Heterodimerization with LBP-1b is necessary for nuclear localization of LBP-1a and LBP-1c.
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.
Sato
Fuyuhiko
F
Department of Biomolecular Science, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan.
Yasumoto
Ken-ichi
K
Kimura
Kota
K
Numayama-Tsuruta
Keiko
K
Sogawa
Kazuhiro
K
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*
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