Mechanism and regulation of calcium/calmodulin-dependent protein kinase IItargeting to the NR2B subunit of the N-methyl-D-aspartate receptor

Calcium influx through the N-methyl-D-aspartate (NMDA)-type glutamate recep tor and activation of calcium/calmodulin-dependent kinase II (CaMKII) are c ritical events in certain forms of synaptic plasticity. We have previously shown that autophosphorylation of CaMKII induces high-affinity binding to t he NR2B subunit of the NMDA receptor (Strack, S,, and Colbran, R, J, (1998) J, Biol, Chem. 273, 20689-20692), Here, we show that residues 1290-1309 in the cytosolic tail of NR2B are critical for CaMKII binding and identify by site directed mutagenesis several key residues (Lys(1292), Leu(1298), Arg( 1299), Arg(1300), Gln(1301), and Ser(1303)). Phosphorylation of NR2B at Ser 1303 by CaMKII inhibits binding and promotes slow dissociation of preformed CaMKII NR2B complexes, Peptide competition studies imply a role for the Ca MKII catalytic domain, but not the substrate-binding pocket, in the associa tion with NR2B. However, analysis of monomeric CaMKII mutants indicates tha t the holoenzyme structure may also be important for stable association wit h NR2B, Residues 1260-1316 of NR2B are sufficient to direct the subcellular localization of CaMKII in intact cells and to confer dynamic regulation by calcium influx, Furthermore, mutation of residues in the CaMKII-binding do main in full-length NR2B bidirectionally modulates colocalization with CaMK II after NMDA receptor activation, suggesting a dynamic model for the trans location of CaMKII to postsynaptic targets.