scholarly journals Regulation of basal adenylate cyclase activity in neuroblastoma × glioma hybrid, NG108-15, cells transfected to express the human β 2 adrenoceptor: evidence for empty receptor stimulation of the adenylate cyclase cascade

1994 ◽  
Vol 303 (3) ◽  
pp. 803-808 ◽  
Author(s):  
E J Adie ◽  
G Milligan
Keyword(s):  
Membrane Protein ◽  
Adenylate Cyclase ◽  
Receptor Activation ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Wild Type ◽  
Catalytic Unit ◽  
Beta 2 ◽  
Signalling Cascade ◽  
Stimulation Of

Clones of neuroblastoma x glioma hybrid, NH108-15, cells expressing differing levels of the human beta 2 adrenoceptor were isolated. Two clones were examined in detail, beta N22 which expressed some 4000 fmol/mg of membrane protein and clone beta N17 which expressed approx. 300 fmol/mg of membrane protein of the receptor. In beta N22 cells ‘basal’ adenylate cyclase activity measured in the presence of Mg2+ was significantly greater than that in wild-type NG108-15 or beta N17 cells. Both isoprenaline and iloprost were able to stimulate adenylate cyclase activity in each of beta N22 and beta N17 membranes. However, the EC50 for isoprenaline stimulation of adenylate cyclase in membranes of beta N22 cells (6 nM) was significantly lower than that in membranes of beta N17 cells (80 nM), whereas the EC50 for iloprost stimulation of adenylate cyclase (approx. 25 nM) was the same in the two clones and in parental NG108-15 cells. The high basal adenylate cyclase activity of beta N22 cell membranes was not a reflection of higher levels of expression of the adenylate cyclase catalytic unit, as adenylate cyclase activity measured in the presence of Mn2+ was equivalent in membranes of each of wild-type NG108-15 cells and clones beta N22 and beta N17. Basal adenylate cyclase activity measured in the presence of Mg2+ in clone beta N22 was significantly reduced, however, by the beta-receptor antagonist propranolol, whereas this agent was without effect on basal adenylate cyclase activity in membranes of wild-type NG108-15 cells. These data indicate that the elevated basal adenylate cyclase cascade in NG108-15 cells expressing high levels of the beta 2 adrenoceptor represents empty receptor activation of the signalling cascade.

Stimulation of Thyroid Adenylate Cyclase Activity in Sera of Patients with Nonthyroidal Illness

1986 ◽  
pp. 385-389
Author(s):  
F. Kakezono ◽  
S. Yamashita ◽  
N. Yokoyama ◽  
S. Morita ◽  
S. Okamoto ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Nonthyroidal Illness ◽  
Stimulation Of

Prostaglandin E2-binding sites and cAMP production in porcine fundic mucosa

1981 ◽  
Vol 241 (4) ◽  
pp. G313-G320
Author(s):  
B. L. Tepperman ◽  
B. D. Soper
Keyword(s):  
Adenylate Cyclase ◽  
Prostaglandin E2 ◽  
Binding Site ◽  
Binding Sites ◽  
Biologically Active ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Scatchard Analysis ◽  
Fundic Mucosa ◽  
Stimulation Of

