Autophosphorylation
Autophosphorylation is the process in which a kinase attaches a phosphate group to itself. When CaMKII is autophosphorylated, it becomes persistently active. Phosphorylation of the Threonine 286 site allows for the activation of the catalytic domain. Autophosphorylation is enhanced by the structure of the holoenzyme because it is present in two stacked rings. The close proximity of these adjacent rings increases the probability of phosphorylation of neighboring CaMKII enzymes, furthering autophosphorylation. A mechanism that promotes autophosphorylation features inhibition of the PP1 phosphatase. This enables CaMKII to be constantly active by increasing the likelihood of autophosphorylation.
Read more about this topic: Ca2+/calmodulin-dependent Protein Kinase