CaM kinase II as frequency decoder of Ca2+ oscillations

In many cell types, Ca²⁺ signals are organized in the form of repetitive spikes. The frequency of these intracellular Ca²⁺ oscillations increases with the level of stimulation, suggesting the existence of a frequency encoding phenomenon. The question arises as to how the frequency of Ca²⁺ oscillations can be decoded inside the cell. Ca²⁺/calmodulin kinase II has long been proposed as an attractive candidate, as it is a key target of Ca²⁺ signals. By immobilizing the Ca²⁺/calmodulin kinase II and subjecting it to pulses of Ca²⁺ of variable amplitude, duration, and frequency, De Koninck and Schulman⁽¹⁾ have shown for the first time that the autonomous activity of Ca²⁺/calmodulin kinase II is highly sensitive to the temporal pattern of Ca²⁺ oscillations. BioEssays 20 :607–610, 1998.© 1998 John Wiley & Sons Inc.