Nucleolin Interacts with Several Ribosomal Proteins through Its RGG Domain*
- Philippe Bouvet‡§,
- Jean-Jacques Diaz¶,
- Karine Kindbeiter¶,
- Jean-Jacques Madjar¶ and
- François Amalric‡
- From the ‡Laboratoire de Biologie Moléculaire Eucaryote, Institut de Biologie Cellulaire et de Génétique du CNRS, UPR 9006, 118 route de Narbonne, 31062 Toulouse Cedex, France and ¶Immuno-Virologie Moléculaire et Cellulaire CNRS UMR5537, Faculté de Médecine Lyon-R.T.H. Laennec, Rue Guillaume Paradin, 69372 Lyon Cedex 08, France
Abstract
Nucleolin is one of the major nonribosomal proteins of the nucleolus. Through its four RNA-binding domains, nucleolin interacts specifically with pre-rRNA as soon as synthesis begins, but it is not found in mature cytoplasmic ribosomes. Nucleolin is able to shuttle between the cytoplasm and the nucleus. These data suggest that nucleolin might be involved in the nucleolar import of cytoplasmic components and in the assembly of pre-ribosomal particles. Here we show, using two-dimensional blots in a ligand blotting assay, that nucleolin interacts with 18 ribosomal proteins from rat (14 and 4 from the large and small subunit, respectively). The C-terminal domain of nucleolin (p50) interacts with 10 of these identified ribosomal proteins. In vitro binding assays show that the glycine-arginine rich domain of nucleolin (RGG domain) is sufficient for the interaction with one of these proteins. Interestingly, most of the proteins that interact with p50 belong to the core ribosomal proteins, which are resistant to extraction with high salt concentration. These findings suggest that nucleolin might be involved in the nucleolar targeting of some ribosomal proteins and in their assembly within pre-ribosomal particles.
Footnotes
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↵* This work was supported by the CNRS and UniversitéClaude Bernard Lyon 1 (to J.-J. M.) and by grants from the CNRS, University Paul Sabatier, and Association pour la Recherche contre le Cancer (ARC) (to P. B and F. A.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵§ To whom correspondence should be addressed. Tel.: 33-5-61-33-59-52; Fax: 33-5-61-33-58-86; E-mail: bouvet{at}ibcg.biotoul.fr.
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↵1 The abbreviations used are: RBD, RNA-binding domain(s); PAGE, polyacrylamide gel electrophoresis; NTA, nitrilotriacetic acid.
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- Received March 12, 1998.
- Revision received May 18, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
