[i] This table describes the rules determining gene expression when a single protein regulates genes. The rules show the regulatory protein complexes (protein and effector-metabolite), when present. We distinguish two types of conformation of regulators notated as P when they bind to their DNA-binding site with no effector, and as P-i regulators when they bind to DNA with the effector present. In the case of an absent protein, we assume that the expression state depends on the promoter strength.