title: Palmitoylcarnitine modulates interaction between protein kinase C betaII and its receptor RACK1.
abstract: Palmitoylcarnitine, known to promote differentiation of neuroblastoma NB-2a cells as well as to inhibit protein kinase C (PKC) activity and to decrease phorbol ester binding, was shown previously to diminish the amount of complex formed between PKCdelta and its substrate GAP-43. In the present work we studied the effect of palmitoylcarnitine on the interaction between PKCbetaII and its receptor RACK1. Palmitoylcarnitine was found to decrease autophosphorylation of PKCbetaII on serine in a concentration-dependent manner and to decrease the amount of PKCbetaII/RACK1 complex. The effect of palmitoylcarnitine on cellular localization was found to be dependent on the presence of ATP; palmitoylcarnitine lowered the amount of PKCbetaII in cytosol and decreased the amount of PKCbetaII-RACK1 complex in membrane in the absence of ATP. Palmitoylcarnitine also reversed the effect of phorbol ester on the increase in the amount of PKCbetaII in membrane. Palmitoylcarnitine binds to PKCbetaII through hydrophobic interactions, although acylation of PKCbetaII by the palmitate moiety has been excluded. The presence of palmitoylcarnitine did not have any additive effect on the diminution of PKCbetaII-RACK1 complex formation in the presence of a RACK1-binding peptide from within the C2 region of PKCbetaII. These results rather exclude a possibility of interaction of palmitoylcarnitine with the C2 domain and suggest a possible interaction with the V5 domain and a conformational change affecting the C1 region.
authors.affiliation: Nencki Institute of Experimental Biology, Warsaw, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Sobiesiak-Mirska
authors.forename: Katarzyna A
authors.initials: KA
authors.lastname: Nałecz
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D002458:Cell Fractionation; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D009363:Neoplasm Proteins / Q000378:metabolism*; D010172:Palmitoylcarnitine / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism*; D064546:Protein Kinase C beta; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
chemical_list: D004791:Enzyme Inhibitors; D009363:Neoplasm Proteins; C419368:RACK1 protein, human; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface; D010172:Palmitoylcarnitine; D000255:Adenosine Triphosphate; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D019204:GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate