Differentiation between SV40 large-T and U antigenic sites

Radioimmune precipitation, SDS-polyacrylamide slab gel electrophoresis and fluorography were used to investigate the SV40 large-T and U antigenic sites on species of proteins synthesized during wild type and tsA58 mutant infections in TC7 monkey cells. Wild type infection at 33 and 41.5 degrees C and the A58 infection at 33 degrees C produced similar profiles of three species ranging in mol. wt. from 84000 to 94000, all of which had both the large-T and U antigenic sites. The A58 infection at 41.5 degrees C, however, produced an additional four discrete species ranging in mol. wt. from 60000 to 74000 that contained the large-T site(s), but not the U site(s). A subpopulation of the 74000 mol. wt. species contained both sites. Therefore, the region of the A58 mutant 94000 mol. wt. species containing the U antigenic site(s), the COOH-terminal region, appears to be more sensitive to processing, probably proteolytic cleavage, than does the region containing the large-T antigenic site(s).