Indispensable for virus replication. Indispensable for virus replication. Mediates the cap-independent, EIF4E-dependent translation of viral genomic RNAs (By similarity). Binds to the cap-binding site of host EIF4E and thus interferes with the host EIF4E-dependent mRNA export and translation (By similarity). VPg-RNA directly binds EIF4E and is a template for transcription (By similarity). Also forms trimeric complexes with EIF4E-EIF4G, which are templates for translation (By similarity). Has RNA-binding and proteolytic activities. An RNA-dependent RNA polymerase that plays an essential role in the virus replication. a ribonucleoside 5'-triphosphate + RNA(n) = diphosphate + RNA(n+1) Hydrolyzes glutaminyl bonds, and activity is further restricted by preferences for the amino acids in P6 - P1' that vary with the species of potyvirus, e.g. Glu-Xaa-Xaa-Tyr-Xaa-Gln-|-(Ser or Gly) for the enzyme from tobacco etch virus. The natural substrate is the viral polyprotein, but other proteins and oligopeptides containing the appropriate consensus sequence are also cleaved. Probably colocalizes with 6K2-induced vesicles associated with host chloroplasts. 6K-induced vesicles associate with host chloroplasts. VPg is uridylylated by the polymerase and is covalently attached to the 5'-end of the genomic RNA. This uridylylated form acts as a nucleotide-peptide primer for the polymerase (By similarity). The viral RNA1 of bymoviruses is expressed as a single polyprotein which undergoes post-translational proteolytic processing by the main proteinase NIa-pro resulting in the production of at least eight individual proteins. Belongs to the bymoviruses polyprotein 1 family.