Graphical representation of NRT1.1-mediated bistable control of nitrate signaling: at low nitrate concentration, high-affinity monomer A is bound by nitrate, which induces asynchronous motions that initiate dimer decoupling and then eventually establishes a stable monomeric state through the interactions with CBL9-activated kinase CIPK23. At high nitrate concentrations, both the monomers are bound by nitrate, which maintains synchronous motions with stable dimer coupling by indirectly inhibiting the kinase CIPK23 activity. To see this figure in color, go online.