THE TRANSLATION EFFICIENCY OF OVALBUMIN MESSENGER-RNA IS DETERMINED IN PART BY A 5'-END HAIRPIN STRUCTURE

We have investigated the role in translation of the secondary structur e in the noncoding leader (NCL) sequence of ovalbumin mRNA. Deletion o f a stem-loop structure from the mRNA 5'-end (hairpin-1) produced a 2. 5-fold decrease in mRNA translation rate in both rabbit reticulocyte a nd wheat germ cell-free systems. A corresponding 2-fold reduction in m RNA binding affinity for reticulocyte eucaryotic initiation factor 2 ( eIF-2) was also observed. These effects were independent of mRNA cappi ng. Both translation rate and eIF-2 binding affinity were restored by addition to the mRNA of a sequence containing a hairpin-1-like structu re. The positive correlation between cell free translation rate and mR NA binding to eIF-2 suggests that hairpin-1 is both an initiation sign al and part of a specific eIF-2 recognition site. Methylation interfer ence indicated a direct interaction between eIF-2 and hairpin-1 of ova lbumin mRNA. (C) 1994 Academic Press, Inc.