Calcium/calmodulin-dependent protein kinase that operates in the calcium-triggered CaMKK-CaMK1 signaling cascade. Required in G1-phase of the cell cycle for proper timing of the initial nuclear division after germination, but not for subsequent mitoses. Required for the normal temporal regulation of nimX activity. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Activated by Ca(2+)/calmodulin. Binding of calmodulin results in conformational change that relieves intrasteric autoinhibition and allows phosphorylation of Thr-179 within the activation loop by cmkC. The autoinhibitory domain overlaps with the calmodulin binding region and interacts in the inactive folded state with the catalytic domain as a pseudosubstrate. Phosphorylated by cmkC on Thr-179. Lethal. Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. CaMK subfamily.