title: A nuclear localization signal of human aryl hydrocarbon receptor nuclear translocator/hypoxia-inducible factor 1beta is a novel bipartite type recognized by the two components of nuclear pore-targeting complex.
abstract: Aryl hydrocarbon receptor nuclear translocator (ARNT) is a component of the transcription factors, aryl hydrocarbon receptor (AhR) and hypoxia-inducible factor 1, which transactivate their target genes, such as CYP1A1 and erythropoietin, in response to xenobiotic aromatic hydrocarbons and to low O2 concentration, respectively. Since ARNT was isolated as a factor required for the nuclear translocation of AhR from the cytoplasm in response to xenobiotics, the subcellular localization of ARNT has been of great interest. In this investigation, we analyzed the subcellular distribution of ARNT using transient expression of a fusion gene with beta-galactosidase and microinjection of recombinant proteins containing various fragments of ARNT in the linker region of glutathione S-transferase/green fluorescent protein. We found a clear nuclear localization of ARNT in the absence of exogenous ligands to AhR, and identified the nuclear localization signal (NLS) of amino acid residues 39-61. The characterized NLS consists of 23 amino acids, and can be classified as a novel variant of the bipartite type on the basis of having two separate regions responsible for efficient nuclear translocation activity, but considerable deviation of the sequence from the consensus of the classical bipartite type NLSs. Like the well characterized NLS of the SV40 T-antigen, this variant bipartite type of ARNT NLS was also mediated by the two components of nuclear pore targeting complex, PTAC58 and PTAC97, to target to the nuclear rim in an in vitro nuclear transport assay.
authors.affiliation: Department of Biochemistry, Saitama Cancer Center Research Institute, 818 Komuro, Ina-machi, Kitaadachi-gun, Saitama 362, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Eguchi
authors.forename: T
authors.initials: T
authors.lastname: Ikuta
authors.forename: T
authors.initials: T
authors.lastname: Tachibana
authors.forename: Y
authors.initials: Y
authors.lastname: Yoneda
authors.forename: K
authors.initials: K
authors.lastname: Kawajiri
mesh_terms: D000595:Amino Acid Sequence; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004921:Erythropoietin / Q000378:metabolism; D006367:HeLa Cells; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009685:Nuclear Envelope / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism*; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: C497396:ARNT protein, human; D004268:DNA-Binding Proteins; C497442:HIF1A protein, human; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D010446:Peptide Fragments; D018336:Receptors, Aryl Hydrocarbon; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D004921:Erythropoietin; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D019363:Cytochrome P-450 CYP1A1; D001616:beta-Galactosidase