5'-terminal structure of poliovirus polyribosomal RNA is pUp

Poliovirus RNA purified from virus-specific polyribosomes does not contain m7G in a 5'-5'-pyrophosphate linkage at its 5'-end. The only potential 5'-end found in ribonuclease digests of this RNA is pUp, which is present in a yield of 1 mole/mole of poliovirus RNA. We conclude that a 5'-terminal m7G is not required for translation of at least one RNA species in animal cells.