Evidence for differences in size and composition of the poliovirus-specific polypeptides in infected HeLa cells

The poliovirus specific capsid and noncapsid proteins have been shown by use of a radioisotopic method to have differences in amino acid composition. Differences in size were demonstrated by sucrose gradient analysis, molecular sieve chromatography and acrylamide gel electrophoresis. Molecular weights of all the virus-specific polypeptides were also obtained by the latter method; the molecular weights ranged from 79,000 to 5000. The total combined molecular weights of the fourteen virus-specific proteins is approximately 500,000 daltons. This mass greatly exceeds the 200,000 daltons of total protein expected to be encoded in the poliovirus genome which supports our previous evidence for large precursor proteins.