Differential effects of fatty acid and phospholipid activators on the catalytic activities of a structurally novel protein kinase from rat liver.
The lipid responsiveness of the structurally unique protein kinase, referred to as PAK-1, recently isolated from rat liver [(1994) J. Biol. Chem. 269, in press], is characterised by the high sensitivity (low micromolar) of its ribosomal S6(229-239) peptide kinase activity to both cardiolipin and the cis-unsaturated fatty acids and insensitivity to phosphatidylserine. Autophosphorylation of PAK-1 exhibited even greater sensitivity (submicromolar) to cardiolipin, but was relatively less affected by phosphatidylserine. Oleate, the most potent activator of PAK-1's peptide kinase activity was relatively ineffectual with autophosphorylation. These and other unusual characteristics, including high levels of basal catalytic activities, suggest a novel mechanism of regulation distinct from that of the protein kinase Cs.
Morrice
N A
NA
Russell Grimwade School of Biochemistry, University of Melbourne, Parkville, Vic., Australia.
Fecondo
J
J
Wettenhall
R E
RE
D000595:Amino Acid Sequence; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D005227:Fatty Acids / Q000494:pharmacology*; D008099:Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D010446:Peptide Fragments; D010743:Phospholipids / Q000494:pharmacology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D038601:Ribosomal Protein S6; D012269:Ribosomal Proteins / Q000378:metabolism
D005227:Fatty Acids; D010446:Peptide Fragments; D010743:Phospholipids; D038601:Ribosomal Protein S6; D012269:Ribosomal Proteins; D011494:Protein Kinases; C036447:protease activated kinase I