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. 1973 Jan;70(1):41–45. doi: 10.1073/pnas.70.1.41

Protein Initiation in Eukaryotes: Formation and Function of a Ternary Complex Composed of a Partially Purified Ribosomal Factor, Methionyl Transfer RNAf, and Guanosine Triphosphate

Daniel H Levin 1, David Kyner 1, George Acs 1
PMCID: PMC433179  PMID: 4509663

Abstract

A protein factor contained in a 1 M KCl extract of L-cell ribosomes and partially purified by chromatography on DEAE-cellulose forms a specific ternary complex with rat-liver Met-tRNAf and GTP. The complex is measured by its quantitative retention on nitrocellulose membranes. Complex assembly is optimal at 100 mM KCl and 0.2 mM MgCl2, and is independent of mRNA and of ribosomes. The GTP requirement can be replaced over 65% by its methylene analogue GDPCH2P, indicating that GTP hydrolysis is not involved. Complex formation is inhibited by 10 μM aurintricarboxylic acid, but is unaffected by 100 μM pactamycin, 100 μM fusidic acid, or by excess uncharged methionine tRNAf. The ternary complex is relatively stable and appears at the void volume during filtration on Sephadex G-100. At 1-3 mM MgCl2 and in the presence of other factors, the ternary complex is implicated in protein initiation by (i) its capacity to bind to the 40S ribosomal subunit to form a 48S complex; and (ii) the subsequent association of the 48S complex with a 60S subunit to form a functional “80S complex.”

Keywords: binding assay, L-cells, ribosome subunits, protein inhibitors

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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