Kinetics of calcium and calmodulin-dependent protein kinase III from embryonic chicken leg muscle cells.
Embryonic chicken muscle cells (CELM) contain the calmodulin-dependent protein kinase that specifically phosphorylates eukaryotic elongation factor 2. The kinase requires Ca2+ and maximum activity in CELM was observed at 10 microM Ca2+. The ATP concentration required for half the maximum activity of CaM PKIII in CELM was calculated to be 0.15 mM. In CELM, dephosphorylation of eEF-2 was catalyzed by phosphoprotein phosphatase PP2A alone. The activity of PP2A was relatively low and the half-life of added phosphorylated eEF-2 was more than 15 min. Due to the low phosphoprotein phosphatase activity, inhibition of the PP2A activity by addition of okadaic acid had little effect on the eEF-2 phosphorylation kinetics.
Riis
B
B
Department of Zoological Cell Biology, Wenner-Grens Institute, Stockholm University, Sweden. Bent.Riis@sh.dk
Nygård
O
O
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002642:Chick Embryo; D054736:Elongation Factor 2 Kinase; D007700:Kinetics; D007866:Leg / Q000196:embryology; D018482:Muscle, Skeletal / Q000196:embryology / Q000201:enzymology*; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects
D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors; D000255:Adenosine Triphosphate; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D054736:Elongation Factor 2 Kinase; D010749:Phosphoprotein Phosphatases; D002118:Calcium