Insulin-induced internalization of the insulin receptor in the isolated rat adipose cell. Detection of both major receptor subunits following their biosynthetic labeling in culture

Diabetes ◽  
1984 ◽  
Vol 33 (1) ◽  
pp. 13-18 ◽  
Author(s):  
I. A. Simpson ◽  
J. A. Hedo ◽  
S. W. Cushman
Keyword(s):  
Insulin Receptor ◽  
Cell Detection ◽  
Adipose Cell ◽  
Isolated Rat

scholarly journals Calcium-dependence of insulin receptor phosphorylation

1983 ◽  
Vol 214 (2) ◽  
pp. 361-366 ◽  
Author(s):  
W E Plehwe ◽  
P F Williams ◽  
I D Caterson ◽  
L C Harrison ◽  
J R Turtle
Keyword(s):  
Membrane Protein ◽  
Insulin Receptor ◽  
Sodium Dodecyl Sulphate ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Beta Subunit ◽  
Receptor Phosphorylation ◽  
32P Incorporation ◽  
Isolated Rat

Phosphorylation of the insulin receptor of isolated rat adipocytes in response to insulin has been studied. Immunoprecipitation of adipocyte membrane protein demonstrated increased incorporation of 32P after exposure to insulin for 15 min, but this was dependent on the presence of physiological concentrations of Ca2+ and Mg2+. Autoradiography of solubilized immunoprecipitated membrane protein after sodium dodecyl sulphate/polyacrylamide-gel electrophoresis revealed that most of the 32P incorporation occurred in a band corresponding to Mr 95 000, which has been identified previously as the beta-subunit of the insulin receptor. 32P incorporation was inhibited by 2,4-dinitrophenol and trifluoperazine. It is suggested that insulin-receptor phosphorylation is an energy-requiring process that is Ca2+-dependent and may be modulated by calmodulin. Phosphorylation may proceed independently of glucose transport.

Propranolol prevents epinephrine from limiting insulin-stimulated muscle glucose uptake during contraction

2002 ◽  
Vol 93 (2) ◽  
pp. 697-704 ◽  
Author(s):  
Desmond G. Hunt ◽  
Zhenping Ding ◽  
John L. Ivy
Keyword(s):  
Insulin Receptor ◽  
Glucose Uptake ◽  
Kinase Activity ◽  
Pi3 Kinase ◽  
Insulin Receptor Substrate ◽  
Muscle Preparation ◽  
Acute Effects ◽  
Glucose Clearance ◽  
Slow Twitch ◽  
Isolated Rat

β-Blockade results in rapid glucose clearance and premature fatigue during exercise. To investigate the cause of this increased glucose clearance, we studied the acute effects of propranolol on insulin-stimulated muscle glucose uptake during contraction in the presence of epinephrine with an isolated rat muscle preparation. Glucose uptake increased in both fast- (epitrochlearis) and slow-twitch (soleus) muscle during insulin or contraction stimulation. In the presence of 24 nM epinephrine, glucose uptake during contraction was completely suppressed when insulin was present. This suppression of glucose uptake by epinephrine was accompanied by a decrease in insulin receptor substrate (IRS)-1-phosphatidylinositol 3 (PI3)-kinase activity. Propranolol had no direct effect on insulin-stimulated glucose uptake during contraction. However, epinephrine was ineffective in attenuating insulin-stimulated glucose uptake during contraction in the presence of propranolol. This ineffectiveness of epinephrine to suppress insulin-stimulated glucose uptake during contraction occurred in conjunction with its inability to completely suppress IRS-1-PI3-kinase activity. Results of this study indicate that the effectiveness of epinephrine to inhibit insulin-stimulated glucose uptake during contraction is severely diminished in muscle exposed to propranolol. Thus the increase in glucose clearance and premature fatigue associated with β-blockade could result from the inability of epinephrine to attenuate insulin-stimulated muscle glucose uptake.

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