scholarly journals Elucidation of the quaternary structure of the insulin receptor

1983 ◽  
Vol 212 (1) ◽  
pp. 79-84 ◽  
Author(s):  
M D Baron ◽  
P H Sönksen
Keyword(s):  
Insulin Receptor ◽  
Rat Liver ◽  
Plasma Membranes ◽  
Quaternary Structure ◽  
Insulin Binding ◽  
Insulin Analogues ◽  
Cross Link ◽  
Disuccinimidyl Suberate ◽  
Rat Liver Plasma Membranes ◽  
Binding Subunit

Photoreactive insulin analogues specifically label predominantly one polypeptide in the insulin receptor of rat liver plasma membranes. We have used the bifunctional reagent disuccinimidyl suberate to cross-link this polypeptide to its neighbouring, but not necessarily labelled, subunits. The results of these studies show that (1) there are at least three types of subunit in the receptor, with apparent Mr (Mapp.) values of 65 000, 95 000 and 120 000; (2) the receptor appears to consist of two Mapp. 120 000, one Mapp. 95 000 and one Mapp. 65 000 subunits; (3) the Mapp. 65 000 subunit, which has not been previously reported, may be only loosely attached to the receptor, and does not interact directly with the insulin-binding subunit (M app. 120 000).

Characterization of two insulin-binding components of rat-liver plasma membranes

1982 ◽  
Vol 2 (10) ◽  
pp. 785-793 ◽  
Author(s):  
M. D. Baron ◽  
P. H. Sónksen
Keyword(s):  
Rat Liver ◽  
Plasma Membranes ◽  
Insulin Binding ◽  
Affinity Binding ◽  
Dissociation Kinetics ◽  
High Affinity ◽  
Liver Plasma Membranes ◽  
Rat Liver Plasma Membranes ◽  
Single Polypeptide

We have identified and isolated two forms of insulin receptor from rat-liver plasma membranes. The smaller (Mr = 90k) is a single polypeptide. The same poly-peptide appears to be the insulin-binding site of the largerMr = 280k). Only the larger, multisubunit, receptor shows high-affinity binding of insulin and negative cooperativity in its dissociation kinetics.

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 The roles of phospholipase D and a GTP-binding protein in guanosine 5′-[γ-thio]triphosphate-stimulated hydrolysis of phosphatidylcholine in rat liver plasma membranes

1990 ◽  
Vol 272 (3) ◽  
pp. 749-753 ◽  
Author(s):  
K M Hurst ◽  
B P Hughes ◽  
G J Barritt
Keyword(s):  
Rat Liver ◽  
Phospholipase D ◽  
Plasma Membranes ◽  
Regulatory Protein ◽  
Gtp Binding ◽  
Liver Plasma Membranes ◽  
Low Concentrations ◽  
Rat Liver Plasma Membranes ◽  
Triton X ◽  
Hydrolysis Of

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.

Receptors for calcitonin gene-related peptide on the rat liver plasma membranes

1988 ◽  
Vol 152 (1) ◽  
pp. 383-391 ◽  
Author(s):  
Akinori Yamaguchi ◽  
Tsutomu Chiba ◽  
Yasuhiko Okimura ◽  
Toshiyuki Yamatani ◽  
Tomoyuki Morishita ◽  
...  
Keyword(s):  
Rat Liver ◽  
Plasma Membranes ◽  
Calcitonin Gene Related Peptide ◽  
Related Peptide ◽  
Liver Plasma Membranes ◽  
Calcitonin Gene ◽  
Rat Liver Plasma Membranes
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