Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The changes in glucagon receptors of white adipocytes from cold-acclimated rats were investigated to know the metabolic role of glucagon in cold acclimation by establishing a glucagon radioreceptor assay system for isolated white adipocytes. Glucagon radioreceptor assay methodology The binding of 125I-labelled glucagon to isolated epididymal white adipocytes was linearly related to the number of cells (0.5-2.0 X 10(5) cells/ml) added in the medium. At a cell concentration higher than 3.0 X 10(5) cells/ml, the amount of specific binding failed to show the proportional relationship to the number of adipocytes. The effects of incubation temperature (4 degrees C, 25 degrees C and 37 degrees C) on the glucagon binding were investigated. Incubation at 25 degrees C was adopted in the present study because of the highest maximum binding and the longest steady state obtained. Preincubation at 25 degrees C for 15 min increased significantly the amount of specific binding. It was confirmed that bacitracin, polypeptide antibiotics, inhibited significantly the degradation of glucagon. The glucagon binding under these conditions was found to be saturable and reversible, validating a specific reaction for the glucagon receptor. When a Scatchard plot was constructed, the data was curvilinear with an upward concavity, indicating the presence of at least two classes of binding site with different fixed affinities or of negatively cooperative interactions between receptors. It was concluded that an appropriate condition for glucagon receptor assay of white adipocytes consists of cell concentration of 1 X 10(5) cells/ml, 15 minute-preincubation and 30 minute-reaction at 25 degrees C in the presence of bacitracin (1 mg/ml). Effect of cold acclimation on glucagon receptors of white adipocytes Cold acclimation decreased the size and increased the number of epididymal white adipocytes. Cold acclimation increased the number of glucagon receptors of white adipocytes; about 140% increase expressed as per cell, approximately 260% increase per unit of surface area and 210% increase per whole tissue. The affinity of binding sites was not changed. The increased binding sites could explain, at least partly, the enhanced metabolic response of cold-acclimated rats to glucagon.
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PMID:[Studies on adipocyte glucagon receptor assay--with special reference to the effect of cold acclimation on glucagon receptors of white adipocytes]. 299 Oct 98

In order to determine the role of glucagon in cold acclimation, the changes in glucagon receptor were investigated in white adipocytes from cold-acclimated rats by establishing a glucagon radioreceptor assay method for isolated white adipocytes. The following conditions were found to be appropriate for specific glucagon receptor binding assay; cell concentration of about 1 X 10(5) cells/ml, 15 min preincubation with glucagon and 30 min-reaction at 25 degrees C in the presence of bacitracin (1 mg/ml). Cold acclimation decreased the size and increased the number of epididymal white adipocytes. Cold acclimation increased the number of glucagon receptors of white adipocytes, resulting in 140% in terms of unit cell, and 260% increase per unit surface area and 210% increase per whole tissue. However, the affinity of the binding site for glucagon was not affected. The results suggested that an enhanced metabolic response of cold-acclimated rats to glucagon could be partly explained by the increased number of glucagon receptor in white adipocytes.
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PMID:Effect of cold acclimation on glucagon receptors of rat white adipocytes. 303 47

A series of glucagon analogues, des-(1-4)-glucagon, des-(5-9)-glucagon, des-(10-15)-glucagon, des-(16-21)-glucagon, des-(22-26)-glucagon and des-(27-29)-glucagon, were prepared by condensation of synthetic fragments and characterized biologically and immunologically. Fully synthetic glucagon was also characterized. The potencies with regard to glucagon receptor binding in purified rat liver plasma membranes were, in decreasing order: synthetic glucagon 108%, des-(1-4)-glucagon 5.7%, des-(27-29)-glucagon 0.92%, des-(5-9)-glucagon 0.47%, des-(10-15)-glucagon 0.0028%, des-(16-21)-glucagon 0.0017% and des-(22-26)-glucagon 0.00060% relative to that of natural porcine glucagon. Des-(27-29)-glucagon was the only analogue that activated the adenylate cyclase in rat liver plasma membranes or stimulated the lipolysis in isolated free fat cells from rat epididymal fat pad. The potencies were 0.16% and 0.20% of that of glucagon, respectively. Des-(1-4)-glucagon was a glucagon antagonist in the adenylate cyclase assay. The immunoreactivities of the glucagon analogues were determined with two commonly used anti-glucagon sera, K 5563 and K 4023, directed towards the C-terminus and some segment in the sequence 2-23, respectively. In the K 5563 assay, des-(27-29)-glucagon and des-(22-26)-glucagon had potencies of 0.0009% and less than 0.09% of that of glucagon, respectively. The remaining analogues had potencies varying from 45% to 141% of that of glucagon. In the K 4023 assay, the analogues showed a non-linear dilution effect. The combined results indicate a partition within the glucagon molecule with regard to receptor binding and adenylate cyclase activation. The region 10-26 appears to be the most important for receptor binding, whereas 1-4 is essential for adenylate cyclase activation. The C-terminal segment 27-29 is important for the maintenance of full receptor binding but non-essential for adenylate cyclase activation.
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PMID:Glucagon: structure-function relationships investigated by sequence deletions. 626 19