For example, the Lmyc IRES requires the eIF4F complex and interaction of both poly(A) tail binding protein (PABP) and eIF3 with eIF4G for translation .
The phosphorylation levels of eIF4E and 4E-BP1 are influenced by SGP-2 which, in turn, affects the Bcl-xL IRES-dependent translation by regulating the stability of eIF4F complex .
However, it is also reported that mTOR inhibitors or PI3K/mTOR dual inhibitors led to resistance by MYC-driven elevation of eIF4F
complex (Ilic et al.
As the mRNA is exported into the cytoplasm, its cap structure interacts with the eIF4F complex, whose main function is to facilitate the recruitment of ribosome to the 5' end of mRNA and the consequent initiation of translation.
Thus 4E-BPs compete with eIF4G for binding to the same site on eIF4E, thereby preventing the assembly of eIF4F complex and inhibiting initiation of cap dependent translation .
Orally administered leucine stimulates protein synthesis in skeletal muscle of postabsorptive rats in association with increased eIF4F
Formation of the eIF4F complex is regulated by competition between eIF4E binding proteins (4EBPs) and eIF4G for binding to eIF4E.
Thus, it seems likely that stress conditions, such as amino acid deprivation, may affect translational control by increased 4EBP1 abundance, which could inhibit eIF4F assembly, as well as by the well-established mechanism that involves diminished formation of ternary complex, with both the decrease in ternary complex formation and the increase in 4EBP1 abundance dependent on the eIF2[alpha]/ATF4 signaling pathway.
The other event is the binding of eIF4F
onto the 5 [m.sup.7]GTP cap of mRNA (Figure 1(a)).
Quando a 4E-BP1 e fosforilada, o eIF4E e liberado e pode unir-se, ao eIF4G e o qual esta tambem sob o controle do MTOR e ao eIF4A, formando o complexo ribossomal eIF4F
. A montagem desse complexo e necessaria para a continuacao da etapa de iniciacao da traducao do RNA-mensageiro ao ribossomo para realizar a sintese proteica (Rogero e Tirapegui, 2008).
The hyperphosphorylation of 4E-BP1 prevents binding to eIF4E and the formation of 4E-BP1-eIF4E complex, resulting in the assembly of the eIF4F
complex and translation initiation.
Quando a 4E-BP1 e fosforilada, o eIF4E e liberado e pode unir-se ao eIF4G--o qual esta tambem sob o controle do mTOR--e ao eIF4A, o que forma o complexo eIF4F
. A montagem desse complexo e necessaria para a continuacao da etapa de iniciacao da traducao do RNA-mensageiro em proteina (Anthony e colaboradores, 1999).