No abstract

Extracts from poliovirus-infected HeLa cells were used to study ribosome binding of native and denatured reovirus mRNAs and translation of capped mRNAs with different degrees of secondary structure. Here, we demonstrate that ribosomes in extracts from poliovirus-infected cells could form initiation complexes with denatured reovirus mRNA, in contrast to their inability to bind native reovirus mRNA. Furthermore, the capped alfalfa mosaic virus 4 RNA, which is most probably devoid of stable secondary structure at its 5' end, could be translated at much higher efficiency than could other capped mRNAs in extracts from poliovirus-infected cells.The cap structure at the 5' terminus of almost all eucaryotic mRNAs, m7GpppN(m) (30), has been shown to facilitate translation initiation complex formation (for a recent review see reference 2). However, the degree of dependence on the cap structure for translation varies among different capped mRNAs, as indicated by variable extents of decrease in translation due to decapping (24,27) or addition of cap analogs (13,38). Moreover, the extent of dependence on the cap structure for translation has been shown to be a function of salt concentration (6, 39, 40), temperature (38), and the concentration of initiation factors (IF) (12). It was believed that the function of the cap structure is mediated by a cap-binding protein (CBP), and consequently, a 24-kilodalton (Kd) polypeptide was identified by specific cross-linking to the 5' oxidized cap structure of reovirus mRNA (33) and purified to apparent homogeneity by m7GDP-Sepharose 4B

No abstract

Extracts from poliovirus-infected HeLa cells were used to study ribosome binding of native and denatured reovirus mRNAs and translation of capped mRNAs with different degrees of secondary structure. Here, we demonstrate that ribosomes in extracts from poliovirus-infected cells could form initiation complexes with denatured reovirus mRNA, in contrast to their inability to bind native reovirus mRNA. Furthermore, the capped alfalfa mosaic virus 4 RNA, which is most probably devoid of stable secondary structure at its 5′ end, could be translated at much higher efficiency than could other capped mRNAs in extracts from poliovirus-infected cells.

No abstract