Structural homology of DNA polymerase beta from various mammalian cells

DNA polymerase beta was purified from various mammalian cells, i.e. mouse myeloma, rat liver, rat ascites hepatoma cells, rabbit liver, pig liver, and calf thymus cells. The apparent molecular weights of the polypeptides composing these enzymes were all about 40,000, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Moreover, tryptic peptide maps of these enzymes after radioiodination with 125I indicated that the molecular structures of the enzymes were basically identical. No difference was detected in the peptide maps of the mouse and rabbit enzymes, and only a few of the 22 spots in the fingerprint of the mouse enzyme were not detected in that of the rat enzyme. Furthermore, the peptide maps of DNA polymerase beta's from normal and malignant rat cells differed in only one spot.