UNUSUAL PROLIFERATION ARREST AND TRANSCRIPTIONAL CONTROL PROPERTIES OF A NEWLY DISCOVERED E2F FAMILY MEMBER, E2F-6

E2F transcription factors play an important role in the regulation of cell cycle progression. We report here the cloning and characterizatio n of an additional member of this family, E2F-6. E2F-6 lacks pocket pr otein binding and transactivation domains, and it is a potent transcri ptional repressor that contains a modular repression domain at its car boxyl terminus. Overproduction of E2F-6 had no specific effect on cell cycle progression in asynchronously growing Saos2 and NIH 3T3 cells, but it inhibited emery into S phase of NIH 3T3 cells stimulated to exi t G(0). Taken together, these data suggest that E2F-6 can regulate a s ubset of E2F-dependent genes whose products are required for entry int o the cell cycle but not for normal cell cycle progression.