Structure/activity relationships for GMEB-2: the second member of the glucocorticoid modulatory element-binding complex.
The position of the dose-response curve of agonist complexes of glucocorticoid receptors (GRs), and the partial agonist activity of GR-antagonist complexes, can be modulated by two proteins (GMEB-1 and -2), which bind as oligomers to a DNA element that is called a glucocorticoid modulatory element, or GME. This element is active when located upstream of the glucocorticoid response element that controls the expression of a reporter gene. Here, we report the structure/activity relationships of GMEB-2 and compare them to our previous findings for GMEB-1. Most of the activities of GMEB-2, such as homo- and heterooligomerization, binding to GR and to CBP, DNA binding, and modulation of the above GR transcriptional properties, require large regions of the protein. Only the intrinsic transactivation activity could be localized to a small region of the protein. These studies shed light on the mechanism of action of GMEB-2 and further support our previous conclusion that the ability of factors to modulate the position of the dose-response curve, and the partial agonist activity, of GR complexes is unrelated to effects on the total levels of GR-induced gene expression. These studies also identify regions of GMEB-2 possessing yet unidentified properties that are critical for several activities. Finally, as the domain organization of GMEB-2 and -1 is extremely similar, we conclude that the quantitative differences in activities derive from variations in amino acid sequence rather than more global features of protein structure.
Chen
Jun
J
Steroid Hormones Section, NIDDK/LMCB, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, MD, USA.
He
Yuanzheng
Y
Simons
S Stoney
SS
D000818:Animals; D019556:COS Cells; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005822:Genetic Vectors; D006801:Humans; D046911:Macromolecular Substances; D008970:Molecular Weight; D039502:Nuclear Cap-Binding Protein Complex / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D051381:Rats; D011965:Receptors, Glucocorticoid / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D014162:Transfection; D044763:Ubiquitin-Conjugating Enzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000098843:Ubiquitin-Conjugating Enzyme UBC9
D004268:DNA-Binding Proteins; C490664:GMEB1 protein, human; C490663:GMEB2 protein, human; C490662:Gmeb2 protein, mouse; C490661:Gmeb2 protein, rat; D046911:Macromolecular Substances; D039502:Nuclear Cap-Binding Protein Complex; D011965:Receptors, Glucocorticoid; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C400299:p79 subunit, parvovirus initiation factor; D044763:Ubiquitin-Conjugating Enzymes; D000098843:Ubiquitin-Conjugating Enzyme UBC9