scholarly journals Characterization of the protein kinase activities of human platelet supernatant and particulate fractions

1984 ◽  
Vol 218 (2) ◽  
pp. 285-294 ◽  
Author(s):  
S E Salama ◽  
R J Haslam

After human platelets were lysed by freezing and thawing in the presence of EDTA, about 35% of the total cyclic AMP-dependent protein kinase activity was specifically associated with the particulate fraction. In contrast, Ca2+-activated phospholipid-dependent protein kinase was found exclusively in the soluble fraction. Photoaffinity labelling of the regulatory subunits of cyclic AMP-dependent protein kinase with 8-azido-cyclic [32P]AMP indicated that platelet lysate contained a 4-fold excess of 49 000-Da RI subunits over 55 000-Da RII subunits. The RI and RII subunits were found almost entirely in the particulate and soluble fractions respectively. Chromatography of the soluble fraction on DEAE-cellulose demonstrated a single peak of cyclic AMP-dependent activity with the elution characteristics and regulatory subunits characteristic of the type-II enzyme. A major enzyme peak containing Ca2+-activated phospholipid-dependent protein kinase was eluted before the type-II enzyme, but no type-I cyclic AMP-dependent activity was normally observed in the soluble fraction. The particulate cyclic AMP-dependent protein kinase and associated RI subunits were solubilized by buffers containing 0.1 or 0.5% (w/v) Triton X-100, but not by extraction with 0.5 M-NaCl, indicating that this enzyme is firmly membrane-bound, either as an integral membrane protein or via an anchor protein. DEAE-cellulose chromatography of the Triton X-100 extracts demonstrated the presence of both type-I cyclic AMP-dependent holoenzyme and free RI subunits. These results show that platelets contain three main protein kinase activities detectable with histone substrates, namely a membrane-bound type-I cyclic AMP-dependent enzyme, a soluble type-II cyclic AMP-dependent enzyme and Ca2+-activated phospholipid-dependent protein kinase, which was soluble in lysates containing EDTA.

1978 ◽  
Vol 175 (2) ◽  
pp. 367-375 ◽  
Author(s):  
A M Malkinson ◽  
A J Gharrett ◽  
L Hogy

1. DEAE-cellulose chromatography of mouse brain cytosol indicated the presence of only the type II isoenzyme of cyclic AMP-dependent protein kinase. Mouse heart cytosol contained approximately equal amounts of the type I and type II isoenzymes. 2. Both brain and heart type II isoenzymes reassociated after a transient exposure to cyclic AMP, but the heart type I isoenzyme remained dissociated. 3. Elution of brain cytosol continuously exposed to cyclic AMP resolved multiple peaks of protein kinase and cyclic AMP-binding activities. A single peak of kinase and multiple peaks of cyclic AMP-binding activities were found under the same conditions with heart cytosol. Various control experiments suggested that the heterogeneity within the brain type II isoenzymic class had not been caused by proteolysis. 4. Kinetic experiments with unfractionated brain cytosol showed that the binding of cyclic AMP, the dissociation of cyclic AMP from protein and the rate of heat denaturation of the cyclic AMP-binding activity gave results consistent with the presence of multiple binding species. 5. It concluded that the type II isoenzymic peak obtained by DEAE-cellulose chromatography of mouse brain cytosol represents a class of enzymes containing multiple regulatory and catalytic subunits. The two heart cytosol isoenzymes contain a common catalytic subunit. The degree of protein kinase ‘microheterogeneity”, defined as the presence of multiple regulatory and/or catalytic subunits within a single isoenzymic class, appears to be tissue-specific.


1982 ◽  
Vol 203 (3) ◽  
pp. 583-592 ◽  
Author(s):  
Ramesh C. Bhalla ◽  
Ram V. Sharma ◽  
Ramesh C. Gupta

Myosin light-chain kinase was purifed from bovine carotid artery. Approx. 90% of myosin kinase was extracted in the supernatant fraction with buffer containing EDTA during myofibril preparation. The soluble fraction yielded two distinct peaks on DEAE-Sephacel chromatography. Peak I was eluted at a conductance of 11–12mmho and was completely dependent on Ca2+–calmodulin for its activity. Peak II was eluted at a conductance of 13–14mmho and showed approx. 15% Ca2+-independent activity. The myosin kinases I and II were further purified by affinity chromatography by using calmodulin coupled to Sepharose 4B, which resulted in 960-and 650-fold purification of type I and type II kinases respectively. Myosin kinase II activity was completely Ca2+-dependent after affinity chromatography on the calmodulin–Sepharose column. Myosin kinases I and II were phosphorylated by cyclic AMP-dependent protein kinase. In the presence of bound calmodulin 0.5–0.7mol of phosphate was incorporated/mol of myosin kinases I and II. On the other hand, in the absence of bound calmodulin 1–1.4mol of phosphate was incorporated/mol of kinases I and II. Phosphorylation in the absence of calmodulin significantly decreased the myosin kinase activity of both enzymes, and the decrease in myosin kinase activity was due to a 3–5-fold increase in the amount of calmodulin required for half-maximal stimulation of both type I and type II kinases. The regulation of myosin kinase activity by cyclic AMP-dependent phosphorylation would suggest that β-adrenergic-mediated relaxation of vascular smooth muscle may be partly due to the direct interaction of cyclic AMP at the site of contractile proteins.


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.


1986 ◽  
Vol 238 (2) ◽  
pp. 341-344 ◽  
Author(s):  
J G Church ◽  
J B Derdemezi ◽  
S Yuan ◽  
A K Sen

Highly purified sarcolemma from dog and pig cardiac muscle has been shown to contain significant activities of a membrane-bound cyclic AMP-dependent protein kinase. In addition, these membranes undergo endogenous phosphorylation when incubated with Mg2+ and [gamma-32P]ATP. By comparing 32P-labelled patterns obtained with [gamma-32P]ATP and the photoaffinity label 8-azidoadenosine 3′:5′-[32P]monophosphate (8-azido-cyclic [32P]AMP), we have demonstrated that, whereas the major kinase isoenzyme in dog sarcolemma was Type II, that in the pig membrane was the Type I isoenzyme.


2008 ◽  
Vol 8 (5) ◽  
pp. 1016-1028 ◽  
Author(s):  
Thin Thin Aye ◽  
Shabaz Mohammed ◽  
Henk W. P. van den Toorn ◽  
Toon A. B. van Veen ◽  
Marcel A. G. van der Heyden ◽  
...  

Nature ◽  
1977 ◽  
Vol 268 (5615) ◽  
pp. 63-64 ◽  
Author(s):  
CRAIG V. BYUS ◽  
GARY R. KLIMPEL ◽  
DAVID O. LUCAS ◽  
DIANE HADDOCK RUSSELL

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