Precursor from which the RNA-dependent RNA polymerase (RdRp) is probably released. RNA-dependent RNA polymerase plays an essential role in virus replication (Potential). a ribonucleoside 5'-triphosphate + RNA(n) = diphosphate + RNA(n+1) Specific enzymatic cleavages in vivo yield mature proteins. The protease probably cleaves itself and releases the RdRp (Potential). Cleavages have been shown in the P1 protein, but since the N-terminus containing the serine protease is shared between P1 and P1-P2, cleavages should also occur within the P1-P2 protein. Produced by -1 ribosomal frameshifting between codons 461 and 462.