SHORTENING OF THE POLY(A) TAIL AT THE 3'-END OF MESSENGER-RNA REQUIRES ITS TRANSLATION

We report here that when alpha- or beta-globin mRNAs were hybridized w ith their alpha- or beta-complementary DNAs, respectively, and then tr anslated in rabbit reticulocyte lysates, globin synthesis as well as s hortening of the poly(A) tail were much less than that observed with n onhybridized mRNA. Furthermore, when the hybrid (alpha-globin mRNA/alp ha-cDNA) was translated in the presence of nonhybrid (alpha-globin mRN A), the estimated average shortening of the poly(A) tails of the hybri d and the nonhybrid were 8% and 40%, respectively. Similar results wer e obtained when a hybridized beta-globin mRNA with beta-cDNA was incub ated in the same translation mixture with beta-globin mRNA. No globin synthesis occurred in the mixtures containing the cDNA-mRNA hybrids on ly. In the mixtures containing both the hybrid and the nonhybridized m RNAs, globin was synthesized at a rate similar to that observed in a t ranslation reaction mixture alone, that is, in the absence of any hybr id.