Synthesis of a class of DNA-binding proteins in synchronized untransformed and virus-transformed cells.

The synthesis of a classs of proteins with affinity for denatured DNA has been studied in synchronized cultures of the established hamster fibroblast line HIL-1 and its virus-transformed derivative NIL-1-hamster sarcoma virus. It has been found that the synthesis of a DNA-binding protein (P6, molecular weight 50 000) in synchronized untransformed NIL-1 cells follows a pattern different from that observed in the transformed cells. The protein is low in stationary cultures of NIL-1 and NIL-1-hamster sarcoma virus but increases after the cells are stimulated to grow, although the time of maximal P6 synthesis relative to cellular DNA synthesis is different in NIL-1 and NIL-1-hamster sarcoma virus. In contrast, the pattern of synthesis of two other DNA-proteins (P7 and P8') in essentially identical in synchronized untransformed and transformed cells. P7 is very low in resting cultures of both types of cells, but greatly increases early after the cells are stimulated to divide, while P8'is hish in stationary cultures and decreases slightly after the initiation of cellular DNA synthesis has occurred.