title: Characterization of a basic helix-loop-helix protein, ABF-1: nuclear localization, transcriptional properties, and interaction with Id-2.
abstract: The activated B-cell factor (ABF)-1 cDNA was initially isolated from Epstein-Barr virus (EBV)-infected B cells and codes for a DNA-binding protein belonging to the basic helix-loop-helix (bHLH) family of transcription factors. In this study, we characterized the nuclear localization signal of ABF-1, mapped two distinct transcriptional repression domains, and identified one ABF-1-interacting protein, Id-2. By examining the subcellular location of deletion mutants of ABF-1 fused to green fluorescent protein (GFP), critical regions involved in nuclear localization were determined. Analysis of GFP-tagged ABF-1 deletion mutants revealed two separate regions capable of directing nuclear localization. One region mapped to the N-terminal amino acids 71 to 103, whereas the second region localized to the C-terminal bHLH domain. Transient transfection of ABF-1 deletion mutants demonstrated that the N-terminal amino acids 1 to 40 and the bHLH domain function together to achieve maximum repression of E2A activity. Taken together, these results indicate that ABF-1 is a nuclear transcriptional repressor with two distinct regions that function in a synergistic fashion to attenuate E2A-mediated gene activation.
authors.affiliation: Department of Biology, University of the Pacific, Stockton, California 95211, USA.
authors.forename: J
authors.initials: J
authors.lastname: Wong
authors.forename: M
authors.initials: M
authors.lastname: Funes-Duran
authors.forename: J
authors.initials: J
authors.lastname: Ahlberg
authors.forename: J
authors.initials: J
authors.lastname: Round
authors.forename: R
authors.initials: R
authors.lastname: O'Connell
authors.forename: R
authors.initials: R
authors.lastname: Miller
authors.forename: E
authors.initials: E
authors.lastname: Chen
authors.forename: P A
authors.initials: PA
authors.lastname: Richmond
authors.forename: C A
authors.initials: CA
authors.lastname: Vierra
mesh_terms: D051792:Basic Helix-Loop-Helix Proteins; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D051797:Inhibitor of Differentiation Protein 2; D019913:Nuclear Localization Signals / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D051820:TCF Transcription Factors; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D051797:Inhibitor of Differentiation Protein 2; D019913:Nuclear Localization Signals; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D051820:TCF Transcription Factors; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors; C497450:ID2 protein, human; C112467:MSC protein, human; C544912:TCF7L1 protein, human