title: Human ribosomal protein L5 contains defined nuclear localization and export signals.
abstract: Ribosomal protein L5 is part of the 60 S ribosomal subunit and localizes in both the cytoplasm and the nucleus of eukaryotic cells, accumulating particularly in the nucleoli. L5 is known to bind specifically to 5 S rRNA and is involved in nucleocytoplasmic transport of this rRNA. Here, we report a detailed analysis of the domain organization of the human ribosomal protein L5. We show that a signal that mediates nuclear import and nucleolar localization maps to amino acids 21-37 within the 297-amino acid L5 protein. Furthermore, carboxyl-terminal residues at positions 255-297 serve as an additional nuclear/nucleolar targeting signal. Domains involved in 5 S rRNA binding are located at both the amino terminus and the carboxyl terminus of L5. Microinjection studies in somatic cells demonstrate that a nuclear export signal (NES) that maps to amino acids 101-111 resides in the central region of L5. This NES is characterized by a pronounced clustering of critical leucine residues, which creates a peptide motif not previously observed in other leucine-rich NESs. Finally, we present a refined model of the multidomain structure of human ribosomal protein L5.
authors.affiliation: Institute for Clinical and Molecular Virology, University Erlangen-Nürnberg, Schlossgarten 4, D-91054 Erlangen, Germany.
authors.forename: O
authors.initials: O
authors.lastname: Rosorius
authors.forename: B
authors.initials: B
authors.lastname: Fries
authors.forename: R H
authors.initials: RH
authors.lastname: Stauber
authors.forename: N
authors.initials: N
authors.lastname: Hirschmann
authors.forename: D
authors.initials: D
authors.lastname: Bevec
authors.forename: J
authors.initials: J
authors.lastname: Hauber
mesh_terms: D000595:Amino Acid Sequence; D002466:Cell Nucleolus / Q000378:metabolism; D003001:Cloning, Molecular; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D007202:Indicators and Reagents; D008164:Luminescent Proteins; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals; D012341:RNA, Ribosomal, 5S / Q000378:metabolism; D012269:Ribosomal Proteins / Q000737:chemistry*
chemical_list: D007202:Indicators and Reagents; D008164:Luminescent Proteins; D019913:Nuclear Localization Signals; D012341:RNA, Ribosomal, 5S; D012269:Ribosomal Proteins; C029742:ribosomal protein L5; D049452:Green Fluorescent Proteins