Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01275 (glucagon)
 26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A membrane fraction enriched in parathyroid hormone (PTH)-sensitive adenylate cyclase and sodium and potassium ion-activated (Na+, K+)-ATPase was prepared from bovine kidney. Tritiated PTH binding to this membrane fraction was dependent on both hormone and membrane protein concentration. Both total and specific binding of the hormone decreased significantly after 5 to 10 min of incubation at 22 degrees. PTH binding was highly specific, being sensitive to inhibition only with active forms of unlabeled hormone (native and 1-34 PTH). Specific binding showed a pH optimum of 7.3 to 7.5. Inhibition of binding of tritiated hormone by unlabeled PTH was also highly effective at pH 6.0, but this apparently specific binding was also inhibited by adrenocorticotropic hormone, insulin, glucagon, and vasopressin. Dissociation of bound hormone was demonstrated, and an apparent dissociation constant of 4.6 X 10(-2) min-1 was obtained. Specific binding was eliminated by pretreatment of the membranes with trypsin. The concentration dependence for inhibition of binding with unlabeled PTH was identical to that for activation of adenylate cyclase in this membrane preparation, and binding was also inhibited by concentrations of calcium in the 0.5 to 2 mM range.
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PMID:Binding of tritiated bovine parathyroid hormone to plasma membranes from bovine kidney cortex. 1 29

A 53 year old woman presented with diabetes mellitus, hyperglucagonemia (600 to 1,500 pg/ml), clinical hyperparathyroidism and an abdominal mass diagnosed on biopsy as an islet cell carcinoma. Glucagon content of the tumor was 0.78 mug/g wet weight. Hourly blood samples during a 24 hour period revealed a direct correlation between plasma glucose and glucagon. The oral administration of glucose paradoxically increased whereas the intravenous administration decreased plasma glucagon. Circulating glucagon levels were markedly increased with arginine and epinephrine infusion. Both short- and long-term administration of alpha adrenergic blockade depressed the glucagon response to epinephrine infusion. In contrast, long-term alpha adrenergic blockade increased glucagon secretion despite improved glucose tolerance during a second 24 hour study. Although the patient demonstrated overt clinical and chemical findings of hyperparathyroidism, parathyroid hormone (PTH) was not detected in her plasma. The pattern of tumor growth was consistent with an origin from pancreatic islets. We conclude that (1) the tumor was responsive to physiologic stimuli known to affect glucagon secretion; (2) elevations of plasma glucagon levels with oral and dietary glucose suggest regulation of secretion by intestinal factors; and (3) improvement of glucose tolerance with alpha adrenergic blockade may be related to increased insulin secretion.
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PMID:Uncontrolled diabetes mellitus and hyperglucagonemia associated with an islet cell carcinoma. 4 4

Chronic renal failure results in a variety of metabolic derangements that perturb glucose homeostasis. These may in part result from the fact that the kidney plays a prominent role in the metabolism of insulin as well as a number of other low-molecular-weight peptide hormones that affect carbohydrate metabolism. Specific abnormalities in glucose utilization that appear to be related to alterations in membrane receptors, resulting in increased glucagon sensitivity and decreased insulin action, are a newly recognized factor in intolerance to oral glucose. Glucose production and utilization are both abnormally increased in patients with chronic uremia, and these disturbances are only partially corrected by hemodialysis treatment. The mechanism(s) contributing to these changes is unclear, but seems to involve a combination of humoral and cellular factors. These include some degree of insulin resistance, probably inadequately modulated proteolytic responses to glucagon and parathyroid hormone, and a basic defect in energy production that alters intracellular concentrations of high-energy phosphate-containing nucleotides. It is unclear whether these changes in carbohydrate tolerance pose an increased risk for the premature development of cardiovascular disease in patients with renal failure, as they appear to do in the nonuremic population. The occasional patient with renal failure may develop clinical hypoglycemia when glucose utilization continues in a setting in which the hepatic capacity to produce glucose is reduced, probably as a consequence of altered substrate delivery and/or inhibition of one or more key gluconeogenic enzymes.
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PMID:Disorders of glucose metabolism in uremia. 11 52

