Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2011 Apr;21(2):225-30.
doi: 10.1016/j.gde.2011.01.013. Epub 2011 Feb 15.

Function and regulation of the Mediator complex

Ronald C Conaway  1 , Joan Weliky Conaway
Affiliations
Review

Function and regulation of the Mediator complex

Ronald C Conaway et al. Curr Opin Genet Dev. 2011 Apr.

Abstract

Over the past few years, advances in biochemical and genetic studies of the structure and function of the Mediator complex have shed new light on its subunit architecture and its mechanism of action in transcription by RNA polymerase II (pol II). The development of improved methods for reconstitution of recombinant Mediator subassemblies is enabling more in-depth analyses of basic features of the mechanisms by which Mediator interacts with and controls the activity of pol II and the general initiation factors. The discovery and characterization of multiple, functionally distinct forms of Mediator characterized by the presence or absence of the Cdk8 kinase module have led to new insights into how Mediator functions in both Pol II transcription activation and repression. Finally, progress in studies of the mechanisms by which the transcriptional activation domains (ADs) of DNA binding transcription factors target Mediator have brought to light unexpected complexities in the way Mediator participates in signal transduction.

PubMed Disclaimer

Figures

Fig. 1
Fig. 1. Multiple Forms of Mediator
Biochemical and EM structural studies have revealed that Mediator is present in cells in at least three forms: a Mediator core, which is composed of more than twenty subunits arranged in three modules referred to as head, middle, and tail; a holoenzyme, in which the Mediator core adopts a more open conformation that encircles and binds tightly to pol II; and a third form, in which the kinase module binds to the Mediator core in a manner that precludes Mediator binding to pol II. Understanding molecular mechanisms by which each form of Mediator contributes to transcriptional activation and repression, as well as the biochemical pathways leading to the assembly and possible interconversion of the different forms of Mediator, are key challenges for future investigations of the role Mediator plays in regulating gene expression.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Myers LC, Kornberg RD. Mediator of Transcriptional Regulation. Annu Rev Biochem. 2000;69:729–749. - PubMed
    1. Backstrom S, Elfving N, Nilsson R, Wingsle G, Bjorklund S. Purification of a plant mediator from Arabidopsis thaliana identifies PFT1 as the Med25 subunit. Mol Cell. 2007;26:717–729. - PubMed

    2. This paper describes the first purification and characterization of Mediator from plants. The authors' findings illustrate the remarkable evolutionary conservation of plant and animal Mediator complexes.

    1. Sato S, Tomomori-Sato C, Parmely TJ, Florens L, Zybailov B, Swanson SK, Banks CA, Jin J, Cai Y, Washburn MP, Conaway JW, Conaway RC. A set of consensus mammalian mediator subunits identified by multidimensional protein identification technology. Mol Cell. 2004;14:685–691. - PubMed
    1. Bourbon HM. Comparative genomics supports a deep evolutionary origin for the large, four-module transcriptional mediator complex. Nucleic Acids Res. 2008;36:3993–4008. - PMC - PubMed

    2. This paper provides an in-depth bioinformatic comparison of Mediator subunits across species. The author's findings reveal the evolutionary conservation and ancient origin of Mediator in eukaryotes.

    1. Malik S, Roeder RG. Dynamic regulation of pol II transcription by the mammalian Mediator complex. Trends Biochem Sci. 2005;30:256–263. - PubMed

Publication types

LinkOut - more resources

-