Poliovirus is an RNA virus of the picornavirus group, which uses its RNA as mRNA. At its 5' end, the RNA genome has a viral protein (VPg) instead of a 5' cap. This is followed by a nontranslated leader sequence, and then a single long protein-coding region (~7000 nucleotides), followed by a poly-A tail. Observations were made that used radioactive amino acid analogues. Short period use of the radioactive amino acids results in labeling of only very long proteins, while longer periods of labeling result in several different short polypeptides. What conclusion is most consistent with the results of the radioactive labeling experiment?

Question

Quizplus · Accepted Answer

The observation that short period labeling results in only very long proteins suggests that the poliovirus RNA is translated into a single long protein. The observation that longer periods of labeling result in several different short polypeptides suggests that this long protein is then cleaved into shorter ones. This is consistent with the known processing of the poliovirus polyprotein during viral replication, where the polyprotein is cleaved into individual functional proteins by viral proteases.

Poliovirus Is an RNA Virus of the Picornavirus Group, Which