Transcriptional genetic circuits from the literature. Figure illustrating the circuit architectures associated to Table 1. In the graphical representation, we have made the distinction between non-competition and competition models by solid and dashed arrowed lines, respectively. In the notation n1, n2, ... characterizing the interactions in the schematic figures, the comma separates various binding sites and the degree of the multimer binding to that site. The notation n1 + n2 is employed only for subfigure (c) - see discussion in the Table 1.