A mammalian mediator subunit that shares properties with Saccharomyces cerevisiae mediator subunit Cse2.
The multiprotein Mediator complex is a coactivator required for activation of RNA polymerase II transcription by DNA bound transcription factors. We previously identified and partially purified a mammalian Mediator complex from rat liver nuclei (Brower, C.S., Sato, S., Tomomori-Sato, C., Kamura, T., Pause, A., Stearman, R., Klausner, R.D., Malik, S., Lane, W.S., Sorokina, I., Roeder, R.G., Conaway, J.W., and Conaway, R.C. (2002) Proc. Natl. Acad. Sci. U. S. A. 99, 10353-10358). Analysis by tandem mass spectrometry of proteins present in the most highly purified rat Mediator fractions led to the identification of a collection of new mammalian Mediator subunits, as well as several potential Mediator subunits including a previously uncharacterized protein encoded by the FLJ10193 open reading frame. In this study, we present direct biochemical evidence that the FLJ10193 protein, which we designate Med25, is a bona fide subunit of the mammalian Mediator complex. In addition, we present evidence that Med25 shares structural and functional properties with Saccharomyces cerevisiae Mediator subunit Cse2 and may be a mammalian Cse2 ortholog. Taken together, our findings identify a novel mammalian Mediator subunit and shed new light on the architecture of the mammalian Mediator complex.
Tomomori-Sato
Chieri
C
Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA.
Sato
Shigeo
S
Parmely
Tari J
TJ
Banks
Charles A S
CA
Sorokina
Irina
I
Florens
Laurence
L
Zybailov
Boris
B
Washburn
Michael P
MP
Brower
Christopher S
CS
Conaway
Ronald C
RC
Conaway
Joan Weliky
JW
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002845:Chromatography; D004591:Electrophoresis, Polyacrylamide Gel; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007313:Insecta; D008099:Liver / Q000378:metabolism; D046911:Macromolecular Substances; D013058:Mass Spectrometry; D056892:Mediator Complex; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D016366:Open Reading Frames; D017434:Protein Structure, Tertiary; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism; D014158:Transcription, Genetic
C082275:CSE2 protein, S cerevisiae; D002352:Carrier Proteins; C483045:MED25 protein, human; D046911:Macromolecular Substances; D056892:Mediator Complex; D046912:Multiprotein Complexes; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D005982:Glutathione Transferase