Involved in the resistance to some abiotic stresses (e.g. high salt, hyperosmotic stress) in young seedlings, by regulating the expression of several stress-inducible genes (cold- and salt-induced genes but not drought-responsive genes). Required for the ABA response during germination. 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. The CBL9/CIPK3 complex acts in the regulation of abscisic acid response in seed germination. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with CBL3 and CBL9. Mostly expressed in germinating seeds and young seedlings. Detected at low levels in roots, stems, leaves and flowers. By stresses such as cold, drought, high salt, wounding, and abscisic acid (ABA). 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). May be due to an intron retention. May be due to an intron retention. May be due to a competing acceptor splice site. Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. SNF1 subfamily.