Involvement of human release factors eRF3a and eRF3b in translation termination and regulation of the termination complex formation.
Mol Cell Biol
; 25(14): 5801-11, 2005 Jul.
Article
em En
| MEDLINE
| ID: mdl-15987998
ABSTRACT
eRF3 is a GTPase associated with eRF1 in a complex that mediates translation termination in eukaryotes. In mammals, two genes encode two distinct forms of eRF3, eRF3a and eRF3b, which differ in their N-terminal domains. Both bind eRF1 and stimulate its release activity in vitro. However, whether both proteins can function as termination factors in vivo has not been determined. In this study, we used short interfering RNAs to examine the effect of eRF3a and eRF3b depletion on translation termination efficiency in human cells. By measuring the readthrough at a premature nonsense codon in a reporter mRNA, we found that eRF3a silencing induced an important increase in readthrough whereas eRF3b silencing had no significant effect. We also found that eRF3a depletion reduced the intracellular level of eRF1 protein by affecting its stability. In addition, we showed that eRF3b overexpression alleviated the effect of eRF3a silencing on readthrough and on eRF1 cellular levels. These results suggest that eRF3a is the major factor acting in translation termination in mammals and clearly demonstrate that eRF3b can substitute for eRF3a in this function. Finally, our data indicate that the expression level of eRF3a controls the formation of the termination complex by modulating eRF1 protein stability.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Terminação Traducional da Cadeia Peptídica
/
Fatores de Terminação de Peptídeos
Limite:
Animals
/
Humans
Idioma:
En
Revista:
Mol Cell Biol
Ano de publicação:
2005
Tipo de documento:
Article
País de afiliação:
França