Poliovirus protease 3C (P3-7c) does not cleave P220 of the eucaryotic mRNA cap-binding protein complex

Infection of HeLa cells by poliovirus results in proteolysis of the large subunit (P220) of the cap-binding protein complex. This is believed to cause the rapid shut-off of host protein synthesis during poliovirus infection. In this communication we examined the possible involvement of poliovirus proteins 3C (a proteinase) and 2C in cleavage of P220. Using antisera against these two viral polypeptides, we were unable to inhibit proteolysis of P220 in an in vitro assay. These results indicate that viral proteins 3C and 2C are not directly involved in cleaving P220 and hence do not cause shut-off of cellular protein synthesis.