Role of amino acid residue 187 of poliovirus polypeptide 2C in determining the guanidine trait.

Although mutations in codons 164 and 179 of poliovirus polypeptide 2C can establish guanidine resistance, the majority of guanidine-resistant and guanidine-dependent viruses contain an M----L change at amino residue 187 along with other critical mutations. The change at residue 187 probably contributes to the guanidine phenotype along with a variety of other modifications in polypeptide 2C, possibly altering conformation of the polypeptide during the initiation step of viral RNA synthesis.