The hormonal responsiveness of plasma membrane-bound enzymes (Na-+-K-+)-ATPase and adenylate cyclase has been investigated in normal and regenerating rat liver. (Na-+-K-+)-ATPase basal activity is not affected by surgery and only slightly affected by partial hepatectomy; its response to epinephrine and cyclic AMP is decreased only 15 h after hepatectomy. Adenylate cyclase activity of plasma membranes from untreated animals is stimulated by parathyroid hormone and thyroxine; partial hepatectomy increased basal activity as well as the stimulation exerted by the aforementioned hormones, when glucagon and epinephrine sensitivity is essentially unaltered.
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PMID:Hormone responsiveness of plasma membrane-bound enzymes in normal and regenerating rat liver. 12 2

Differences exist in the rates at which hormones are inactivated by, or dissociate from, their target tissues. The present studies examined the binding of biologically active TSH to thyroid slices and compared its characteristics to those of PGE. Canine thyroid slices were initally incubated with 5 mU/ML OF BOVINE TSH (TSH-Inital) for 15 min, washed and incubated in media free of hormone for 3 hr. At the conclusion of this second incubation period all slices were again washed. Some were then transferred to media containing 10-2M theophylline for a final 10 min incubation and subsequent measurement of cAMP and protein kinase, while others were transferred to media containing (l-14C)glucose without theophylline for a final 45 min incubation to assess glucose oxidation. Identically treated slices never exposed to TSH served as controls, while others were exposed to TSH only during the final 10 or 45 min incubation periods (TSH-Final). cAMP content determined after significantly increased in TSH-Initial (mean 2.98 plus or minus 0.36 (se) pmol/mg wet wt) compared to control (0.35 plus or minus 0.04), but was less than that in TSH-Final (5.76 plus or minus 0.51). This phenomenon was not unique to canine thyroid, since comparable results were noted in studies of human, bovine or porcine thyroid slices. The protein kinase activity ratio (-cAMP/+cAMP) and glucose oxidation of TSH-Initial were also significantly increased above control following the final 10 min or 45 min incubations respectively. Addition of trypsin to the 3 h incubation abolished the subsequent increase in cAMP in TSH-Initial, while addition of TSH antiserum appreciably reduced this increase. These results are consistent with the persistent binding of biologically active TSH to thyroid. By contrast, evidence of similar persistent binding of PGE1 to thyroid, glucagon to liver, or parathyroid hormone to renal cortex was lacking when assessed by an identical experimental procedure. Differences between the duration of interaction of TSH and PGE1 with thyroid may be dependent or a more gradual dissociation to tissue bound TSH, a more rapid inactivation of bound-PGE1, or both.
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PMID:Evidence for persistent binding of biologically active thyrotropin to thyroid in vitro. 16 69

Glucagon activated adenylate cyclase in a homogenate of a pheochromocytoma over the concentration range 1 times 10 minus 8M to 1 times 10 minus 6M. Several other hormones including adrenocorticotropin, thyrotropin, parathyroid hormone and histamine were without effect. The tumor glucagon receptor was characterized and found to be similar in several ways to the glucagon receptor previously reported in normal tissue such as liver and heart. One, the receptor specifically bound 125-I-glucagon. Two, solubilization of the pheochromocytoma abolished glucagon-activation of the adenylate cyclase. Three, glucagon-responsiveness of the adenylate cyclase was partially restored by the addition of phosphatidylserine to the incubations. One major difference was observed between the glucagon receptor in tumor tissue and that in liver and heart, namely, a marked lability in 125-I-glucagon binding and adenylate cyclase activity. Within four days, despite storage in liquid nitrogen, 75% of the binding activity and all of the adenylate cyclase activity in the solubilized preparation were lost. The factor(s) responsible for this lability remains unidentified.
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PMID:Characterization of the glucagon receptor in a pheochromocytoma. 16 16

