Mammalian translation initiation factor eIF1 functions with eIF1A and eIF3 in the formation of a stable 40 S preinitiation complex

Romit Majumdar, Amitabha Bandyopadhyay, Umadas Maitra

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Abstract

We have examined the role of the mammalian initiation factor eIF1 in the formation of the 40 S preinitiation complex using in vitro binding of initiator Met-tRNA (as Met-tRNAi·eIF2·GTP ternary complex) to 40 S ribosomal subunits in the absence of mRNA. We observed that, although both eIF1A and eIF3 are essential to generate a stable 40 S preinitiation complex, quantitative binding of the ternary complex to 40 S subunits also required eIF1. The 40 S preinitiation complex contained, in addition to eIF3, both eIF1 and eIF1A in a 1:1 stoichiometry with respect to the bound Met-tRNAi. These three initiation factors also bind to free 40 S subunits, and the resulting complex can act as an acceptor of the ternary complex to form the 40 S preinitiation complex (40 S·eIF3·eIF1·eIF1A·Met-tRNAi ·eIF2·GTP). The stable association of eIF1 with 40 S subunits required the presence of eIF3. In contrast, the binding of eIF1A to free 40 S ribosomes as well as to the 40 S preinitiation complex was stabilized by the presence of both eIF1 and eIF3. These studies suggest that it is possible for eIF1 and eIF1A to bind the 40 S preinitiation complex prior to mRNA binding.

Original languageEnglish (US)
Pages (from-to)6580-6587
Number of pages8
JournalJournal of Biological Chemistry
Volume278
Issue number8
DOIs
StatePublished - Feb 21 2003
Externally publishedYes

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RNA, Transfer, Met
Peptide Initiation Factors
Ribosome Subunits
Messenger RNA
Ribosomes
Stoichiometry
Association reactions
In Vitro Techniques

ASJC Scopus subject areas

  • Biochemistry

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Mammalian translation initiation factor eIF1 functions with eIF1A and eIF3 in the formation of a stable 40 S preinitiation complex. / Majumdar, Romit; Bandyopadhyay, Amitabha; Maitra, Umadas.

In: Journal of Biological Chemistry, Vol. 278, No. 8, 21.02.2003, p. 6580-6587.

Research output: Contribution to journalArticle

Majumdar, Romit ; Bandyopadhyay, Amitabha ; Maitra, Umadas. / Mammalian translation initiation factor eIF1 functions with eIF1A and eIF3 in the formation of a stable 40 S preinitiation complex. In: Journal of Biological Chemistry. 2003 ; Vol. 278, No. 8. pp. 6580-6587.
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