Figure 1. The autoregulatory dimer model with positive feedback.

Promoter transitions are regulated by the dimerized transcription factor with rate and . is the transcription rate of active promotor, with a very small transcription rate of inactive promotor . is kinetic rate of translation, and are degradation rates of mRNA and protein, and are the rates of dimerization and de-dimerization. All the processes are modeled as elementary reactions and all reaction rates are rescaled by the protein decay rate (i.e. unless stated otherwise).