POLY(A) DEPENDENT TRANSLATION IN RABBIT RETICULOCYTE LYSATE

Poly(A) tail has been known to enhance mRNA translation in eukaryotic cells. However, the effect of poly(A) tail in in vitro is rather small . Rabbit reticulocyte lysate (RRL) is widely used for studying transla tion in vitro. Translation in RRL is typically performed in nuclease-t reated lysate in which most of the endogenous mRNA have been removed. In this condition, the difference in the translational efficiency betw een poly(A)(+) and poly(A)(-) mRNAs is about two-fold. We studied the effect of poly(A) tail on luciferase mRNA translation in nuclease untr eated rabbit reticulocyte lysate, in which endogenous globin mRNAs wer e actively translated. In the case of capped mRNAs, stimulation of tra nslation by poly(A) addition was about 1.5- to 1.6-fold and the effect of the poly(A) length was small. However, in the case of uncapped mRN As, the addition of poly(A) tail increased luciferase expression over 10-fold. The effect of the poly(A) tail was dependent on its length. T he difference in the translational efficiency was not due to the chang e of mRNA stability. These data indicate that RRL has the potential to translate mRNA in a poly(A) dependent manner.