Fig. 4.

Overview of the effect of different ligand families on the expression of solute binding proteins. Activation and repression are represented by triangular and flat arrowheads, respectively. The thickness of the lines represents a stronger upregulation or downregulation of the expression of target SBPs. SBP, solute-binding protein; RP, regulatory protein; CCR, carbon catabolite repression; OA, organic acids; INM, inorganic nutrients and metal ions; AAP, amino acids and peptides; PQAC, polyamines and quaternary ammonium compounds.