Interaction with the NMDA receptor locks CaMKII in an active conformation

Calcium- and calmodulin-dependent protein kinase II (CaMKII) and glutamate receptors are integrally involved in forms of synaptic plasticity that may underlie learning and memory. In the simplest model for long-term potentiation 1 , CaMKII is activated by Ca 2+ influx through NMDA ( N -methyl- d -aspartate) receptors and then potentiates synaptic efficacy by inducing synaptic insertion 2 , 3 and increased single-channel conductance 4 of AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) receptors. Here we show that regulated CaMKII interaction with two sites on the NMDA receptor subunit NR2B provides a mechanism for the glutamate-induced translocation of the kinase to the synapse in hippocampal neurons. This interaction can lead to additional forms of potentiation by: facilitated CaMKII response to synaptic Ca 2+ ; suppression of inhibitory autophosphorylation of CaMKII; and, most notably, direct generation of sustained Ca 2+ /calmodulin (CaM)-independent (autonomous) kinase activity by a mechanism that is independent of the phosphorylation state. Furthermore, the interaction leads to trapping of CaM that may reduce down-regulation of NMDA receptor activity 5 . CaMKII–NR2B interaction may be prototypical for direct activation of a kinase by its targeting protein.