The translational capacity of deadenylated ovalbumin messenger RNA

Abstract

We present evidence that the poly(A) sequence at the 3' end of ovalbumin mRNA has an effect on its translational efficiency in a reticulocyte lysate cell-free system. Polynucleotide phosphorylase has been used to remove selectively the poly(A) while leaving the rest of the molecule intact. It is shown that the stability of the mRNA in a cell free system is not appreciably affected by this procedure. Measurements of the size of ovalbumin-synthesizing polysomes, rate of peptide elongation, and number of rounds of translation per messenger show a generally reduced efficiency for deadenylated mRNA compared to native mRNA. No comparable difference was observed in experiments with a wheat germ cell-free system, which gives few rounds of translation per mRNA. This indicates that the effect results from a lowering of the efficiency of reinitiation on deadenylated mRNA.