Forms of TF-RNAP interactions and their corresponding parameters for modeling the probability of RNAP binding. A1 and A2 are transcription factors acting as activators of genes. R1 and R2 are transcription factors acting as repressors of genes. A box without label represents RNAP. A curve with a bar at the end represents a repression effect; a curve with an arrow at the end indicates either cooperation between transcription factors or activation of a gene by a transcription factor.
Chen et al. BMC Genomics 2008 9(Suppl 1):S18 doi:10.1186/1471-2164-9-S1-S18