The scanning mechanism of eukaryotic translation initiation.
Annu Rev Biochem
; 83: 779-812, 2014.
Article
em En
| MEDLINE
| ID: mdl-24499181
ABSTRACT
In eukaryotes, the translation initiation codon is generally identified by the scanning mechanism, wherein every triplet in the messenger RNA leader is inspected for complementarity to the anticodon of methionyl initiator transfer RNA (Met-tRNAi). Binding of Met-tRNAi to the small (40S) ribosomal subunit, in a ternary complex (TC) with eIF2-GTP, is stimulated by eukaryotic initiation factor 1 (eIF1), eIF1A, eIF3, and eIF5, and the resulting preinitiation complex (PIC) joins the 5' end of mRNA preactivated by eIF4F and poly(A)-binding protein. RNA helicases remove secondary structures that impede ribosome attachment and subsequent scanning. Hydrolysis of eIF2-bound GTP is stimulated by eIF5 in the scanning PIC, but completion of the reaction is impeded at non-AUG triplets. Although eIF1 and eIF1A promote scanning, eIF1 and possibly the C-terminal tail of eIF1A must be displaced from the P decoding site to permit base-pairing between Met-tRNAi and the AUG codon, as well as to allow subsequent phosphate release from eIF2-GDP. A second GTPase, eIF5B, catalyzes the joining of the 60S subunit to produce an 80S initiation complex that is competent for elongation.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
RNA de Transferência de Metionina
/
Fator de Iniciação 1 em Eucariotos
/
Fator de Iniciação 5 em Eucariotos
/
Fator de Iniciação 3 em Eucariotos
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Subunidades Ribossômicas Menores de Eucariotos
Tipo de estudo:
Prognostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Revista:
Annu Rev Biochem
Ano de publicação:
2014
Tipo de documento:
Article