The joining of ribosomal subunits in eukaryotes requires eIF5B (original) (raw)
- Letter
- Published: 20 January 2000
- Ivan B. Lomakin1,
- Joon H. Lee3,
- Sang Ki Choi3,
- Thomas E. Dever3 &
- …
- Christopher U. T. Hellen1
Nature volume 403, pages 332–335 (2000)Cite this article
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Abstract
Initiation of eukaryotic protein synthesis begins with the ribosome separated into its 40S and 60S subunits1. The 40S subunit first binds eukaryotic initiation factor (eIF) 3 and an eIF2–GTP–initiator transfer RNA ternary complex. The resulting complex requires eIF1, eIF1A, eIF4A, eIF4B and eIF4F to bind to a messenger RNA and to scan to the initiation codon2. eIF5 stimulates hydrolysis of eIF2-bound GTP and eIF2 is released from the 48S complex formed at the initiation codon before it is joined by a 60S subunit to form an active 80S ribosome3,4,5,6,7,8. Here we show that hydrolysis of eIF2-bound GTP induced by eIF5 in 48S complexes is necessary but not sufficient for the subunits to join. A second factor termed eIF5B (relative molecular mass 175,000) is essential for this process. It is a homologue of the prokaryotic initiation factor IF2 (refs 6, 7) and, like it8,9,10,11,12, mediates joining of subunits and has a ribosome-dependent GTPase activity that is essential for its function.
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Acknowledgements
We thank W. Merrick for discussions, D. Etchison and R. Schneider for antibodies, and L. Siconolfi-Baez for sequencing eIF5B. These studies were supported by grants from the NIH to C.U.T.H. and T.V.P.
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- Department of Microbiology and Immunology State University of New York Health Science Center at Brooklyn, 450 Clarkson Avenue, Brooklyn, 11203, New York, USA
Tatyana V. Pestova, Ivan B. Lomakin & Christopher U. T. Hellen - A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, 119899, Russia
Tatyana V. Pestova - Laboratory of Eukaryotic Gene Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, 20892-2716, Maryland, USA
Joon H. Lee, Sang Ki Choi & Thomas E. Dever
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Correspondence toTatyana V. Pestova.
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Pestova, T., Lomakin, I., Lee, J. et al. The joining of ribosomal subunits in eukaryotes requires eIF5B.Nature 403, 332–335 (2000). https://doi.org/10.1038/35002118
- Received: 13 September 1999
- Accepted: 16 November 1999
- Issue Date: 20 January 2000
- DOI: https://doi.org/10.1038/35002118