Transcription activator that binds DNA cooperatively with DP proteins through the E2 recognition site, 5'-TTTC[CG]CGC-3' found in the promoter region of a number of genes whose products are involved in cell cycle regulation or in DNA replication. The DRTF1/E2F complex functions in the control of cell-cycle progression from G1 to S phase. E2F3 binds specifically to RB1 in a cell-cycle dependent manner. Inhibits adipogenesis, probably through the repression of CEBPA binding to its target gene promoters (PubMed:20176812). Component of the DRTF1/E2F transcription factor complex. Binds cooperatively with TFDP1/Dp-1 to E2F sites. Interacts with retinoblastoma protein RB1 and related proteins (such as RBL1) that inhibit the E2F transactivation domain. Binds EAPP. In the developing nervous system, high levels expressed in both ventral and dorsal regions of the spinal cord from 13.5 dpc. Also expressed in dorsal root and cranial ganglia in 11.5-18.5 dpc embryos. Only low levels of expression in developing brain. In the developing retina (15.5 dpc), expression of E2F3 is localized to the ganglion cell layer. In other developing tissues, expressed in liver, lung and heart. Weak expression in developing kidney and skeletal muscle. Absent from the developing choroid plexus, thymus and developing skin. Low levels of expression in the developing intestinal epithelium and mesenchyme in 12.5-18.5 dpc embryos. Belongs to the E2F/DP family.