Distinct domains in ribosomal protein L5 mediate 5 S rRNA binding and nucleolar localization.
Ribosomal protein L5, a 34-kDa large ribosomal subunit protein, binds to 5 S rRNA and has been implicated in the intracellular transport of 5 S rRNA.  By immunofluorescence microscopy, L5 is detected mostly in the nucleolus with a fainter signal in the nucleoplasm, and it is known to also be a component of large ribosomal subunits in the cytoplasm.  5 S rRNA is transcribed in the nucleoplasm, and L5 is thought to play an important role in delivering 5 S rRNA to the nucleolus.  Using RNA-binding assays and transfection experiments, we have delineated the domains within L5 that confer its 5 S rRNA binding activity and that localize it to the nucleolus. We found that the amino-terminal 93 amino acids are necessary and sufficient to bind 5 S rRNA in vitro, while the carboxyl-terminal half of the protein, comprising amino acids 151-296, serves to localize the protein to the nucleolus. L5, therefore, has a modular domain structure reminiscent of other RNA transport proteins where one region of the molecule serves to bind RNA while another determines subcellular localization.
Michael
W M
WM
Howard Hughes Medical Institute, Philadelphia, Pennsylvania, USA.
Dreyfuss
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D000595:Amino Acid Sequence; D000818:Animals; D001105:Archaea / Q000378:metabolism; D002466:Cell Nucleolus / Q000378:metabolism*; D017124:Conserved Sequence; D018076:DNA, Complementary; D015723:Gene Library; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D012275:Oryza / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012341:RNA, Ribosomal, 5S / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012269:Ribosomal Proteins / Q000737:chemistry / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000378:metabolism; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D016324:Sequence Tagged Sites; D014162:Transfection
D018076:DNA, Complementary; D012341:RNA, Ribosomal, 5S; D011994:Recombinant Proteins; D012269:Ribosomal Proteins; C029742:ribosomal protein L5