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.