DE2F2, A NOVEL E2F-FAMILY TRANSCRIPTION FACTOR IN DROSOPHILA-MELANOGASTER

Mammalian E2F transcription factors comprise a family of proteins enco ded by distinct genes which function in the form of heterodimers with DP proteins. In Drosophila melanogaster, only a single E2F-related tra nscription factor, dE2F, has been reported. We have now identified and characterized a cDNA encoding another E2F family member in Drosophila , termed dE2F2, The predicted amino acid sequence shares 38.8% identit y with dE2F, including the QKRRIYDITNVLEGI motif which is highly conse rved in mammalian E2F family members and dE2F, The 18 amino acids, loc ated in the carboxy-terminal region of the mammalian E2F family, suffi cient for binding to pRb are also conserved in dE2F2, Band mobility sh ift analyses with glutathione S-transferase fusion proteins revealed d E2F2 binding to E2F-recognition sites to be dependent on the presence of dDP protein, in apparent contrast to dE2F. Furthermore, cotransfect ion experiments in Kc cells demonstrated dE2F2 repression of the PCNA gene promoter activity, while dE2F caused activation, the target site for the repression being identical to the dE2F-recognition site. (C) 1 998 Academic Press.