Calmodulin selectively modulates the guanylate cyclase activity by repressing the lipid phase separation temperature in the inner half of the bilayer of rat brain synaptosomal plasma membranes

1989 ◽  
Vol 14 (2) ◽  
pp. 119-127 ◽  
Author(s):  
Kopeikina-Tsiboukidou Lioudmila ◽  
George Deliconstantinos
Keyword(s):  
Phase Separation ◽  
Rat Brain ◽  
Guanylate Cyclase ◽  
Plasma Membranes ◽  
Lipid Phase ◽  
Phase Separation Temperature ◽  
Guanylate Cyclase Activity ◽  
Separation Temperature ◽  
Lipid Phase Separation ◽  
Synaptosomal Plasma Membranes

scholarly journals Acidic phospholipid species inhibit adenylate cyclase activity in rat liver plasma membranes

1986 ◽  
Vol 235 (1) ◽  
pp. 237-243 ◽  
Author(s):  
M D Houslay ◽  
L Needham ◽  
N J Dodd ◽  
A M Grey
Keyword(s):  
Phase Separation ◽  
Adenylate Cyclase ◽  
Plasma Membranes ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Lipid Phase ◽  
Liver Plasma Membranes ◽  
Native Liver ◽  
Rat Liver Plasma Membranes ◽  
Lipid Phase Separation

Incubation of rat liver plasma membranes with liposomes of dioleoyl phosphatidic acid (dioleoyl-PA) led to an inhibition of adenylate cyclase activity which was more pronounced when fluoride-stimulated activity was followed than when glucagon-stimulated activity was followed. If Mn2+ (5 mM) replaced low (5 mM) [Mg2+] in adenylate cyclase assays, or if high (20 mM) [Mg2+] were employed, then the perceived inhibitory effect of phosphatidic acid was markedly reduced when the fluoride-stimulated activity was followed but was enhanced for the glucagon-stimulated activity. The inhibition of adenylate cyclase activity observed correlated with the association of dioleoyl-PA with the plasma membranes. Adenylate cyclase activity in dioleoyl-PA-treated membranes, however, responded differently to changes in [Mg2+] than did the enzyme in native liver plasma membranes. Benzyl alcohol, which increases membrane fluidity, had similar stimulatory effects on the fluoride- and glucagon-stimulated adenylate cyclase activities in both native and dioleoyl-PA-treated membranes. Incubation of the plasma membranes with phosphatidylserine also led to similar inhibitory effects on adenylate cyclase and responses to Mg2+. Arrhenius plots of both glucagon- and fluoride-stimulated adenylate cyclase activity were different in dioleoyl-PA-treated plasma membranes, compared with native membranes, with a new ‘break’ occurring at around 16 degrees C, indicating that dioleoyl-PA had become incorporated into the bilayer. E.s.r. analysis of dioleoyl-PA-treated plasma membranes with a nitroxide-labelled fatty acid spin probe identified a new lipid phase separation occurring at around 16 degrees C with also a lipid phase separation occurring at around 28 degrees C as in native liver plasma membranes. It is suggested that acidic phospholipids inhibit adenylate cyclase by virtue of a direct headgroup specific interaction and that this perturbation may be centred at the level of regulation of this enzyme by the stimulatory guanine nucleotide regulatory protein NS.

scholarly journals Glucagon-stimulated adenylate cyclase detects a selective perturbation of the inner half of the liver plasma-membrane bilayer achieved by the local anaesthetic prilocaine

1980 ◽  
Vol 190 (1) ◽  
pp. 131-137 ◽  
Author(s):  
M D Houslay ◽  
I Dipple ◽  
S Rawal ◽  
R D Sauerheber ◽  
J A Esgate ◽  
...  
Keyword(s):  
Phase Separation ◽  
Fatty Acid ◽  
Adenylate Cyclase ◽  
Rat Liver ◽  
Spin Probe ◽  
Plasma Membranes ◽  
Lipid Phase ◽  
Rat Liver Plasma Membranes ◽  
Membrane Bound ◽  
Lipid Phase Separation

Prilocaine can increase the fluidity of rat liver plasma membranes, as indicated by a fatty acid spin-probe. This led to the activation of the membrane-bound fluoride-stimulated adenylate cyclase activity, but not the Lubrol-solubilized activity, suggesting that increased lipid fluidity can activate the enzyme. With increasing prilocaine concentrations above 10 mM, the membrane-bound fluoride-stimulated activity was progressively inhibited, even though bilayer fluidity continued to increase and the activity of the solubilized enzyme remained unaffected. Glucagon-stimulated adenylate cyclase was progressively inhibited by increasing prilocaine concentrations. Prilocaine (10 mM) had no effect on the lipid phase separation occurring at 28 degrees C and attributed to those lipids in the external half of the bilayer, as indicated by Arrhenius plots of both glucagon-stimulated adenylate cyclase activity and the order parameter of a fatty acid spin-probe. However, 10 mM-prilocaine induced a lipid phase separation at around 11 degrees C that was attributed to the lipids of the internal (cytosol-facing) half of the bilayer. It is suggested that prilocaine (10 mM) can selectively perturb the inner half of the bilayer of rat liver plasma membranes owing to its preferential interaction with the acidic phospholipids residing there.

