E2F1E2F3

E2F1E2F3 refers to a specific heterodimeric complex formed by two members of the E2F family of transcription factors, E2F1 and E2F3. E2F proteins are a family of transcription factors that play a crucial role in the regulation of cell cycle progression and are involved in processes such as DNA replication, cell division, and apoptosis. E2F transcription factors function by binding to specific DNA sequences known as E2 sites, which are typically found in the promoter regions of genes involved in cell proliferation.

The formation of the E2F1E2F3 complex is a significant event in cellular control. E2F1 and E2F3 are themselves considered "activator" E2Fs, meaning they can promote the transcription of target genes. When E2F1 and E2F3 dimerize, they form a functional unit that can effectively bind to DNA and recruit transcriptional machinery to activate the expression of genes critical for cell cycle entry and progression. This complex is particularly important during the G1 to S phase transition of the cell cycle. The activity of the E2F1E2F3 complex is tightly regulated by retinoblastoma protein (Rb) and its related proteins (p107 and p130), which normally bind to E2Fs and inhibit their transcriptional activity. Upon activation of cyclin-dependent kinases (CDKs), Rb is phosphorylated, leading to the release of E2F1E2F3, allowing it to activate target gene expression and drive the cell into S phase. Dysregulation of E2F1E2F3 activity has been implicated in various cancers.