title: Canonical eukaryotic initiation factors determine initiation of translation by internal ribosomal entry.
abstract: Translation of picornavirus RNA is initiated after ribosomal binding to an internal ribosomal entry site (IRES) within the 5' untranslated region. We have reconstituted IRES-mediated initiation on encephalomyocarditis virus RNA from purified components and used primer extension analysis to confirm the fidelity of 48S preinitiation complex formation. Eukaryotic initiation factor 2 (eIF2), eIF3, and eIF4F were required for initiation; eIF4B and to a lesser extent the pyrimidine tract-binding protein stimulated this process. We show that eIF4F binds to the IRES in a novel cap-independent manner and suggest that cap- and IRES-dependent initiation mechanisms utilize different modes of interaction with this factor to promote ribosomal attachment to mRNA.
authors.affiliation: Department of Microbiology and Immunology, Morse Institute for Molecular Genetics, State University of New York Health Science Center at Brooklyn, 11203-2098, USA.
authors.forename: T V
authors.initials: TV
authors.lastname: Pestova
authors.forename: C U
authors.initials: CU
authors.lastname: Hellen
authors.forename: I N
authors.initials: IN
authors.lastname: Shatsky
mesh_terms: D001483:Base Sequence; D015852:Eukaryotic Initiation Factor-2 / Q000235:genetics* / Q000378:metabolism; D039562:Eukaryotic Initiation Factor-4F; D008969:Molecular Sequence Data; D010448:Peptide Initiation Factors / Q000235:genetics* / Q000378:metabolism; D010849:Picornaviridae / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D012367:RNA, Viral / Q000235:genetics*; D012270:Ribosomes / Q000235:genetics*
chemical_list: D015852:Eukaryotic Initiation Factor-2; D039562:Eukaryotic Initiation Factor-4F; D010448:Peptide Initiation Factors; D012333:RNA, Messenger; D012367:RNA, Viral