Figure 3.

Phospho-eEF2 is induced by NMDA/GLUT stimulation in preparations enriched in functional synaptic contacts. (A) Densitometric measurement of immunoblots detecting NMDAR-induced phospho-eEF2. Synaptoneurosomes received NMDA/GLUT stimulation with or without prior preincubation with 60 μM AP5. NMDA/GLUT stimulation alone resulted in a 7-fold increase in phospho-eEF2 compared with AP5 control. Examples shown are representative of three independent determinations. NMDA/GLUT stimulation without AP5 preincubation produced robust eEF2 phosphorylation (lane 1). However, NMDA/GLUT stimulation after AP5 preincubation resulted in low levels of eEF2 phosphorylation (lane 2). (B) Electron micrographs show that synaptoneurosomes are enriched in synaptic contacts. Arrows delineate presynaptic extent of synaptic apposition. Similar results were obtained from three independent synaptoneurosome preparations, and synaptic density is comparable to that reported previously (19).