Ca2+ and phospholipid-dependent protein kinase activity in rat cerebral hemispheres.

Ca2+/phospholipid-dependent protein kinase (PKC) activity was found to be asymmetrically distributed between the two cerebral hemispheres of rat brain, whereas basal protein phosphorylation was not lateralized. The left cerebral hemisphere (LCH) displayed about 50% more PKC activity in synaptosomal fractions than the right cerebral hemisphere (RCH). Polyacrylamide gel electrophoresis, autoradiography and quantitation of radioactivity in individual protein bands showed that the phosphate acceptors with major interhemispheric differences were proteins of more than 50 kDa. Cerebral lateralization was also apparent in the pattern of PKC inhibition mediated by phospholipid-interacting drugs: chlorpromazine and polymyxin B depressed activity more profoundly in LCH. A covalent protein modification usually associated with neurotransmitter receptor activation is thus unevenly distributed in rodent brain.