Calcium/diacylglycerol-dependent protein kinase and its major 87-kilodalton protein substrate are differentially distributed in rat basal ganglia.

When brain tissue is subjected to subcellular fractionation, both calcium/diacylglycerol-dependent protein kinase (protein kinase C) and an 87-kilodalton (kDa) protein substrate for this enzyme are enriched in the crude nerve terminal fraction. The present study, using chemical and surgical lesions of neurons in the rat neostriatum and substantia nigra, has examined whether the 87-kDa protein is colocalized with protein kinase C in identified neurons and nerve terminals. Our results show that, in the basal ganglia, protein kinase C is highly enriched in local striatal neurons and the striatonigral fibers and terminals. In contrast, the 87-kDa protein appears to be widely and evenly distributed in both neuronal and nonneuronal cells. The 87-kDa protein may therefore mediate functions of protein kinase C not restricted to nerve terminals.