CIPK serine-threonine protein kinases interact with CBL proteins. Binding of a CBL protein to the regulatory NAF domain of CIPK protein lead to the activation of the kinase in a calcium-dependent manner (By similarity). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with CBL2 (PubMed:11577192, PubMed:19832944, PubMed:18237745, PubMed:25058458). Interacts with CBL3 (PubMed:19832944, PubMed:25058458). Interacts with CBL8 (PubMed:19832944). Interacts with CBL9 (PubMed:25058458). Interacts with KIN10 and KIN11 (PubMed:25058458). Targeted to the tonoplast when interacting with CBL2 or CBL3 and to the cell membrane when interacting with CBL8. Predominant in roots, cauline leaves, and flowers (PubMed:11577192). Ubiquitous with highest expression in 7-day-old seedlings and flower buds, followed by that in cauline leaves and young siliques (PubMed:25058458). First observed in imbibed seeds. Mostly localized in hypocotyls during germination and in seedlings. In mature plants, confined to vascular tissues of leaves and roots. In flowers, expressed in the vascular bundle of the stamen filament and in the stigma, where the filament joins the pistil. By light in a cytokinin-dependent manner and N(6)-benzylaminopurine (BA). Also induced by sucrose, glucose and fructose. Induced by several abiotic stresses like salt, cold, heat, oxidative, drought, PEG8000, glucose treatments as well exogenous abscisic acid (ABA) application (PubMed:25058458). The activation loop within the kinase domain is the target of phosphorylation/activation by upstream protein kinases. The PPI motif mediates the interaction with the ABI (abscisic acid-insensitive) phosphatases (By similarity). Increased sensitivity to glucose. Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. SNF1 subfamily.