Temperature effects on adenylate cyclase activity and fluidity of bovine adrenal cortex plasma membranes

1986 ◽  
Vol 14 (6) ◽  
pp. 1011-1012 ◽  
Author(s):  
BÉATRICE De FORESTA ◽  
MONIQUE ROGARD ◽  
JACQUES GALLAY
Keyword(s):  
Adenylate Cyclase ◽  
Adrenal Cortex ◽  
Temperature Effects ◽  
Plasma Membranes ◽  
Cyclase Activity ◽  
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.

scholarly journals Elevated membrane cholesterol concentrations inhibit glucagon-stimulated adenylate cyclase

1983 ◽  
Vol 210 (2) ◽  
pp. 437-449 ◽  
Author(s):  
A D Whetton ◽  
L M Gordon ◽  
M D Houslay
Keyword(s):  
Fatty Acid ◽  
Adenylate Cyclase ◽  
Spin Probe ◽  
Plasma Membranes ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Cholesterol Concentration ◽  
Lipid Phase ◽  
Lipid Order ◽  
Liver Plasma Membranes

A method was devised which increases the cholesterol concentration of rat liver plasma membranes by exchange from cholesterol-rich liposomes at low temperature (4 degrees C). When the cholesterol concentration of liver plasma membranes is increased, there is an increase in lipid order as detected by a decrease in mobility of an incorporated fatty acid spin probe. This is accompanied by an inhibition of adenylate cyclase activity. The various ligand-stimulated adenylate cyclase activities exhibit different sensitivities to inhibition by cholesterol, with inhibition of glucagon-stimulated greater than fluoride-stimulated greater than basal activity. The bilayer-fluidizing agent benzyl alcohol is able to reverse the inhibitory effect of cholesterol on adenylate cyclase activity in full. The thermostability of fluoride-stimulated cyclase is increased in the cholesterol-rich membranes. Elevated cholesterol concentrations abolish the lipid-phase separation occurring at 28 degrees C in native membranes as detected by an incorporated fatty acid spin probe. This causes Arrhenius plots of glucagon-stimulated adenylate cyclase activity to become linear, rather than exhibiting a break at 28 degrees C. It is suggested that the cholesterol contents of both halves of the bilayer are increased by the method used and that inhibition of adenylate cyclase ensues, owing to the increase in lipid order and promotion of protein-protein and specific cholesterol-phospholipid interactions.

scholarly journals The activity of glucagon-stimulated adenylate cyclase from rat liver plasma membranes is modulated by the fluidity of its lipid environment

1978 ◽  
Vol 174 (1) ◽  
pp. 179-190 ◽  
Author(s):  
I Dipple ◽  
M D Houslay
Keyword(s):  
Adenylate Cyclase ◽  
Benzyl Alcohol ◽  
Plasma Membranes ◽  
Break Point ◽  
Alcohol Concentration ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Lipid Phase ◽  
Glucagon Receptor ◽  
Arrhenius Plots

1. The local anaesthetic benzyl alcohol progressively activated glucagon-stimulated adenylate cyclase activity up to a maximum at 50 mM-benzyl alcohol. Further increases in benzyl alcohol concentration inhibited the activity. The fluoride-stimulated adenylate cyclase activity was similarly affected except for an inhibition of activity occurring at low benzyl alcohol concentrations (approx. 10 mM. 2. The fluoride-stimulated adenylate cyclase activity of a solubilized enzyme preparation was unaffected by any of the benzyl alcohol concentrations tested. 3. Increases in 3-phenylpropan-1-ol and 5-phenylpentan-1-ol concentrations progressively activated both the fluoride- and glucagon-stimulated adenylate cyclase activities up to a maximum, above which further increases in alcohol concentration inhibited the activities. 4. The ‘break’ points in Arrhenius plots of glucagon-stimulated adenylate cyclase activity in native plasma membranes, and in plasma membranes fused with synthetic dimyristoyl phosphatidylcholine so as to constitute 60% of the total lipid pool, were decreased by approx. 6 degrees C by addition of 40 mM-benzyl alcohol. This was accompanied by a fall in the associated activation energies. 6. Arrhenius plots of fluoride-stimulated adenylate cyclase activity in the presence and absence of 40 mM-benzyl alcohol were linear, although addition of benzyl alcohol caused a dramatic decrease in the associated activation energy of the reaction. 7. 5′-Nucleotidase activity was stimulated by benzyl alcohol, and the ‘break’ point in the Arrhenius plot of its activity was decreased by about 6 degrees C by addition of 40 mM-benzyl alcohol to the assay. 8. It is suggested that benzyl alcohol effects a fluidization of the bilayer, which is clearly demonstrated by its ability to lower the temperature of a lipid phase separation occurring at 28 degrees C in the outer half of the bilayer to around 22 degrees C. The increase in bilayer fluidity relieves a physical constraint on the membrane-bound adenylate cyclase, activating the enzyme. 9. The various inhibition phenomena are discussed in detail, together with the suggestion that the interaction between the uncoupled catalytic unit of adenylate cyclase and the lipids of the bilayer is altered on its physical coupling to the glucagon receptor.

