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Identification and partial characterization of new antigens from simian virus 40-transformed mouse cells
Abstract:
Two new species of antigens were detected in simian virus 40-transformed mouse cells, in addition to the large (94,000 daltons) and small (20,000 daltons) tumor antigens. These antigens were immunoprecipitated from cell extracts by using anti-T serum and not normal, nonimmune serum. One of these was a protein with a molecular weight of approximately 130,000 and was present in some but not all SV40-transformed mouse cells. The other, which we have named Tau antigen, has a molecular weight of 56,000 as estimated by electrophoresis through acrylamide gels and was found in all virus-transformed cells examined. The 13,000-daltons antigen contained about 15 methionine-tryptic peptides which were also present in the large SV40 tumor antigen as determined by ion-exchange chromatography. This strongly suggested that the protein was virus coded. The 56,000-dalton Tau antigen appeared to share only two methionine-tryptic peptides with the large species of SV40 tumor antigen, as determined by ion-exchange and paper chromatographies. Our results are compatible with a cellular origin for Tau antigen. However, our data do not exclude the possibility that this protein contains sequences specified by the virus DNA.
Insights
Researchers identified two new antigens in simian virus 40-transformed mouse cells. One antigen appears virus-coded, while the Tau antigen (56,000 daltons) may originate from the cell.
Area of Science:
- Virology
- Molecular Biology
- Oncology
Background:
- Simian virus 40 (SV40) transformation of mouse cells leads to the expression of tumor antigens.
- Understanding these antigens is crucial for comprehending viral oncogenesis.
Purpose of the Study:
- To identify and characterize novel antigens expressed in SV40-transformed mouse cells.
- To investigate the potential viral or cellular origin of these newly discovered antigens.
Main Methods:
- Immunoprecipitation of cell extracts using anti-T serum.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for molecular weight estimation.
- Peptide mapping using ion-exchange and paper chromatography to compare tryptic peptides.
Main Results:
- Two new antigens, approximately 130,000 and 56,000 daltons (Tau antigen), were detected alongside known large (94,000 daltons) and small (20,000 daltons) tumor antigens.
- The 130,000-dalton antigen shared numerous methionine-tryptic peptides with the large SV40 tumor antigen, suggesting a viral origin.
- The 56,000-dalton Tau antigen shared minimal peptide homology with the large tumor antigen, indicating a potential cellular origin, though viral sequence contribution cannot be excluded.
Conclusions:
- SV40-transformed cells express at least two novel antigens beyond the canonical tumor antigens.
- The 130,000-dalton antigen is likely virus-encoded, while the Tau antigen (56,000 daltons) may be of cellular origin, potentially modulated by viral transformation.