Cultured cerebellar granule cells were studied to determine if the excitatory neurotransmitter glutamate acting through the N-methyl-d-aspartate (NMDA) receptor could stimulate autophosphorylation of Ca2+/calmodulin-dependent protein kinase II (CaM-kinase II) to generate its Ca2+-independent form. Glutamate did elevate Ca2+-independent CaM-kinase II through autophosphorylation when granule cells were incubated in Mg2+-free buffer, and this response was potentiated by 1 μM glycine. Extracellular Ca2+ was required, and specific antagonists of the NMDA receptor blocked the response. These results support the hypothesis that postsynaptic Ca2+ influx through the NMDA receptor-gated ion channel, as occurs during induction of long-term potentiation, may convert CaM-kinase II to a constitutively active, Ca2+-independent form.
ASJC Scopus subject areas
- Molecular Biology
- Cellular and Molecular Neuroscience
- Cell Biology