DcE2F, a functional plant E2F-like transcriptional activator from Daucus carota

in animal cells the progression of the cell cycle through G(1)/S transition and S phase is under the control of the pRB/E2F regulatory pathway. The E2 F transcription factors are key activators of genes coding for several regu latory proteins and for enzymes involved in nucleotide and DNA synthesis. I n this report we have detected the presence of E2F-like DNA binding activit ies in carrot nuclear extracts, and we have isolated a carrot cDNA (DcE2F) encoding a plant E2F homologue. The DcE2F gene is expressed in proliferatin g cells and is induced during the G(1)/S transition of the cell cycle, Supe rshift experiments using anti-DcE2F antiserum have confirmed that the DcE2F protein is a component of the carrot E2F-like nuclear activities. DNA bind ing assays have demonstrated that the DcE2F protein can recognize a canonic al E2F cis-element in association with a mammalian DP protein. Furthermore, transactivation assays have revealed that DcE2F is a functional transcript ion factor that can transactivate, together with a DP partner, an E2F-respo nsive reporter gene in both plant and mammalian cells.