TEMPORAL DIFFERENCES IN THE PHOSPHORYLATION STATE OF PRESYNAPTIC AND POSTSYNAPTIC PROTEIN-KINASE-C SUBSTRATES B-50 GAP-43 AND NEUROGRANIN DURING LONG-TERM POTENTIATION/

The phosphorylation state of two identified neural-specific protein ki nase C substrates (the presynaptic protein B-50 and the postsynaptic p rotein neurogranin) was monitored after the induction of long term pot entiation in the CA1 field of rat hippocampus slices by quantitative i mmunoprecipitation following P-92(i) labeling in the recording chamber . B-50 phosphorylation was increased from 10 to 60 min, but no longer at 90 min after long term potentiation had been induced, neurogranin p hosphorylation only at 60 min. increased phosphorylation was not found when long term potentiation was blocked with the N-methyl-D-aspartate receptor antagonist D-2-amino-5-phosphonovalerate, when only low freq uency stimulation was applied or tetanic stimulation failed to induce long term potentiation. Our data show that both B-50 and neurogranin p hosphorylation are increased following the induction of long term pote ntiation, thus providing strong evidence for pre- and postsynaptic pro tein kinase C activation during narrow, partially overlapping, time wi ndows after the induction of long term potentiation.