A mammalian homolog of Drosophila melanogaster transcriptional coactivator intersex is a subunit of the mammalian Mediator complex.
The multiprotein Mediator complex is a coactivator required for transcriptional activation of RNA polymerase II transcribed genes by DNA binding transcription factors. We previously partially purified a Med8-containing 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 of proteins present in the most highly enriched Mediator fractions by tandem mass spectrometry led to the identification of several new mammalian Mediator subunits, as well as several potential Mediator subunits. Here we identify one of these proteins, encoded by the previously uncharacterized AK000411 open reading frame, as a new subunit of the mammalian Mediator complex. The AK000411 protein, which we designate hIntersex (human Intersex), shares significant sequence similarity with the Drosophila melanogaster intersex protein, which has functional properties expected of a transcriptional coactivator specific for the Drosophila doublesex transactivator. In addition, we show that hIntersex assembles into a subcomplex with Mediator subunits p28b and TRFP. Taken together, our findings identify a new subunit of the mammalian Mediator and shed new light on the architecture of the mammalian Mediator complex.
Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA.
Shigeo
S
Sato
Chieri
C
Tomomori-Sato
Charles A S
CA
Banks
Tari J
TJ
Parmely
Irina
I
Sorokina
Christopher S
CS
Brower
Ronald C
RC
Conaway
Joan Weliky
JW
Conaway
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002845:Chromatography; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics; D029721:Drosophila Proteins / Q000737:chemistry* / Q000235:genetics; D004331:Drosophila melanogaster / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D017405:Herpes Simplex Virus Protein Vmw65 / Q000737:chemistry; D006801:Humans; D007313:Insecta; D013058:Mass Spectrometry; D056892:Mediator Complex; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012319:RNA Polymerase II / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation
D004268:DNA-Binding Proteins; C070369:DSX protein, Drosophila; D029721:Drosophila Proteins; D017405:Herpes Simplex Virus Protein Vmw65; C468125:IX protein, Drosophila; C518742:MED29 protein, human; C480227:MED8 protein, human; D056892:Mediator Complex; D011994:Recombinant Proteins; D014157:Transcription Factors; D005982:Glutathione Transferase; D012319:RNA Polymerase II