title: Heterodimerization with LBP-1b is necessary for nuclear localization of LBP-1a and LBP-1c.
abstract: The LBP-1 family consists of four proteins, which act as transcription factors in the formation of dimers with a member of this family. LBP-1a and LBP-1b are splicing variants from one gene, and LBP-1c and LBP-1d also arise from the alternative splicing of another gene. Investigation of subcellular localization of LBP-1 proteins fused to YFP revealed that the LBP-1b was localized in the nucleus, whereas LBP-1a and LBP-1c were exclusively localized in the cytosol. The peptide of 36 amino acids encoded by exon 6, a specific exon used only for LBP-1b, possessed the function of a nuclear localization signal (NLS). Nuclear localization of LBP-1a and LBP-1c occurred when LBP-1b was co-expressed, suggesting that heterodimerization of LBP-1a and LBP-1c with LBP-1b is important for their nuclear transport. Transiently expressed LBP-1 proteins in COS-7 cells formed speckles in the nucleus. Most speckles overlapped with the PML body. The activity of LBP-1a for accumulation in the PML body was mapped in the N-terminal region.
authors.affiliation: Department of Biomolecular Science, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Fuyuhiko
authors.initials: F
authors.lastname: Sato
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Yasumoto
authors.forename: Kota
authors.initials: K
authors.lastname: Kimura
authors.forename: Keiko
authors.initials: K
authors.lastname: Numayama-Tsuruta
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Sogawa
mesh_terms: D021581:Active Transport, Cell Nucleus; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins / Q000378:metabolism*; D019281:Dimerization; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D008164:Luminescent Proteins; D019913:Nuclear Localization Signals; D014157:Transcription Factors; C085968:UBP1 protein, human; C054562:yellow fluorescent protein, Bacteria