title: Biochemical and phosphoproteomic analysis of the helix-loop-helix protein E47.
abstract: Numerous in vitro as well as genetic studies have demonstrated that the activities of the E2A proteins are regulated at multiple levels, including modulation of DNA binding by the Id proteins, association with the transcriptional modulators p300 and ETO, and posttranslational modifications. Here, we use affinity purification of tagged E47 combined with mass spectrometry in order to show that E47 interacts with the entire ensemble of Id proteins, namely, Id1, Id2, Id3, and Id4. Furthermore, we find that the lysine-specific histone demethylase 1 (LSD1), the protein arginine N-methyltransferase 5 (PRMT5), the corepressor CoREST, and the chaperones of the 14-3-3 family associate with affinity-purified E47. We also identify a spectrum of amino acid residues in E47 that are phosphorylated, including an AKT substrate site. We did, however, find that mutation of the identified AKT substrate site by itself did not perturb B cell development. In sum, these studies show that the entire ensemble of Id proteins has the ability to interact with E47, identify factors that associate with E47, and reveal a spectrum of phosphorylated residues in E47, including an AKT substrate site.
authors.affiliation: Division of Biological Sciences, University of California, San Diego, La Jolla, California, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Teachenor
authors.forename: Kristina
authors.initials: K
authors.lastname: Beck
authors.forename: Lilyan Y T
authors.initials: LY
authors.lastname: Wright
authors.forename: Zhouxin
authors.initials: Z
authors.lastname: Shen
authors.forename: Steven P
authors.initials: SP
authors.lastname: Briggs
authors.forename: Cornelis
authors.initials: C
authors.lastname: Murre
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D001483:Base Sequence; D002454:Cell Differentiation; D002460:Cell Line; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D040901:Proteomics; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D058127:Transcription Factor 3 / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D048948:14-3-3 Proteins; D058127:Transcription Factor 3; D051057:Proto-Oncogene Proteins c-akt