Preincubation of intact fetal rat brain neurons in culture with 32Pi results in the incorporation of 32Pi into about 20 specific proteins. Upon stimulation by electrical field stimulation or by K+-induced depolarization, highly significant calcium-dependent increase in phosphorylation of a protein of app. Mr 43 000 and decrease in phosphorylation of an app. Mr 55 000 protein occur. These changes can be attributed to the entry of Ca2+ into the cellular cytoplasm since they can occur upon selective permeabilization of the cell membrane to Ca2+ by the Ca2+-ionophore A23187 and are not observed upon stimulation of the cells in the presence of the Ca2+ channel blocker D-600. These data suggest that these phosphoproteins may be involved in the regulation of processes underlying neurotransmitter release.
- Phosphorylation Brain Neuron Neurotransmitter release