Novel Mediator proteins of the small Mediator complex in Drosophila SL2 cells.
The Mediator complex is generally required for transcriptional regulation in species ranging from yeast to human. Throughout evolution, the functional diversity of the Mediator complex has been enhanced to meet the increasing requirements for sophisticated gene regulation. It is likely that greater structural complexity is thus required to accomplish these new, complex regulatory functions. In this study, we took systematic steps to examine various types of Mediator complexes in Drosophila melanogaster. Such efforts led to the identification of three distinct forms of Mediator complexes. In exploring their compositional and functional heterogeneity, we found that the smallest complex (C1) is highly enriched in a certain type of Drosophila cells and possesses novel Mediator proteins. The subunits shared among the three Mediator complexes (C1, C2, and C3) appear to form a stable modular structure that serves as a binding surface for transcriptional activator proteins. However, only C2 and C3 were able to support activated transcription in vitro. These findings suggest that different cell types may require distinct Mediator complexes, some of which may participate in nuclear processes other than the previously identified functions.
Gu
Ji-Young
JY
National Creative Research Initiative Center for Genome Regulation, Department of Biochemistry, Yonsei University, Seoul 120-749, Korea.
Park
Jin Mo
JM
Song
Eun Joo
EJ
Mizuguchi
Gaku
G
Yoon
Jeong Ho
JH
Kim-Ha
Jeongsil
J
Lee
Kong-Joo
KJ
Kim
Young-Joon
YJ
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002850:Chromatography, Gel; D016895:Culture Media, Serum-Free; D004331:Drosophila melanogaster; D004591:Electrophoresis, Polyacrylamide Gel; D008156:Luciferases / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding; D012313:RNA / Q000378:metabolism; D012330:RNA, Double-Stranded; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D016895:Culture Media, Serum-Free; D012330:RNA, Double-Stranded; D014157:Transcription Factors; D012313:RNA; D008156:Luciferases