EFFECT OF GUANYL NUCLEOTIDES ON PARATHYROID HORMONE-RESPONSIVE ADENYLATE CYCLASE IN CHICK KIDNEY

1976 ◽  
Vol 69 (3) ◽  
pp. 401-412 ◽  
Author(s):  
N. H. HUNT ◽  
T. J. MARTIN ◽  
V. P. MICHELANGELI ◽  
J. A. EISMAN
Keyword(s):  
Parathyroid Hormone ◽  
Adenylate Cyclase ◽  
Plasma Membranes ◽  
Enzyme Activation ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Amino Terminal ◽  
Nucleotide Analogue ◽  
Amino Terminal Fragment ◽  
Chick Kidney

SUMMARY Both guanosine 5′-triphosphate (GTP) and 5′-guanylylimidodiphosphate (Gpp(NH)p) activated adenylate cyclase (EC 4.6.1.1) in chick kidney plasma membranes. Half-maximal stimulation occurred at 3·1 × 10−6 m for both agents. The maximum increases in adenylate cyclase activity produced by GTP and Gpp(NH)p were respectively 130 and 720% over basal activity. At the end of a 12 min incubation period GTP concentration was 85% of that originally added in the presence of an ATP-regenerating system but less than 20% in its absence. GTP and guanosine 5′-diphosphate inhibited the activation of adenylate cyclase by Gpp(NH)p, suggesting that they all acted at a common site. Gpp(NH)p facilitated the stimulation of adenylate cyclase activity by bovine parathyroid hormone (BPTH) and by the synthetic amino terminal fragment BPTH (1–34), decreasing the concentrations required for half-maximal enzyme activation by a factor of approximately eight in both cases. This property was not shared by the native nucleotide GTP. Gpp(NH)p rendered active (at certain concentrations) a synthetic parathyroid hormone peptide fragment, BPTH (2–34), which was incapable of activating adenylate cyclase in the absence of the nucleotide analogue. This suggested that the GTP analogue, in addition to a direct effect upon adenylate cyclase activity, was capable of influencing hormone interaction with the enzyme complex.

Arrhenius plot characteristics of adipocyte-plasma-membrane adenylate cyclase activity in lean and genetically obese (ob/ob) mice

1984 ◽  
Vol 4 (12) ◽  
pp. 1001-1008
Author(s):  
R. R. French ◽  
D. A. York
Keyword(s):  
Adenylate Cyclase ◽  
Plasma Membranes ◽  
Arrhenius Plot ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Obese Mice ◽  
Arrhenius Plots ◽  
Β Receptor ◽  
Lipid Environment ◽  
Adipocyte Plasma Membranes

Arrhenius plots of fluoride- and guanine-nucleotide-stimulated adenylate cyclase activity were linear in adipocyte plasma membranes from lean and obese (ob/ob) mice. Arrhenius plots of isoprenaline-stimulated adenylate cyclase activity in hepatic plasma membranes biphasic in both groups. The results were biphasic in membranes from Jean mice but linear in membranes from obese mice. In contrast, Arrhenius plots of glucagon-stimulated adenylate cyclase activity in hepatic plasma membranes were biphasic in both groups. The results suggest that the coupling between the β-receptor and the regulatory unit of adenylate cyclase, which has been observed to be defective in adipocyte plasma membranes from obese mice, is influenced by a different lipid environment in membranes from obese animals.

Adenylate cyclase activity in Y1 mouse adrenocortical tumor cells: some properties of the enzyme associated with purified plasma membrane fractions

1983 ◽  
Vol 61 (7) ◽  
pp. 547-552 ◽  
Author(s):  
Bernard P. Schimmer
Keyword(s):  
Plasma Membrane ◽  
Adenylate Cyclase ◽  
Plasma Membranes ◽  
Tumor Cell Line ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Adenylate Cyclase System ◽  
Adrenocortical Tumor ◽  
Intact Cells ◽  
Order Of Magnitude

Fractions enriched in plasma membranes were prepared from the Y1 mouse adrenocortical tumor cell line and were characterized with respect to adenylate cyclase activity. Optimal requirements of the adenylate cyclase system for guanyl nucleotides, Mg2+, ATP, and corticotropin (ACTH) were determined. The sensitivity of the adenylate cyclase system to ACTH1–24 in plasma membrane fractions was comparable with that observed in isolated intact cells. Polycations such as poly-L-arginine and histone competitively inhibited the action of ACTH1–24, supporting the view that the affinity of ACTH for the adenylate cyclase system is determined by the basic core of amino acids at residues 15–18. ACTH1–24 was at least one order of magnitude more potent than ACTH1–39 in stimulating adenylate cyclase activity in plasma membrane fractions.

Sign in / Sign up

Export Citation Format

Share Document