Glucagon from avian pancreatic islets: radioreceptor studies

1977 ◽  
Vol 55 (8) ◽  
pp. 915-918 ◽  
Author(s):  
Anthony K. Tung ◽  
Steven A. Rosenzweig ◽  
Piero P. Foa

Glucagon extracted from isolated islets of the pigeon was studied by means of Sephadex gel filtration. Radioreceptor assay, using rat liver plasma membranes and radioiodinated porcine glucagon, showed that the bulk of the activity eluted with glucagon (molecular weight 3500). Avian glucagon appeared to be less effective than porcine glucagon in inhibiting the binding of labeled porcine glucagon to rat plasma membranes.

1986 ◽  
Vol 6 (1) ◽  
pp. 39-44 ◽  
Author(s):  
J. M. Guerrero ◽  
J. R. Calvo ◽  
M. R. Garrido ◽  
P. Molinero ◽  
C. Osuna ◽  
...  

A non-ionic detergent such as Lubrol-PX extracts in soluble form the VIP-binding structures of rat liver plasma membranes. Detergent-solubitized proteins bind specifically [125I]VIP and the complex tracer-protein is identified by the use of Sepharose 6B columns. The interaction is only possible in the absence of detergent (below 0.001%) and is inhibited by native peptide. A molecular weight of about 80,000 was estimated for VIP-binding proteins by reference to a series of globular markers of proteins. Binding to VIP soluble proteins is specific and dependent on time as studied by the Hummel and Dreyer (Biochim. Biophys. Acta63:530–532, 1962) assay.


1979 ◽  
Vol 178 (1) ◽  
pp. 217-221 ◽  
Author(s):  
M D Houslay ◽  
R W Palmer

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.


1990 ◽  
Vol 272 (3) ◽  
pp. 749-753 ◽  
Author(s):  
K M Hurst ◽  
B P Hughes ◽  
G J Barritt

1. Guanosine 5′-[gamma-thio]triphosphate (GTP[S]) stimulated by 50% the rate of release of [3H]choline and [3H]phosphorylcholine in rat liver plasma membranes labelled with [3H]choline. About 70% of the radioactivity released in the presence of GTP[S] was [3H]choline and 30% was [3H]phosphorylcholine. 2. The hydrolysis of phosphorylcholine to choline and the conversion of choline to phosphorylcholine did not contribute to the formation of [3H]choline and [3H]phosphorylcholine respectively. 3. The release of [3H]choline from membranes was inhibited by low concentrations of SDS or Triton X-100. Considerably higher concentrations of the detergents were required to inhibit the release of [3H]phosphorylcholine. 4. Guanosine 5′-[beta gamma-imido]triphosphate and guanosine 5′-[alpha beta-methylene]triphosphate, but not adenosine 5′-[gamma-thio]-triphosphate, stimulated [3H]choline release to the same extent as did GTP[S]. The GTP[S]-stimulated [3H]choline release was inhibited by guanosine 5′-[beta-thio]diphosphate, GDP and GTP but not by GMP. 5. It is concluded that, in rat liver plasma membranes, (a) GTP[S]-stimulated hydrolysis of phosphatidylcholine is catalysed predominantly by phospholipase D with some contribution from phospholipase C, and (b) the stimulation of phosphatidylcholine hydrolysis by GTP[s] occurs via a GTP-binding regulatory protein.


1988 ◽  
Vol 152 (1) ◽  
pp. 383-391 ◽  
Author(s):  
Akinori Yamaguchi ◽  
Tsutomu Chiba ◽  
Yasuhiko Okimura ◽  
Toshiyuki Yamatani ◽  
Tomoyuki Morishita ◽  
...  

PROTOPLASMA ◽  
1995 ◽  
Vol 184 (1-4) ◽  
pp. 111-117 ◽  
Author(s):  
C. Kim ◽  
F. L. Crane ◽  
G. W. Becker ◽  
D. J. Morr�

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