title: An activator target in the RNA polymerase II holoenzyme.
abstract: Expression of protein-coding genes in eukaryotes involves the recruitment, by transcriptional activator proteins, of a transcription initiation apparatus consisting of greater than 50 polypeptides. Recent genetic and biochemical evidence in yeast suggests that a subset of these proteins, called SRB proteins, are likely targets for transcriptional activators. We demonstrate here, through affinity chromatography, photo-cross-linking, and surface plasmon resonance experiments, that the GAL4 activator interacts directly with the SRB4 subunit of the RNA polymerase II holoenzyme. The GAL4 activation domain binds to two essential segments of SRB4. The physiological relevance of this interaction is confirmed by mutations in SRB4, which occur within its GAL4-binding domain and which restore activation in vivo by a GAL4 derivative bearing a mutant activation domain.
authors.affiliation: Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Koh
authors.forename: A Z
authors.initials: AZ
authors.lastname: Ansari
authors.forename: M
authors.initials: M
authors.lastname: Ptashne
authors.forename: R A
authors.initials: RA
authors.lastname: Young
mesh_terms: D001665:Binding Sites / Q000502:physiology; D015374:Biosensing Techniques; D003067:Coenzymes / Q000235:genetics / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000378:metabolism; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D056892:Mediator Complex; D009097:Multienzyme Complexes / Q000378:metabolism; D016296:Mutagenesis / Q000502:physiology; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics; D010777:Photochemistry; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins; D013057:Spectrum Analysis; D013379:Substrate Specificity; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology
chemical_list: D003067:Coenzymes; D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; D056892:Mediator Complex; D009097:Multienzyme Complexes; D010446:Peptide Fragments; C074748:SRB2 protein, S cerevisiae; C082148:SRB4 protein, S cerevisiae; C082149:SRB5 protein, S cerevisiae; C082150:SRB6 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D012319:RNA Polymerase II