Description
Ca2+/CaM-dependent protein kinase II (CaM kinase II) is a ubiquitously expressed protein kinase that transduces elevated Ca2+ signals in cells to a number of target proteins ranging from ion channels to transcriptional activators. CaM kinase II has a unique holoenzyme structure and autoregulatory properties that allow it to give a prolonged response to transient Ca2+ signals and to sense cellular Ca2+ oscillations. In neurons CaM kinase II is highly expressed and localized with certain subcellular structures. Upon activation it can translocate to excitatory synapses where it regulates a number of proteins involved in synaptic transmission and its downstream signaling pathways. Changes in intracellular calcium can display variable responses ranging from highly localized, transient elevations within subcellular structures (e.g. a dendritic spine of a neuron) to Ca2+ waves that spread throughout the cell including the nucleus. The most ubiquitous calcium-sensing protein is Calmodulin (CaM), which contains four "EF" hand motifs with high specificity for binding Ca2+. The Ca2+/CaM complex interacts with and modulates the functionality of a large number of proteins including several Ser/Thr protein kinases