Biologically active [3H]prostaglandin E2 (PGE2) bound rapidly and specifically to membrane fractions from hog fundic mucosa. Optimal binding occurred in the 30,000-g membrane preparation at 37 degrees C (pH 5.0). Scatchard analysis of specific PgE2 binding revealed the presence of a heterogeneous population of binding sites with Kd values and binding site concentrations of approximately 1 X 10(-9) M and 1 fmol/mg prot and 2 X 10(-8) M and 20 fmol/mg prot, respectively. Specific binding was inhibited by the following agents in descending order of potency: PGE1, PGA2, PGD2, 6-keto-PGF1 alpha, and thromboxane B2. Trypsin treatment or boiling reduced or abolished specific PGE2 binding. PGE2 stimulated cAMP formation in the 2,500-g fraction, with an approximate Km of 1 X 10(-6) M, but stimulation of adenylate cyclase activity by PG was not evident in the 16,000-g or 30,000-g tissue preparations. These results suggest that a specific PGE2-binding site exists in the 16,000-g and 30,000-g fractions of porcine fundic mucosa, although an increase in cAMP-forming capacity could not b of 1 X 10(-6) M, but stimulation of adenylate cyclase activity by PG was not evident in the 16,000-g or 30,000-g tissue preparations. These results suggest that a specific PGE2-binding site exists in the 16,000-g and 30,000-g fractions of porcine fundic mucosa, although an increase in cAMP-forming capacity could not b of 1 X 10(-6) M, but stimulation of adenylate cyclase activity by PG was not evident in the 16,000-g or 30,000-g tissue preparations. These results suggest that a specific PGE2-binding site exists in the 16,000-g and 30,000-g fractions of porcine fundic mucosa, although an increase in cAMP-forming capacity could not be localized in these fractions in vitro.

Effect of histamine on canine gastric mucosal adenylate cyclase.

1977 ◽  
Vol 232 (1) ◽  
pp. E35
Author(s):  
R R Dozois ◽  
A Wollin ◽  
R D Rettmann ◽  
T P Dousa
Keyword(s):  
Gastric Mucosa ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Antral Mucosa ◽  
Fundic Mucosa ◽  
H2 Receptors ◽  
Dose Dependent ◽  
Stimulation Of

The effects of histamine, Nalpha-dimethylhistamine, 4,5-methylhistamine, Ntau-methylhistamine, pentagastrin, carbachol, and NaF on the adenylate cyclase activity from canine gastric mucosa were investigated in cell-free preparations. In gastric fundic mucosa, histamine (10(-4) M), Nalpha-dimethylhistamine (10(-4) M), 4,5-methylhistamine (10(-4 M), and NaF (10)-2) M) significantly (P less than 0.001) increased adenylate cyclase activity (means+/-SE) by 44.7+/-6.6, 49.4+/-6.7, 34.0+/-6.4, and 572.0+/-100%, respectively, above basal activity. The effect of histamine and Na-dimethyl histamine was dose-dependent. In contrast, other tested agents failed to stimulate the formation of cyclic AMP in gastric fundic mucosa. Metiamide (10(-4) M) blocked the stimulation of fundic mucosa adenylate cyclase by histamine and Nalpha-dimethylhistamine, without significantly altering basal and NaF-induced adenylate cyclase activity. Histamine, however, did not stimulate the adenylate cyclase activity from the gastric antral mucosa. The findings support the proposal that the canine gastric acid response to histamine may be mediated by cyclic AMP formed in response to stimulation of histamine H2-receptors.

scholarly journals Catecholamine-sensitive adenylate cyclase of caudate nucleus and cerebral cortex. Effects of guanine nucleotides

1977 ◽  
Vol 164 (1) ◽  
pp. 67-74 ◽  
Author(s):  
P V Sulakhe ◽  
N L Leung ◽  
A T Arbus ◽  
S J Sulakhe ◽  
S H Jan ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Cerebral Cortex ◽  
Adenylate Cyclase ◽  
Caudate Nucleus ◽  
Protein S ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Biphasic Effect ◽  
Site Binding ◽  
Stimulation Of

1. GTP and GMP-P(NH)P (guanyl-5'-yl imidodiphosphate) were observed to increase the stimulation of neural adenylate cyclase by dopamine (3,4-dihydroxyphenethylamine) and noradrenaline. 2. GMP-P(NH)P had a biphasic effect on the enzyme activity. 3. Preincubation of membranes with GMP-P(NH)P activated the enzyme by a process dependent on time and temperature. Catecholamines increased the speed and the extent of this activation. 4. Membrane fractions contained high- and low-affinity sites for GMP-P(NH)P binding: this binding was due to protein(s) of the membrane preparations. 5. Low-affinity-site binding of GMP-P(NH)P appeared to be related to the stimulatory effect on the adenylate cyclase activity.

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