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- Mediator is a multiprotein complex that functions as a transcriptional coactivator in all eukaryotes. It was discovered in 1990 in the lab of Roger D. Kornberg, recipient of the 2006 Nobel Prize in Chemistry. Mediator complexes interact with transcription factors and RNA polymerase II. The main function of mediator complexes is to transmit signals from the transcription factors to the polymerase. Mediator complexes are variable at the evolutionary, compositional and conformational levels. The first image shows only one "snapshot" of what a particular mediator complex might be composed of, but it certainly does not accurately depict the conformation of the complex in vivo. During evolution, mediator has become more complex. The yeast Saccharomyces cerevisiae (a simple eukaryote) is thought to have up to 21 subunits in the core mediator (exclusive of the CDK module), while mammals have up to 26. Individual subunits can be absent or replaced by other subunits under different conditions. Also, there are many intrinsically disordered regions in mediator proteins, which may contribute to the conformational flexibility seen both with and without other bound proteins or protein complexes. A more realistic model of a mediator complex without the CDK module is shown in the second figure. The mediator complex is required for the successful transcription by RNA polymerase II. Mediator has been shown to make contacts with the polymerase in the transcription preinitiation complex. A recent model showing the association of the polymerase with mediator in the absence of DNA is shown in the figure to the left. In addition to RNA polymerase II, mediator must also associate with transcription factors and DNA. A model of such interactions is shown in the figure to the right. Note that the different morphologies of mediator do not necessarily mean that one of the models is correct; rather those differences may reflect the flexibility of mediator as it interacts with other molecules. For example, after binding the enhancer and core promoter, the mediator complex undergoes a compositional change in which the kinase module dissociates from the complex to allow association with RNA polymerase II and transcriptional activation. The Mediator complex is located within the cell nucleus. It is required for the successful transcription of nearly all class II gene promoters in yeast. It works in the same manner in mammals. The mediator functions as a coactivator and binds to the C-terminal domain of RNA polymerase II holoenzyme, acting as a bridge between this enzyme and transcription factors. (en)
- Mediator – substancja chemiczna wspomagająca przewodzenie impulsów, kompleks złożony z około 20 białek, który działa jako koaktywator transkrypcji u eukariontów. Białka wchodzące w skład tego kompleksu mogą wiązać się z różnymi aktywatorami transkrypcji, stabilizują wiązanie do promotora, a także oddziałują z polimerazą RNA, którą mogą fosforylować dzięki swojej aktywności kinazy. Mediatory zostały odkryte przez Rogera Kornberga. (pl)
- Mediatorkomplex är ett proteinkomplex som består av ett flertal olika subenheter. Dess funktion är att reglera transkriptionsfrekvensen av olika gener genom att föra ihop de aktiverande transkriptionsfaktorer som är bundna till enhancersekvenser nära genen. Det rekryterar även funktionella komponenter för transkription, såsom RNA-polymeraser, som behövs för att genomföra transkriptionen. (sv)
- 中介體（Mediator）舊稱DRIP或TRAP，是真核生物細胞核中啟動基因轉錄所需的蛋白質複合體，於1990年由美國生物學家罗杰·科恩伯格發現。中介體可與RNA聚合酶Ⅱ的C端結構域和轉錄因子結合，結合在基因的強化子和啟動子之間，組成轉錄前起始複合體。RNA轉錄起始後中介體和轉錄因子不會馬上自啟動子脫離，而會維持在該處以繼續結合新的RNA聚合酶Ⅱ，開啟新一輪的轉錄。 中介體的組成蛋白因物種而異，如釀酒酵母的中介體有21個核心蛋白，哺乳類的中介體則有約30個，許多中介體的蛋白具有，為結構較為彈性的區域，可能有助於其改變結構以達成不同功能，除組成的核心蛋白外，中介體還會與一些週期蛋白依賴性激酶（CDK）結合，形成轉錄前起始複合體時與中介體結合的CDK會自其脫落，使RNA聚合酶Ⅱ得以與中介體結合。中介體還會與一個非編碼RNAncRNA-a結合，與其功能有關。 除了調控mRNA（RNA聚合酶Ⅱ）的轉錄外，還有研究顯示酵母菌的中介體參與RNA聚合酶III轉錄tRNA的過程。另外中介體可能還可維持中節與端粒的結構，有些中介體的核心蛋白（、、）參與訊息傳遞路徑，可能為各種訊息傳遞路徑最終藉由影響中介體的蛋白以調控基因表現。 (zh)
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- Mediator – substancja chemiczna wspomagająca przewodzenie impulsów, kompleks złożony z około 20 białek, który działa jako koaktywator transkrypcji u eukariontów. Białka wchodzące w skład tego kompleksu mogą wiązać się z różnymi aktywatorami transkrypcji, stabilizują wiązanie do promotora, a także oddziałują z polimerazą RNA, którą mogą fosforylować dzięki swojej aktywności kinazy. Mediatory zostały odkryte przez Rogera Kornberga. (pl)
- Mediatorkomplex är ett proteinkomplex som består av ett flertal olika subenheter. Dess funktion är att reglera transkriptionsfrekvensen av olika gener genom att föra ihop de aktiverande transkriptionsfaktorer som är bundna till enhancersekvenser nära genen. Det rekryterar även funktionella komponenter för transkription, såsom RNA-polymeraser, som behövs för att genomföra transkriptionen. (sv)
- 中介體（Mediator）舊稱DRIP或TRAP，是真核生物細胞核中啟動基因轉錄所需的蛋白質複合體，於1990年由美國生物學家罗杰·科恩伯格發現。中介體可與RNA聚合酶Ⅱ的C端結構域和轉錄因子結合，結合在基因的強化子和啟動子之間，組成轉錄前起始複合體。RNA轉錄起始後中介體和轉錄因子不會馬上自啟動子脫離，而會維持在該處以繼續結合新的RNA聚合酶Ⅱ，開啟新一輪的轉錄。 中介體的組成蛋白因物種而異，如釀酒酵母的中介體有21個核心蛋白，哺乳類的中介體則有約30個，許多中介體的蛋白具有，為結構較為彈性的區域，可能有助於其改變結構以達成不同功能，除組成的核心蛋白外，中介體還會與一些週期蛋白依賴性激酶（CDK）結合，形成轉錄前起始複合體時與中介體結合的CDK會自其脫落，使RNA聚合酶Ⅱ得以與中介體結合。中介體還會與一個非編碼RNAncRNA-a結合，與其功能有關。 除了調控mRNA（RNA聚合酶Ⅱ）的轉錄外，還有研究顯示酵母菌的中介體參與RNA聚合酶III轉錄tRNA的過程。另外中介體可能還可維持中節與端粒的結構，有些中介體的核心蛋白（、、）參與訊息傳遞路徑，可能為各種訊息傳遞路徑最終藉由影響中介體的蛋白以調控基因表現。 (zh)
- Mediator is a multiprotein complex that functions as a transcriptional coactivator in all eukaryotes. It was discovered in 1990 in the lab of Roger D. Kornberg, recipient of the 2006 Nobel Prize in Chemistry. Mediator complexes interact with transcription factors and RNA polymerase II. The main function of mediator complexes is to transmit signals from the transcription factors to the polymerase. (en)
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- Mediator (coactivator) (en)
- Mediator (biologia) (pl)
- Mediatorkomplex (sv)
- 中介體 (zh)
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