Phosphorylation of phospholamban in aortic smooth muscle cells and heart by calcium/calmodulin-dependent protein kinase II.
Phospholamban is a negative regulator of the sarcoplasmic reticulum Ca(2+)-pumping ATPase. Phosphorylation of phospholamban activates the ATPase and decreases the level of cytosolic calcium. Phospholamban is phosphorylated in heart by cAMP-dependent protein kinase, cGMP-dependent protein kinase and calcium/calmodulin-dependent protein kinase II (CM-kinase-II) and in smooth muscle cells by cGMP-dependent protein kinase. In contrast to heart muscle, phospholamban is poorly phosphorylated by CM-kinase-II in extracts of rat aortic smooth muscle cells. Rat aorta phospholamban amino acid sequence was identical to dog heart. The peptide substrate specificity of CM-kinase-II from rat aorta was the same as that from rat heart. The lack of phosphorylation of rat aorta phospholamban by the CM-kinase-II appears to result from the relatively low abundance of phospholamban in smooth muscle.
St Vincent's Institute of Medical Research, Fitzroy, Vic., Australia.
W
W
Chen
M
M
Lah
P J
PJ
Robinson
B E
BE
Kemp
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001013:Aorta, Thoracic; D001483:Base Sequence; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*; D017931:DNA Primers; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000201:enzymology*; D009206:Myocardium / Q000201:enzymology*; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013379:Substrate Specificity; D000099211:Phospholamban
D000251:Adenosine Triphosphatases; D002135:Calcium-Binding Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D017931:DNA Primers; D000099211:Phospholamban