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Free Initiation Factors eIF4A and eIF4B Are Dispensable for Translation Initiation on Uncapped mRNAs

P. A. Sakharov and S. Ch. Agalarov*

Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; E-mail: sultan@vega.protres.ru

* To whom correspondence should be addressed.

Received July 14, 2016; Revision received August 26, 2016
The formation of ribosomal 48S initiation complexes at the start AUG codon of uncapped mRNA leader sequences was studied using the methodology of primer extension inhibition (toe-printing). The experiments were performed in the system composed of purified individual components required for translation initiation. The formation of ribosomal 48S initiation complexes at the initiation codon was tested depending on the presence of the initiation factors eIF4F, eIF4A, and eIF4B. Several mRNAs containing short leader sequences lacking the extended secondary structure were studied. It was found that 48S ribosomal complexes at mRNAs with such leaders were not formed in the absence of eIF4F. In contrast, the removal of either eIF4A or eIF4B from the experimental system was found to be dispensable for the formation of the 48S complex.
KEY WORDS: translation initiation, 48S ribosomal initiation complex, initiation factors, eIF4F, eIF4A, eIF4B, toe-printing

DOI: 10.1134/S0006297916100175