Involved in the modulation of stomatal movement. Promotes stomatal opening. May play a role in the regulation of chitin signaling. May be involved in biotic and abiotic stress responses. Interacts (via IQ domain) with CAM5. Highly expressed in leaf mesophyll cells (PubMed:17032064). Expressed in roots, rosette and cauline leaves, stems, flowers and siliques (Ref.6). By light, cadmium and lead. Down-regulated by salt stress and treatment with mannitol. Reduced primary root length. Reduced stomatal aperture.