Polyclonal antisera to the phospholipid/Ca2+-dependent protein kinase have been used to study the distribution of the enzyme in identified neurons of several brain regions. The results indicated that the enzyme was concentrated in synaptic terminals of mossy fibers, Golgi II neurons and Purkinje neurons in the cerebellum, and in granule cell terminals in the hippocampus. These synapses have different physiological properties and utilize different neurotransmitters. Electron microscopic results indicated that the enzyme was concentrated in presynaptic terminals. Thus, the protein kinase may play a broad role in Ca2+-related events of the presynaptic terminal during neurotransmission. Light- and electron-microscopic immunocytochemical analysis also indicated that the enzyme was inside the nucleus concentrated in a region adjacent to the inner nuclear membrane, where it may play a role in the regulation of neuronal function.

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