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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1974 Aug;71(8):2946–2950. doi: 10.1073/pnas.71.8.2946

Met-tRNAfMet Binding to 40S Ribosomal Subunits: A Site for the Regulation of Initiation of Protein Synthesis by Hemin

Michael J Clemens *,†, Edgar C Henshaw ‡, Hannah Rahamimoff *,§, Irving M London *
PMCID: PMC388595  PMID: 4528641

Abstract

On incubation of reticulocyte lysates at 30° in the absence of added hemin, protein synthesis declines sharply within 4-6 min, due to the action of a translational inhibitor. Partially purified preparations of this inhibitor, in concentrations that inhibit protein synthesis in the lysate, cause reduced binding of Met-tRNAfMet to derived 40S ribosomal subunits in a ribosomal-salt-wash-dependent assay system. Neither the association of salt wash proteins with the subunits nor the level of Met-tRNAfMet bound in preformed 40S complexes is reduced by the inhibitor. No Met-tRNAfMet deacylase activity could be detected in the inhibitor preparation. Protein synthesis in reticulocyte lysates lacking added hemin or containing exogenous inhibitor is maintained by addition of small amounts of an initiation preparation factor, “F-MP,” which may be involved in the binding of Met-tRNAfMet to 40S subunits. This binding constitutes a site for control of protein synthesis by hemin in reticulocytes.

Keywords: translation control, initiation factors, buoyant density gradients

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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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