Human Ribosomal Protein L5 Contains Defined Nuclear Localization and Export Signals

• Published in: The Journal of biological chemistry Vol. 275; no. 16; pp. 12061 - 12068
• Main Authors: Rosorius, Olaf, Fries, Barbara, Stauber, Roland H., Hirschmann, Nicole, Bevec, Dorian, Hauber, Joachim
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 21.04.2000; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Sequence; Cell Nucleolus - metabolism; Cloning, Molecular; Green Fluorescent Proteins; HeLa Cells; Humans; Indicators and Reagents; Luminescent Proteins; Molecular Sequence Data; Nuclear Localization Signals; ribosomal protein L5; Ribosomal Proteins - chemistry; ribosomal subunit 60S; RNA, Ribosomal, 5S - metabolism; rRNA 5S
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.275.16.12061

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.