Back منشط (وراثة) Arabic Aktivator (Genetik) German Ενεργοποιητής (γενετική) Greek Activador (genética) Spanish راهانداز (ژنتیک) Persian Activateur (génétique) French Músclóir (bitheolaíocht) Irish Activador (xenética) Galician アクチベーター Japanese 활성인자 Korean
A transcriptional activator is a protein (transcription factor) that increases transcription of a gene or set of genes.[1] Activators are considered to have positive control over gene expression, as they function to promote gene transcription and, in some cases, are required for the transcription of genes to occur.[1][2][3][4] Most activators are DNA-binding proteins that bind to enhancers or promoter-proximal elements.[1] The DNA site bound by the activator is referred to as an "activator-binding site".[3] The part of the activator that makes protein–protein interactions with the general transcription machinery is referred to as an "activating region" or "activation domain".[1]
Most activators function by binding sequence-specifically to a regulatory DNA site located near a promoter and making protein–protein interactions with the general transcription machinery (RNA polymerase and general transcription factors), thereby facilitating the binding of the general transcription machinery to the promoter.[1][2][3][4] Other activators help promote gene transcription by triggering RNA polymerase to release from the promoter and proceed along the DNA.[2] At times, RNA polymerase can pause shortly after leaving the promoter; activators also function to allow these "stalled" RNA polymerases to continue transcription.[1][2]
The activity of activators can be regulated. Some activators have an allosteric site and can only function when a certain molecule binds to this site, essentially turning the activator on.[4] Post-translational modifications to activators can also regulate activity, increasing or decreasing activity depending on the type of modification and activator being modified.[1]
In some cells, usually eukaryotes, multiple activators can bind to the binding-site; these activators tend to bind cooperatively and interact synergistically.[1][2]
- ^ a b c d e f g h Ma, Jun (2011). "Transcriptional activators and activation mechanisms". Protein & Cell. 2 (11): 879–888. doi:10.1007/s13238-011-1101-7. ISSN 1674-8018. PMC 4712173. PMID 22180087.
- ^ a b c d e Alberts, Bruce; Johnson, Alexander; Lewis, Julian; Morgan, David; Raff, Martin; Roberts, Keith; Walter, Peter (2015). Molecular Biology of the Cell (Sixth ed.). New York, NY: Garland Science. pp. 373–392. ISBN 978-0-8153-4432-2. OCLC 887605755.
- ^ a b c Madigan, Michael T; Bender, Kelly S; Buckley, Daniel H; Sattley, Matthew W; Stahl, David A (2018). Brock Biology of Microorganisms (Fifteenth ed.). NY, NY: Pearson. pp. 174–179. ISBN 978-0-13-426192-8. OCLC 958205447.
- ^ a b c Griffiths, Anthony J.F.; Gelbart, William M.; Miller, Jeffrey H.; Lewontin, Richard C. (1999). "The Basics of Prokaryotic Transcriptional Regulation". Modern Genetic Analysis – via NCBI.