Identification of polypeptide components of adenovirus type 12 tumor antigen from productively and abortively infected cells and from tumor cells

Abstract

Adenovirus type 12 (Ad12) tumor antigen (T antigen) induced in productively infected KB cells, abortively infected rabbit RK13 cells, and hamster tumor cells (THA cells) was studied by immunoprecipitation and polyacrylamide gel electrophoresis. [ 35S]Methionine-labeled cell extracts were precipitated with anti-T serum, obtained from hamsters bearing tumors induced by Ad12, and with anti-P serum, obtained from rabbits immunized against Ad12 early proteins induced in RK13 cells. Two polypeptides with 31,000 (31K) and 19K molecular weights are precipitated from all cells. Polypeptides with 16K, 15K, 13K, and 10.5K molecular weights are observed in extracts from KB and THA cells only. T antigen from tumor cells also contains 57K, 50K, 45K, 41K, and 34K polypeptides. Polypeptides with 39K, 28K, and 25K molecular weights are synthesized in KB and RK13 cells, mainly when the cells are pretreated with cycloheximide, but are never seen in extracts from tumor cells. Anti-P serum precipitates the 39K, 31K, 28K, 25K, and 19K polypeptides and also a 60K polypeptide from KB and RK13 cells, which probably corresponds to the DNA-binding protein.