E2F4E2F5

E2F4E2F5 refers to a specific family of transcription factors within the E2F family. E2F proteins are crucial regulators of cell cycle progression and are involved in controlling the expression of genes required for DNA replication and cell division. E2F4 and E2F5 are distinct members of this family, often functioning together or in conjunction with other E2F proteins and their binding partners.

These transcription factors typically bind to consensus DNA sequences known as E2F sites, which are found in the promoter regions of target genes. The activity of E2F proteins is tightly regulated by a complex interplay of post-translational modifications and interactions with other cellular proteins, most notably the retinoblastoma (Rb) protein and its related proteins (p107, p130).

While E2F1, E2F2, and E2F3 are generally considered to be "activator" E2Fs that promote cell cycle entry, E2F4 and E2F5, along with E2F6, are often categorized as "repressor" E2Fs. They are thought to play a role in silencing gene expression, particularly during the G0 phase of the cell cycle when cells are quiescent. E2F4, in particular, has been shown to form complexes with pocket proteins like p130 and p107, which then actively repress the transcription of genes involved in proliferation. E2F5 has similar repressive functions. The precise mechanisms and specific gene targets of E2F4 and E2F5 continue to be areas of active research, contributing to our understanding of cell cycle control and potential therapeutic strategies for diseases like cancer.