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Proc Natl Acad Sci U S A. 2007 Apr 3;104(14):5788-93. Epub 2007 Mar 26.

Reconfiguration of yeast 40S ribosomal subunit domains by the translation initiation multifactor complex.

Author information

  • 1Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, United Kingdom.

Abstract

In the process of protein synthesis, the small (40S) subunit of the eukaryotic ribosome is recruited to the capped 5' end of the mRNA, from which point it scans along the 5' untranslated region in search of a start codon. However, the 40S subunit alone is not capable of functional association with cellular mRNA species; it has to be prepared for the recruitment and scanning steps by interactions with a group of eukaryotic initiation factors (eIFs). In budding yeast, an important subset of these factors (1, 2, 3, and 5) can form a multifactor complex (MFC). Here, we describe cryo-EM reconstructions of the 40S subunit, of the MFC, and of 40S complexes with MFC factors plus eIF1A. These studies reveal the positioning of the core MFC on the 40S subunit, and show how eIF-binding induces mobility in the head and platform and reconfigures the head-platform-body relationship. This is expected to increase the accessibility of the mRNA channel, thus enabling the 40S subunit to convert to a recruitment-competent state.

PMID:
17389391
PMCID:
PMC1832216
DOI:
10.1073/pnas.0606880104
[PubMed - indexed for MEDLINE]
Free PMC Article
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