Hes1 belongs to the basic helix-loop-helix (bHLH) family of transcription factors. It is a transcriptional repressor of genes that require a bHLH protein for their transcription. The protein has a particular type of basic domain that contains a helix interrupting protein that binds to the N-box promoter region rather than the canonical enhancer box (E-box). As a member of the bHLH family, it is a transcriptional repressor that influences cell proliferation and differentiation in embryogenesis. HES1 regulates its own expression via a negative feedback loop, and oscillates with approximately 2-hour periodicity. HES1 influences the maintenance of certain stem cells and progenitor cells. Specifically, HES1 influences the timing of differentiation by repressing bHLH activators, and determines binary cell fate. HES1 has been shown to play a large role in both the nervous, and digestive systems. HES1 has been shown to influence these two systems partially through the Notch signaling pathway.