Calcium/calmodulin-dependent protein kinase that operates in the calcium-triggered CaMKK-CaMK1 signaling cascade. Phosphorylates and activates cmkB in vitro. Required in G1-phase of the cell cycle for proper timing of the initial nuclear division after germination as well as for subsequent nuclear division cycles. 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 may relieve intrasteric autoinhibition. The autoinhibitory domain overlaps with the calmodulin binding region and may be involved in intrasteric autoinhibition. Not lethal, but spores germinate with delayed kinetics and this lag corresponds to a delay in the G1-phase activation of the cyclin-dependent kinase nimX. Does not activate cmkB. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.