Structure/activity elements of the multifunctional protein, GMEB-1. Characterization of domains relevant for the modulation of glucocorticoid receptor transactivation properties.
GMEB-1 was initially described as a component of a 550-kDa heteromeric DNA binding complex that is involved in the modulation of two properties of glucocorticoid receptor (GR) transactivation, the dose-response curve of agonists and the partial agonist activity of antagonists. Subsequently, GMEB-1 was also found to bind to hsp27, to associate with the coactivator TIF2 in yeast cells, and to participate in Parvovirus replication. To understand these multiple activities of GMEB-1 at a molecular level, we have now determined which regions are associated with the various activities associated with the modulation of GR transactivation properties. These activities include, homooligomerization, heterooligomerization, DNA binding, binding to GR and the transcriptional cofactor CBP, and GR modulation. Complex activities such as DNA binding and GR modulation, are found to require the physical combination of those domains that would be predicted from the involved biochemical processes. We have previously documented that GMEB-1 possesses both GR modulatory and intrinsic transactivation activity. However, the domains for these two activities of GMEB-1 are found not to overlap. This separation of activities provides a structural basis for our prior biological observations that the modulation of the dose-response curve and partial agonist activity of GR complexes is independent of the total levels of gene activation by the same GR complexes.
Chen
Jun
J
Steroid Hormones Section, NIDDK/Laboratory of Molecular and Cellular Biology, National Institutes of Health, Bethesda, Maryland 20892.
Kaul
Sunil
S
Simons
S Stoney
SS
D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002460:Cell Line; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D005982:Glutathione Transferase / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D008954:Models, Biological; D051958:Nuclear Receptor Coactivator 2; D017992:Parvovirus / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011965:Receptors, Glucocorticoid / Q000737:chemistry*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism; D015533:Transcriptional Activation; D014162:Transfection; D020798:Two-Hybrid System Techniques
D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; D051958:Nuclear Receptor Coactivator 2; D011965:Receptors, Glucocorticoid; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C400298:p96 subunit, parvovirus initiation factor; D004247:DNA; D008156:Luciferases; D005982:Glutathione Transferase