title: Cytoplasmic tethering of a RING protein RBCK1 by its splice variant lacking the RING domain.
abstract: RBCC protein interacting with PKC 1 (RBCK1) is a transcription factor belonging to the RING-IBR protein family and has been shown to shuttle between the nucleus and cytoplasm, possessing both the nuclear export and localization signals within its amino acid sequence. RBCK2, lacking the C-terminal half of RBCK1 including the RING-IBR domain, has also been identified as an alternative splice variant of RBCK1. RBCK2 shows no transcriptional activity and instead it represses the transcriptional activity of RBCK1. Here, we show that RBCK2 is present usually in the cytoplasm containing two Leu-rich regions that presumably serve as a nuclear export signal (NES). Moreover, an NES-disrupted RBCK1 that is mostly localized within the nucleus is translocated to the cytoplasm when coexpressed with RBCK2, suggesting that RBCK2 serves as a cytoplasmic tethering protein for RBCK1. We propose a novel and general function of RING-lacking splice variants of RING proteins to control the intracellular localization and functions of the parental RING proteins by forming a hetero-oligomeric complex.
authors.affiliation: Department of Structural Molecular Biology, Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Yoshimoto
authors.forename: Kenji
authors.initials: K
authors.lastname: Tatematsu
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Koyanagi
authors.forename: Toshihide
authors.initials: T
authors.lastname: Okajima
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Tanizawa
authors.forename: Shun'ichi
authors.initials: S
authors.lastname: Kuroda
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D008156:Luciferases / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism; D017434:Protein Structure, Tertiary; D013997:Time Factors; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism; D014158:Transcription, Genetic; D044767:Ubiquitin-Protein Ligases
chemical_list: D014157:Transcription Factors; D008156:Luciferases; C504507:RBCK1 protein, human; D044767:Ubiquitin-Protein Ligases; D011493:Protein Kinase C