Fig. 5.

Transitions between promoter states for multiple DNA binding sites (n = 3). G_i denotes the set of promoter states with i out of total n binding sites occupied by activator (X = A) or repressor (X = R) dimers. Our model conservatively assumes that the binding of X₂ does not affect the binding or unbinding of the next transcription factor to an adjacent site (no cooperativity). We also assume that the transcription rate is equal to ρ_b for G₁,G₂, … G_n promoter states.