Activation of multifunctional Ca2+/calmodulin-dependent kinase in intact hippocampal slices.
In vitro phosphorylation of multifunctional Ca2+/calmodulin-dependent protein kinase (CaM kinase) converts it to a form that is independent of Ca2+. We demonstrate that significant Ca(2+)-independent CaM kinase activity is present in untreated hippocampal slices. Two manipulations that produce a long-lasting enhancement of neuronal activity in hippocampal slices, elevated extracellular Ca2+ or depolarization with high K+, generate additional Ca(2+)-independent activity. This increase is dependent on extracellular Ca2+ and is correlated with an increased phosphorylation of CaM kinase. In contrast, CaM kinase in posterior pituitary, a brain structure that is not thought to be involved in memory-related processes, is not modulated by depolarization. These results suggest that the Ca(2+)-independent form of CaM kinase may modulate neuronal activity in the hippocampus.
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Department of Pharmacology, Stanford University School of Medicine, California 94305.
Schulman
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D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D004533:Egtazic Acid / Q000494:pharmacology; D004789:Enzyme Activation; D006624:Hippocampus / Q000187:drug effects / Q000201:enzymology* / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D009928:Organ Specificity; D010766:Phosphorylation; D010904:Pituitary Gland, Posterior / Q000201:enzymology; D011188:Potassium / Q000494:pharmacology; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D000001:Calcimycin; D004533:Egtazic Acid; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D011188:Potassium; D002118:Calcium