Histone binding protein RbAp48 interacts with a complex of CREB binding protein and phosphorylated CREB.
A CREB-CREB binding protein (CBP) complex was used as bait to screen a mouse embryo cDNA library in yeast. One of the strongest interactions identified the histone binding protein RbAp48. RbAp48 also interacted weakly with CBP alone but did not interact with phosphorylated or nonphosphorylated CREB. CBP (or its homologue p300) from HeLa cell nuclear extracts coimmunoprecipitated with RbAp48 and its homologue RbAp46 and bound to a glutathione S-transferase-RbAp48 fusion protein. This interaction was stimulated by the addition of phosphorylated CREB and allowed the association of core histones and mononucleosomes in an acetylation-dependent manner. RbAp48 lowered the K(m) of CBP histone acetylase activity and facilitated p300-mediated in vitro transcription of a chromatinized template in the presence of acetylcoenzyme A. These data indicate that the association of phosphorylated CREB with CBP promotes the binding of RbAp48 and its homologue RbAp46, allowing the formation of a complex that facilitates histone acetylation during transcriptional activation.
Zhang
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Vollum Institute, Oregon Health Sciences University, Portland, Oregon 97201, USA.
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Goodman
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D000105:Acetyl Coenzyme A / Q000378:metabolism; D000107:Acetylation; D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D050882:CREB-Binding Protein; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D002843:Chromatin / Q000235:genetics; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism*; D050881:E1A-Associated p300 Protein; D006367:HeLa Cells / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D006801:Humans; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D056505:Retinoblastoma-Binding Protein 4; D013698:Templates, Genetic; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques; D015003:Yeasts / Q000235:genetics
D002352:Carrier Proteins; D002843:Chromatin; D017362:Cyclic AMP Response Element-Binding Protein; D006657:Histones; D009687:Nuclear Proteins; C082637:RBBP4 protein, human; C489969:Rbbp4 protein, mouse; D011994:Recombinant Proteins; D056505:Retinoblastoma-Binding Protein 4; D015534:Trans-Activators; D000105:Acetyl Coenzyme A; D000123:Acetyltransferases; D050882:CREB-Binding Protein; C494363:CREBBP protein, human; C494364:Crebbp protein, mouse; D050881:E1A-Associated p300 Protein; C494361:Ep300 protein, mouse