NMDA receptor-mediated control of protein synthesis at developing synapses.

We demonstrate a rapid and complex effect of N-methyl-d-aspartate receptor (NMDAR) activation on synaptic protein synthesis in the superior colliculi of young rats. Within minutes of receptor activation, translation of alpha Ca2+/calmodulin dependent kinase II (alphaCamK II) was increased, whereas total protein synthesis was reduced. NMDAR activation also increased phosphorylation of eukaryotic elongation factor 2 (eEF2), a process known to inhibit protein translation by reducing peptide chain elongation. Low doses of cycloheximide, which reduce elongation rate independently of eEF2 phosphorylation, decreased overall protein synthesis but increased alphaCaMK II synthesis. These observations suggest that regulation of peptide elongation via eEF2 phosphorylation can link NMDAR activation to local increases in the synthesis of specific proteins during activity-dependent synaptic change.