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Species-specific cellular DNA-binding proteins expressed in mouse cells transformed by chemical carcinogens
Abstract:
Mouse cells transformed by DNA and RNA tumor viruses and by chemical carcinogens have been examined for the presence of specific DNA-binding proteins by DNA-cellulose chromatography. Using mouse DNA-cellulose we have obtained single-stranded DNA-binding proteins from two clones transformed by chemical carcinogens. Simian virus 40 transformants also have a DNA-binding protein [the tumor (T) antigen] that binds to mouse and human DNA with comparable affinity. Mouse sarcoma virus-transformed cells and two other chemically transformed clones showed no difference in DNA-binding protein pattern compared to the untransformed parental cell. The DNA-binding proteins isolated from the chemically transformed cell clones are between 25,000 and 30,000 daltons by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. These cellular "T proteins" bind to the homologous mouse cellular DNA with a higher affinity than to heterologous human cellular DNA.
Insights
Researchers identified specific DNA-binding proteins in mouse cells transformed by chemical carcinogens. These cellular "T proteins" exhibit higher affinity for homologous mouse DNA than heterologous human DNA.
Area of Science:
- Molecular Biology
- Cancer Research
- Virology
Background:
- Tumorigenesis involves alterations in cellular DNA-binding proteins.
- Understanding these proteins is crucial for cancer research.
Purpose of the Study:
- To identify and characterize specific DNA-binding proteins in chemically and virally transformed mouse cells.
- To compare DNA-binding protein profiles between transformed and untransformed cells.
Main Methods:
- DNA-cellulose chromatography was used to isolate DNA-binding proteins.
- Sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) determined protein molecular weights.
- Binding affinity to homologous and heterologous DNA was assessed.
Main Results:
- Single-stranded DNA-binding proteins were isolated from two chemically transformed mouse cell clones.
- Simian virus 40 transformants possessed a tumor (T) antigen with broad DNA-binding affinity.
- Chemically transformed cells yielded specific cellular "T proteins" (25-30 kDa) with preferential binding to mouse DNA.
Conclusions:
- Specific cellular DNA-binding proteins are associated with chemical carcinogen-induced transformation in mouse cells.
- These proteins demonstrate a preference for homologous DNA, suggesting a role in cellular transformation.