scholarly journals Influence of Salt on the Self-Organization in Solutions of Star-Shaped Poly-2-alkyl-2-oxazoline and Poly-2-alkyl-2-oxazine on Heating

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1152
Author(s):  
Tatyana Kirila ◽  
Anna Smirnova ◽  
Alla Razina ◽  
Andrey Tenkovtsev ◽  
Alexander Filippov
Keyword(s):  
Phase Separation ◽  
Salt Concentration ◽  
Monomer Unit ◽  
Salt Content ◽  
The Self ◽  
Self Organization ◽  
Phase Separation Temperature ◽  
The Core ◽  
Separation Temperature ◽  
Water Salt

The water–salt solutions of star-shaped six-arm poly-2-alkyl-2-oxazines and poly-2-alkyl-2-oxazolines were studied by light scattering and turbidimetry. The core was hexaaza[26]orthoparacyclophane and the arms were poly-2-ethyl-2-oxazine, poly-2-isopropyl-2-oxazine, poly-2-ethyl-2-oxazoline, and poly-2-isopropyl-2-oxazoline. NaCl and N-methylpyridinium p-toluenesulfonate were used as salts. Their concentration varied from 0–0.154 M. On heating, a phase transition was observed in all studied solutions. It was found that the effect of salt on the thermosensitivity of the investigated stars depends on the structure of the salt and polymer and on the salt content in the solution. The phase separation temperature decreased with an increase in the hydrophobicity of the polymers, which is caused by both a growth of the side radical size and an elongation of the monomer unit. For NaCl solutions, the phase separation temperature monotonically decreased with growth of salt concentration. In solutions with methylpyridinium p-toluenesulfonate, the dependence of the phase separation temperature on the salt concentration was non-monotonic with minimum at salt concentration corresponding to one salt molecule per one arm of a polymer star. Poly-2-alkyl-2-oxazine and poly-2-alkyl-2-oxazoline stars with a hexaaza[26]orthoparacyclophane core are more sensitive to the presence of salt in solution than the similar stars with a calix[n]arene branching center.

ACTH SOLUBILIZATION OF A KINASE FROM RAT BRAIN SYNAPTOSOMAL PLASMA MEMBRANES

1981 ◽  
Vol 9 (2) ◽  
pp. 356P-356P
Author(s):  
V. J. Aloyo ◽  
H. Zwiers ◽  
P. R. Bär ◽  
W. H. Gispen
Keyword(s):  
Rat Brain ◽  
Plasma Membranes ◽  
Synaptosomal Plasma Membranes

Time-dependent cadmium-neurotoxicity in rat brain synaptosomal plasma membranes

1991 ◽  
Vol 100 (1-2) ◽  
pp. 271-275 ◽  
Author(s):  
C.D. Fasitsas ◽  
S.E. Theocharis ◽  
D. Zoulas ◽  
S. Chrissimou ◽  
G. Deliconstantinos
Keyword(s):  
Rat Brain ◽  
Plasma Membranes ◽  
Time Dependent ◽  
Synaptosomal Plasma Membranes

scholarly journals Phenobarbital selectively modulates the glucagon-stimulated activity of adenylate cyclase by depressing the lipid phase separation occurring in the outer half of the bilayer of liver plasma membranes

1981 ◽  
Vol 197 (3) ◽  
pp. 675-681 ◽  
Author(s):  
M D Houslay ◽  
I Dipple ◽  
L M Gordon
Keyword(s):  
Adenylate Cyclase ◽  
Spin Probe ◽  
Plasma Membranes ◽  
Chemical Constituents ◽  
Lipid Phase ◽  
Lipid Phase Transition ◽  
Arrhenius Plots ◽  
Lipid Environment ◽  
Lipid Phase Separation ◽  
Outer Half

The glucagon-stimulated (coupled) activity of rat liver plasma-membrane adenylate cyclase could be selectively modulated by the anionic drug phenobarbital, whereas the fluoride-stimulated (uncoupled) activity remained unaffected. It is suggested that the cationic drug phenobarbital preferentially interacts with the external half of the bilayer, as the negatively charged phospholipids are found at the cytosol-facing side. This results in a selective fluidization of the external half of the bilayer, leading to a depression in the high-temperature onset of the lipid phase transition (from 28 degree to 16 degree C) occurring there. This was detected both by e.s.r. analysis, using a fatty acid spin probe, and also by Arrhenius plots of glucagon-stimulated activity, where the enzyme forms a transmembrane complex with the receptor and is sensitive to the lipid environment of both halves of the bilayer. However, in the absence of hormone, adenylate cyclase only senses the lipid environment of the inner (cytosol) half of the bilayer. Thus its fluoride stimulated activity and Arrhenius plots of this activity remained unaffected by the presence of phenobarbital (less than 12 mM) in the assay. These results support the view that independent modulation of the fluidity or chemical constituents of each half of the bilayer can selectively affect the receptor-coupled and uncoupled activities of adenylate cyclase.

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