title: Physiological role for phosphatidic acid in the translocation of the novel protein kinase C Apl II in Aplysia neurons.
abstract: In Aplysia californica, the serotonin-mediated translocation of protein kinase C (PKC) Apl II to neuronal membranes is important for synaptic plasticity. The orthologue of PKC Apl II, PKCepsilon, has been reported to require phosphatidic acid (PA) in conjunction with diacylglycerol (DAG) for translocation. We find that PKC Apl II can be synergistically translocated to membranes by the combination of DAG and PA. We identify a mutation in the C1b domain (arginine 273 to histidine; PKC Apl II-R273H) that removes the effects of exogenous PA. In Aplysia neurons, the inhibition of endogenous PA production by 1-butanol inhibited the physiological translocation of PKC Apl II by serotonin in the cell body and at the synapse but not the translocation of PKC Apl II-R273H. The translocation of PKC Apl II-R273H in the absence of PA was explained by two additional effects of this mutation: (i) the mutation removed C2 domain-mediated inhibition, and (ii) the mutation decreased the concentration of DAG required for PKC Apl II translocation. We present a model in which, under physiological conditions, PA is important to activate the novel PKC Apl II both by synergizing with DAG and removing C2 domain-mediated inhibition.
authors.affiliation: Department of Neurology and Neurosurgery, McGill University, Montreal Neurological Institute, Montreal, Quebec H3A 2B4, Canada.
authors.forename: Carole A
authors.initials: CA
authors.lastname: Farah
authors.forename: Ikue
authors.initials: I
authors.lastname: Nagakura
authors.forename: Daniel
authors.initials: D
authors.lastname: Weatherill
authors.forename: Xiaotang
authors.initials: X
authors.lastname: Fan
authors.forename: Wayne S
authors.initials: WS
authors.lastname: Sossin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001048:Aplysia / Q000201:enzymology*; D002460:Cell Line; D004075:Diglycerides / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008954:Models, Biological; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000378:metabolism; D009475:Neurons, Afferent / Q000187:drug effects / Q000201:enzymology*; D010712:Phosphatidic Acids / Q000378:metabolism*; D054801:Phosphoinositide Phospholipase C / Q000378:metabolism; D010739:Phospholipase D / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D016415:Sequence Alignment; D012701:Serotonin / Q000494:pharmacology
chemical_list: C011439:1,2-diacylglycerol; D004075:Diglycerides; D007527:Isoenzymes; D050505:Mutant Proteins; D010712:Phosphatidic Acids; C044295:1,2-dioctanoylglycerol; D012701:Serotonin; C121046:Apl II protein kinase C; D011493:Protein Kinase C; D054801:Phosphoinositide Phospholipase C; D010739:Phospholipase D