scholarly journals Binding of two fluorescent cAMP analogues to type I and II regulatory subunits of cAMP-dependent protein kinases

Author(s):  
Carla Mucignat-Caretta ◽  
Antonio Caretta
1991 ◽  
Vol 290 (2) ◽  
pp. 293-302 ◽  
Author(s):  
Noriko Takahashi ◽  
Charis Liapi ◽  
Wayne B. Anderson ◽  
Theodore R. Breitman

1990 ◽  
Vol 270 (1) ◽  
pp. 181-188 ◽  
Author(s):  
G Schwoch ◽  
B Trinczek ◽  
C Bode

Observation and quantification of the catalytic subunit C of cyclic AMP-dependent protein kinases by immuno-gold electron microscopy suggested a high concentration of cyclic AMP-dependent protein kinases in mitochondria from liver, kidney, heart and skeletal muscle, pancreas, parotid gland and brain cells. The position of gold particles pointed to a localization in the inner membrane/matrix space. A similar distribution was obtained by immunolocalization of the cyclic AMP-dependent protein kinase regulatory subunits RI and RII in liver, pancreas and heart cells. The results indicated the presence of both the type I and the type II cyclic AMP-dependent protein kinases in mitochondria of hepatocytes, and the preferential occurrence of the type I protein kinase in mitochondria from exocrine pancreas and heart muscle. The immunocytochemical results were confirmed by immunochemical determination of cyclic AMP-dependent protein kinase subunits in fractionated tissues. Determinations by e.l.i.s.a. of the C-subunit in parotid gland cell fractions indicated about a 4-fold higher concentration of C-subunit in the mitochondria than in a crude 1200 g supernatant. Immunoblot analysis of subfractions from liver mitochondria supported the localization in situ of cyclic AMP-dependent protein kinases in the inner membrane/matrix space and suggested that the type I enzyme is anchored by its regulatory subunit to the inner membrane. In accordance with the immunoblot data, the specific activity of cyclic AMP-dependent protein kinase measured in the matrix fraction was about twice that measured in whole mitochondria. These findings indicate the importance of cyclic AMP-dependent protein kinases in the regulation of mitochondrial functions.


1994 ◽  
Vol 99 (1) ◽  
pp. 103-110 ◽  
Author(s):  
M.Ben Abdelkhalek ◽  
M.F. Breton ◽  
D. Feliers ◽  
B. Haye ◽  
M. Pavlovic-Hournac

1979 ◽  
Author(s):  
R.J. Haslam ◽  
J.E.B. Fox ◽  
S.E. Salama ◽  
J.A. Lynham

The relationships between the phosphorylation of specific platelet polypeptides and platelet function were studied using washed human platelets labelled by preincubation with [32p] Pi. Platelet polypeptides were separated by SDS-PAGE and 32P incorporation into them determined by autoradiography. Whereas induction of platelet aggregation alone did not affect protein phosphorylation, induction of the release reaction increased 3P incorporation into several polypeptides (P75,P47,P40,P27,P20,P19), including the P-light chain of platelet myosin (P20). These changes were inhibited by drugs that blocked Ca2 movements and may be due to activation of Ca2+-dependent protein kinases. Compounds that inhibited platelet function by increasing cyclic AMP (e.g. PCE1) also suppressed these reactions but, in addition, increased phosphorylation of other polypeptides (P50,P49,P36,P24,P22). Type I and Type II cyclic AMP-dependent protein kinases were present in platelets and may mediate Che latter effects of cyclic AMP. Subcellular fractionation of 32p-labelled platelets that had been exposed to PCE1 showed that P24 was present in membranes that could take up Ca2+ by an ATP-dependent mechanism. Membranes from PCE1-treated platelets took up Ca2+ more rapidly than control membranes. Thus, the cyclic AMP-dependent phosphorylation of P24 may stimulate the removal of Ca2+ from platelet cytosol and suppress Ca2+-dependent phosphorylation reactions necessary for release of granule constituents.


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