Activation of protein kinase C by myristate and its requirements of Ca2+ and phospholipid.
Myristate (C14:0) was found to significantly activate partially purified rat brain Ca(2+)- and phospholipid-dependent protein kinase (PKC). The Ka value, the concentration needed for half maximum activation, for C14:0 in the presence of 1 microM Ca2+ and 20 microM phosphatidylserine (PS) was 20 microM. This activation required Ca2+ and acidic phospholipid and was associated with a decreased Ka for Ca2+ of the enzyme to 10 microM in an analogous fashion as dioleoylglycerol (DO) or phorbol myristate acetate (PMA). The phospholipid requirement for the activation was concentration dependent and was inhibited by 1-(5-isoquinolinesulfonyl)-methylpiperazine dihydrochloride (H-7), a inhibitor of this enzyme. The concentration of H-7 required for half inhibition of the enzyme was about 15 microM and maximum inhibition was about 75%. The concentration profile of cytoplasmic proteins phosphorylated by C14:0-activated PKC was similar to that by PMA-activated PKC. The 47 kDa protein of guinea pig neutrophil was also phosphorylated by the C14:0-activated PKC. It is further discussed whether PKC can function as signal transduction for stimulus-mediated generation of superoxide in neutrophils.
Iwata
M
M
Department of Pharmacology, Okayama University Medical School, Japan.
Edashige
K
K
Saeki
K
K
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000201:enzymology; D002118:Calcium / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007546:Isoquinolines / Q000494:pharmacology; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism*; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D007546:Isoquinolines; D009419:Nerve Tissue Proteins; D010743:Phospholipids; D010879:Piperazines; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D009247:NADH, NADPH Oxidoreductases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium