Aims The transcription factors bZIP19 and bZIP23 function as central regulators of the Zn deficiency response, and also as sensors of intracellular Zn concentration through their protein Zn-Sensor Motif (ZSM). While under Zn deficiency the target genes of bZIP19/23 are transcriptionally activated, under Zn sufficiency the binding of Zn 2+ ions to the ZSM halts gene expression. Mutations, including deletions, in the ZSM affect...