Hormone-Sensitive Adenylate Cyclase Activity as a Marker to Distinguish between Blood Sinusoidal and Bile Canalicular Surface Fragments in Rat Liver Plasma-Membrane Subfractions

1974 ◽  
Vol 2 (3) ◽  
pp. 407-408 ◽  
Author(s):  
MARTIN H. WISHER ◽  
W. HOWARD EVANS
Keyword(s):  
Plasma Membrane ◽  
Adenylate Cyclase ◽  
Rat Liver ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Liver Plasma Membrane ◽  
Hormone Sensitive

Down-regulation in vivo of PGE receptors and adenylate cyclase stimulation

1980 ◽  
Vol 239 (1) ◽  
pp. E75-E80
Author(s):  
R. P. Robertson ◽  
K. R. Westcott ◽  
D. R. Storm ◽  
M. G. Rice
Keyword(s):  
Plasma Membrane ◽  
Adenylate Cyclase ◽  
Binding Affinity ◽  
Membrane Receptors ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Down Regulation ◽  
Liver Plasma Membrane ◽  
Plasma Membrane Receptors

Down-regulation in vivo of liver plasma membrane receptors for prostaglandin E (PGE) was investigated in Sprague-Dawley rats using the 16,16-dimethyl analogue of PGE2, This analogue was used for subcutaneous injections because it escapes the rapid pulmonic degradation characteristic of PGE and was recognized well by liver plasma membrane receptors. Following treatment with the analogue, the concentration of PGE receptors was significantly decreased (-37%, P less than 0.001), but the binding affinity was not altered. There was no evidence for carry-through of the analogue into the isolated plasma membrane preparation. It was also demonstrated that GTP decreased the binding affinity between PGE and its receptor. Down-regulation of receptor concentration was associated with a significant decrease (P less than 0.001) in PGE1-stimulated plasma membrane adenylate cyclase activity. These data provide the novel demonstration that rat liver plasma membrane receptor for PGE can be down-regulated in vivo and that this causes a corresponding decrease in PGE-induced plasma membrane adenylate cyclase activity.

scholarly journals Lysophosphatidylcholines can modulate the activity of the glucagon-stimulated adenylate cyclase from rat liver plasma membranes

1979 ◽  
Vol 178 (1) ◽  
pp. 217-221 ◽  
Author(s):  
M D Houslay ◽  
R W Palmer
Keyword(s):  
Adenylate Cyclase ◽  
Rat Liver ◽  
Plasma Membranes ◽  
Hormone Receptors ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Liver Plasma Membranes ◽  
Rat Liver Plasma Membranes ◽  
Increased Sensitivity

1. Synthetic lysophosphatidylcholines inhibit the glucagon-stimulated adenylate cyclase activity of rat liver plasma membranes at concentrations two to five times lower than those needed to inhibit the fluoride-stimulated activity. 2. Specific 125I-labelled glucagon binding to hormone receptors is inhibited at concentrations similar to those inhibiting the fluoride-stimulated activity. 3. At concentrations of lysophosphatidylcholines immediately below those causing inhibition, an activation of adenylate cyclase activity or hormone binding was observed. 4 These effects are essentially reversible. 5. We conclude that the increased sensitivity of glucagon-stimulated adenylate cyclase to inhibition may be due to the lysophosphatidylcholines interfering with the physical coupling between the hormone receptor and catalytic unit of adenylate cyclase. 6. We suggest that, in vivo, it is possible that lysophosphatidylcholines may modulate the activity of adenylate cyclase only when it is in the hormone-stimulated state.

Effects of benzyl alcohol on PTH receptor-adenylate cyclase system of canine kidney

1985 ◽  
Vol 248 (1) ◽  
pp. E31-E35
Author(s):  
K. J. Martin ◽  
C. L. McConkey ◽  
T. J. Stokes
Keyword(s):  
Enzyme Activity ◽  
Adenylate Cyclase ◽  
Benzyl Alcohol ◽  
Membrane Fluidity ◽  
Phospholipid Composition ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Adenylate Cyclase System ◽  
Hormone Sensitive ◽  
Canine Kidney

In many systems, perturbations of membrane architecture by changes of lipid and phospholipid composition have been shown to alter the activity of membrane-bound enzymes. The present studies examined the effect of benzyl alcohol, an agent that has been shown to increase membrane fluidity, on the parathyroid hormone (PTH)-sensitive adenylate cyclase system of canine kidney. Benzyl alcohol progressively increased basal adenylate cyclase activity up to fourfold and maximal enzyme activity in the presence of PTH, GTP, guanylimidodiphosphate, and sodium fluoride by four- to sixfold. In the presence of 20 mM Mn2+ (no Mg2+), conditions under which enzyme activity is devoid of influence of guanine nucleotides or hormones, benzyl alcohol was without effect. PTH binding was increased by 25% in the presence of benzyl alcohol without a change in binding affinity. Fluorescent polarization studies using diphenylhexatriene showed a decrease in fluorescence anisotropy in the presence of benzyl alcohol. The results suggest that benzyl alcohol facilitates the interaction of the components of the adenylate cyclase system, presumably by increasing membrane fluidity. Alterations of membrane fluidity may be a potent means of regulating hormone sensitive adenylate cyclase activity.

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