrid: 25

Genetic Interactions

  • Dosage Lethality: 1
  • Dosage Rescue: 9
  • Negative Genetic: 206
  • Phenotypic Enhancement: 3
  • Phenotypic Suppression: 10
  • Positive Genetic: 160
  • Synthetic Growth Defect: 31
  • Synthetic Lethality: 17
  • Synthetic Rescue: 10
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.

SSN8 (also known as SRB11) encodes a subunit of the CDK8 kinase module (CKM) of the Mediator transcriptional regulation complex. The Mediator complex is highly conserved from yeast to human, and is a central player in the transcriptional regulation of protein-coding genes, being required for nearly all transcription by RNA polymerase II (RNAPII). Mediator bridges activators and the general transcription machinery. The core Mediator complex contains three distinct head, middle, and tail modules. The CKM is a dissociable subcomplex that represses basal transcription. The other three subunits of the CKM are encoded by SSN3/CDK8/SRB10, SSN5/MED12/SRB8, and SSN2/MED13/SRB9. Formation of a Mediator-RNAPII holoenzyme is largely blocked by association of the CKM with the core Mediator complex. Interaction of the CKM with Mediator's middle module interferes with C-terminal domain (CTD)-dependent RNA polymerase II (RNAPII) binding and with the holoenzyme formation process. A combination of competitive interactions and conformational changes facilitate holoenzyme formation and underlie the mechanism of transcription regulation by Mediator. Obstruction of CTD-dependent RNAPII interaction with the middle module explains the repressive effect of the CKM on transcription.
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.

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.