Ca(2+)-dependent protein kinase (PubMed:26662273). Negative regulator of stomatal closure and slow anion currents (PubMed:26662273). Unable to phosphorylate THI1 in vitro, but the kinase activity is essential for the stomatal closure regulation (PubMed:26662273). Phosphorylates FD (PubMed:25661797). May play a role in signal transduction pathways that involve calcium as a second messenger (Probable). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Activated by calcium. Autophosphorylation may play an important role in the regulation of the kinase activity (By similarity). Repressed by THI1 through a negative regulation of the autophosphorylation activity in the presence of Ca(2+) (PubMed:26662273). Interacts with THI1 (PubMed:26662273). Interacts with FD and FDP (PubMed:25661797). Expressed in primary roots, leaves, inflorescences, siliques and guard cells (PubMed:26662273). Expressed in the shoot apical meristem (PubMed:25661797). Up-regulated by abscisic acid treatment and drought stress, but not by thiamine. There are 3 contiguous domains conserved in the CDPK subfamily: a kinase domain, an autoinhibitory (junction) domain and a calmodulin-like domain. The autoinhibitory domain (337-367) inactivates kinase activity under calcium-free conditions (By similarity). Autophosphorylated. Increased sensitivity to abscisic acid stomatal closure (PubMed:26662273). Delayed floral transition (PubMed:25661797). Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. CDPK subfamily.