Has RNA-binding and proteolytic activities. An RNA-dependent RNA polymerase that plays an essential role in the virus replication. Involved in aphid transmission, cell-to-cell and systemis movement, encapsidation of the viral RNA and in the regulation of viral RNA amplification. 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. Genome polyprotein of potyviruses undergoes post-translational proteolytic processing by the main proteinase NIa-pro resulting in the production of at least ten individual proteins. The P1 proteinase and the HC-pro cleave only their respective C-termini autocatalytically. 6K1 is essential for proper proteolytic separation of P3 from CI (By similarity). Belongs to the potyviridae genome polyprotein family.