We have perfused isolated rat livers with hypocalcemic (4.4 mg 100 ml) Krebs-Ringer bicarbonate albumin buffer. After 15 min of perfusion, a substance appeared in the perfusate which decreased rat renal adenylate cyclase activation by parathyroid hormone (PTH). The material in the perfusate was purified greater than 50,000-fold by Bio-Gel P-10 chromatography. The purified antagonist decreased the activation of rat renal cortical adenylate cyclase by PTH, glucagon, and epinephrine 75 to 100%. Concentration response curves for each of the hormones indicated a noncompetitive interaction of the inhibitor with the hormone. The inhibition was not species-specific, as the activation of the parathyroid hormone-responsive adenylate cyclase in cat renal cortex was also abolished by the inhibitor from the perfused rat liver. The inhibitor is a peptide, Mr equal to similar to 1000, which is heat-stable, acid-stable, alkai-labile, and is destroyed by trypsin, leucine aminopeptidase, and elastase. It is not destroyed by phosphodiesterase, 5'-nucleotidase, alkaline phosphatase, neuraminidase, RNase, or phospholipase A. The inhibitor is not produced by isolated rat livers perfused with normocalcemic perfusion media. It is unclear whether the peptide is synthesized by the liver or whether it is a breakdown product of a larger peptide or protein in the liver. This is the first reported peptide inhibitor of adenylate cyclase.
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PMID:Isolation of a unique peptide inhibitor of hormone-responsive adenylate cyclase. 16 24

Purification of pork renal cortex membranes yielded a particulate adenylate cyclase retaining good sensitivity to stimulation by parathyroid hormone and glucagon and a modest but significant response to porcine calcitonin. Treatment of this partially purified membrane fraction with 0.5% Lubrol PX and 5 mM NaF released adenylate cyclase activity into a fraction which was not sedimented by centrifugation for 20 min at 37,000 X g or for 2 hours at 100,000 X g and passed through a Millipore filter (0.22 mum pore). This solubilized adenylate cyclase was stimulated by porcine calcitonin and NaF but not by parathyroid hormone or glucagon. On gel filtration (Sephadex G-200) in the presence of 1mM dithiothreitol and 5mM NaF, the major portion of the adenylate cyclase activity eluted with the void volume of the column and showed 2.0-fold stimulation with 10 muM calcitonin. Binding of 125I-labeled porcine calcitonin was demonstrated in the 37,000 X g and the 100,000 X g supernatants. From 74 to 86% of the observed binding could be blocked by the addition of unlabeled porcine calcitonin to the reaction mixture. Addition of salmon calcitonin, parathyroid hormone, or glucagon blocked only 12 to 18% of the binding. The dose-response curves for inhibition of binding of iodinated calcitonin by unlabeled calcitonin and the activation of adenylate cyclase by the hormone each showed 50% maximal effect at a concentration between 4.5 and 8 muM porcine calcitonin and maximal effect at a concentration between 33 and 66 muM porcine calcitonin.
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PMID:Solubilization of calcitonin-responsive renal cortical adenylate cyclase. 17 Feb 64

3', 5'-Adenosine monophosphate (cAMP) levels were determined in skeletal and heart muscle tissue of rats in chronic renal failure. Compared to normal animals no alteration in cAMP concentration was observed in heart muscle, whereas the cAMP levels in skeletal muscle were increased by 34%. This cAMP rise may be caused by the elevated plasma catecholamines, glucagon or parathyroid hormone levels in uraemia. The results suggest that the increased cAMP levels in skeletal muscle of rats in chronic renal failure contribute to the raised cAMP levels in the plasma.
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PMID:[Raised cAMP content of striated muscle in experimental chronic renal failure (author's transl)]. 17 Nov 31

Adenylate cyclase activity was measured in a crude particulate fraction of hyaline cartilage obtained from the xiphoid process of the rat. Bovine parathyroid hormone (PTH) at concentrations as low as 1.3 x 10(-7)M and porcine calcitonin (CT) at concentrations as low as 2.3 x 10(-5)M significantly increased adenylate cyclase activity. Glucagon, prostaglandin E1 (PGE1) and E2 (PG2), and epinephrine at concentrations of 10(-5)M also increased activity, whereas, no increased activity was seen with the additions of somatotrophin (10 mug/ml), PGF1alpha, PGF2alpha, or T3 at 10(-5)M. The combination of doses of PTH and CT, which individually produced maximal responses, was not additive. These data provide evidence that cartilage in growing rats responds directly to PTH and CT.
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PMID:Hormonal responsiveness of adenylate cyclase activity in cartilage. 17 93


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