Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a Ser/Thr protein kinase whose activity is regulated by Ca2+/calmodulin (CaM) complex1. It is predominant in the heart and plays an important role during excitation contraction coupling2.

CaMKII was first purified from rat brain by gel filtration techniques while monitoring the activation of tryptophan hydrolase and phosphorylation of endogenous proteins3.

CaMK proteins belong to the kinase family4. CaMKII belongs to the CaMK subfamily of proteins which include the following members: CaMKI, CaMKII-alpha subunit, CaMKII-beta subunit, CaMKII-gamma subunit, CaMKII-delta subunit, CaMKIII and CaMKIV4.