May play a role in signal transduction pathways that involve calcium as a second messenger (By similarity). May be a signaling component in the response to gibberellin and cold stress (PubMed:15604699). 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. Expressed in roots (Ref.2). Expressed in leaf sheaths (Ref.2, PubMed:15604699). By gibberellin (Ref.2, PubMed:15604699). Induced by cold stress (Ref.2, PubMed:15604699, PubMed:26681628). Down-regulated by brassinosteroid, abscisic acid (ABA), and drought or cold stresses (PubMed:15604699). 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 (343-373) inactivates kinase activity under calcium-free conditions. Plants over-expressing CPK7 show increased recovery rates after cold stress. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. CDPK subfamily.