scholarly journals Intrinsic Protein Kinase Activity in Mitochondrial Oxidative Phosphorylation Complexes

Biochemistry ◽  
2011 ◽  
Vol 50 (13) ◽  
pp. 2515-2529 ◽  
Author(s):  
Darci Phillips ◽  
Angel M. Aponte ◽  
Raul Covian ◽  
Robert S. Balaban
Keyword(s):  
Protein Kinase ◽  
Oxidative Phosphorylation ◽  
Kinase Activity ◽  
Protein Kinase Activity ◽  
Mitochondrial Oxidative Phosphorylation ◽  
Intrinsic Protein

Effect of Thrombin on Phosphorylation of Platelet Membrane Proteins

1976 ◽  
Vol 35 (03) ◽  
pp. 635-642 ◽  
Author(s):  
M Steiner
Keyword(s):  
Protein Kinase ◽  
Kinase Activity ◽  
Qualitative Change ◽  
Protein Kinase Activity ◽  
Protein Substrates ◽  
Phosphoprotein Phosphatase ◽  
Progressive Loss ◽  
Platelet Membranes ◽  
Endogenous Protein ◽  
Considerable Loss

SummaryThe effect of thrombin on the phosphorylating activity of platelet membranes was compared to that of trypsin. Preincubation of non-32P phosphorylated platelet membranes with or without either of these two enzymes resulted in a considerable loss of membrane protein kinase activity which was most severe when trypsin was used. Protein kinase activity and endogenous protein acceptors decreased in parallel. 32P-phosphorylated membranes showed a slow but progressive loss of label which was accelerated by trypsin. Thrombin under these conditions prevented the loss of 32P-phosphate. These results are interpreted to indicate a thrombin-induced destruction of a phosphoprotein phosphatase. The protein kinase activity of phosphorylated platelet membranes using endogenous or exogenous protein substrates showed a significant reduction compared to non-phosphorylated membranes suggesting a deactivation of protein kinase by phosphorylation of platelet membranes. Neither thrombin nor trypsin caused a qualitative change in the membrane polypeptides accepting 32P-phosphate but resulted in quantitative alterations of their ability to become phosphorylated.

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