scholarly journals Uncoupling of alpha-adrenoceptor-mediated inhibition of human platelet adenylate cyclase by N-ethylmaleimide.

1982 ◽  
Vol 257 (6) ◽  
pp. 2829-2833
Author(s):  
K H Jakobs ◽  
P Lasch ◽  
M Minuth ◽  
K Aktories ◽  
G Schultz
Keyword(s):  
Adenylate Cyclase ◽  
Human Platelet ◽  
Alpha Adrenoceptor

Effect of Novel 7β-Derivatives of Forskolin upon Human Platelet Adenylate Cyclase System

Planta Medica ◽  
1988 ◽  
Vol 54 (01) ◽  
pp. 4-6 ◽  
Author(s):  
E. Seguin ◽  
N. Ferry ◽  
J. Hanoune ◽  
M. Koch
Keyword(s):  
Adenylate Cyclase ◽  
Human Platelet ◽  
Adenylate Cyclase System ◽  
Derivatives Of

scholarly journals Evidence for regulation of human platelet adenylate cyclase by phosphorylation. Inhibition by ATP and guanosine 5′-[β-thio]diphosphate occur by distinct mechanisms

1991 ◽  
Vol 276 (3) ◽  
pp. 621-630 ◽  
Author(s):  
I A Wadman ◽  
R W Farndale ◽  
B R Martin
Keyword(s):  
Creatine Kinase ◽  
Adenylate Cyclase ◽  
Human Platelet ◽  
Binding Protein ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Phosphoryl Transfer ◽  
Activation Process ◽  
Gtp Binding Protein ◽  
Gtp Binding

1. Incubation of human platelet membranes with guanosine 5′-[beta gamma-imido]triphosphate (p[NH]ppG) causes a time-dependent increase in the activation of adenylate cyclase due to Gs (the stimulatory GTP-binding protein). Forskolin enhances adenylate cyclase activity but does not interfere with the process of activation. The activation follows first-order kinetics in both the presence and the absence of the assay components. 2. ATP in the presence or the absence of an ATP-regenerating system of phosphocreatine and creatine kinase inhibits activation. 3. Hydrolysis of ATP to ADP does not lead to receptor-mediated inhibition of adenylate cyclase acting via Gi (the inhibitory GTP-binding protein). The ADP analogue adenosine 5′-[beta-thio]diphosphate (ADP[S]) does not inhibit the activation process. 4. Phosphocreatine alone inhibits adenylate cyclase activation at concentrations above 1 mM. 5. Inhibition by phosphocreatine is not due to the chelation of free Mg2+ ions. 6. Inhibition by ATP and the other assay components occurs throughout the activation process, decreasing both the rate of activation and the maximum activity obtained. 7. Maximal activation of adenylate cyclase after prolonged incubation with p[NH]ppG slowly reverses in the presence of the assay components. 8. A 10-fold excess of the GDP analogue guanosine 5′-[beta-thio]diphosphate (GDP[S]) over p[NH]ppG inhibits the activation process completely, at all stages of the time course. 9. Preincubations in the presence and absence of ATP, cyclic AMP, phosphocreatine and creatine kinase show equal sensitivity to increasing GDP[S] concentration. These data show that the inhibition observed in the presence of ATP is not due to endogenous or contaminating guanine nucleotides, and suggest that phosphoryl transfer may regulate adenylate cyclase activity.

Calmodulin regulation of adenylate cyclase activity in human platelet membranes

Cell Calcium ◽  
1986 ◽  
Vol 7 (4) ◽  
pp. 261-273 ◽  
Author(s):  
George Y. Grigorian ◽  
Therese J. Resink ◽  
Susanne Stucki ◽  
Fritz R. Bühler
Keyword(s):  
Adenylate Cyclase ◽  
Human Platelet ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Platelet Membranes

scholarly journals The antagonism by BW A868C of PGD2 and BW245C activation of human platelet adenylate cyclase

1989 ◽  
Vol 96 (2) ◽  
pp. 301-306 ◽  
Author(s):  
D.G. Trist ◽  
B.A. Collins ◽  
J. Wood ◽  
M.G. Kelly ◽  
A.D. Robertson
Keyword(s):  
Adenylate Cyclase ◽  
Human Platelet

Activation of human platelet adenylate cyclase by a bovine sperm component

1983 ◽  
Vol 756 (3) ◽  
pp. 369-375 ◽  
Author(s):  
Karl H. Jakobs ◽  
Roger A. Johnson ◽  
Günter Schultz
Keyword(s):  
Adenylate Cyclase ◽  
Human Platelet ◽  
Bovine Sperm

Prostaglandins (PG) Inhibit Human Platelet Aggregation by PG Receptor Antagonism as well as Adenylate Cyclase Stimulation

1979 ◽  
Author(s):  
D.E. MacIntyre ◽  
E.W. Salzman
Keyword(s):  
Platelet Aggregation ◽  
Adenylate Cyclase ◽  
Human Platelet ◽  
High Ratio ◽  
Receptor Antagonism ◽  
Human Platelet Aggregation ◽  
Alkyl Groups ◽  
Low Concentrations ◽  
Alkyl Substitution ◽  
Adenylate Cyclase Stimulation

11-Deoxy and/or 15 or 16 alkyl substitution confer platelet aggregating activity to bis-enoic PG's: e.g., 11-deoxy-PGE2 (threshold (T)-5μM); ll-deoxy-15(S)-15-methyl-PGE2 (T=0.1μM);ll-deoxy-15(S)-16-methyl-PGE2(T=0.1μM). Responses induced by such PG’s mimic those induced by PGH2 and PGH2 analogues (e.g., U44069). N0164 competitively inhibits aggregation induced by PG’s and suppresses “secondary” responses induced by low concentrations of ADP or arachidonic acid, suggesting involvement of a specific PG stimulatory receptor in platelet aggregation. We compared non-aggregatory PG’s as inhibitors of pri mary aggregation induced by ADP or U44069. PG’s containing 11-deoxy and/or 16-alkyl groups selectively inhibited aggregation induced by U44069. Mean I50 values (n-4) against ADP and U44069 respectively were PGA2 (>100μM; 0.3μM); PGB2 (>100μM; 5μM); PGD2 (6nM; 2nM); PGE1(10nM; 5nM); 11-deoxy PGE1 (60μM; 2μM); ll-deoxy-15-(R)-16-methyl (100μM; 2μM); 13,14-dihydro-16-methyl-PGE2 methyl ester(750nM; 15nM). A low ADP: 406 I50 ratio (e.g., PGD2) indicates that inhibition is mainly due to adenylate cyclase stim ulation, and a high ratio (e.g., PGA2) that inhibition is mainly due to PG receptor antagonism. We have demonstrated a PG stimulatory receptor on the platelet, and its involvement in “secondary” aggregation. PG’s inhibit aggregation by combining with this receptor and/or by stimulating adenylate cyclase.

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