Insulin receptors and functions in normal and spontaneously transformed cloned rat hepatocytes

1979 ◽  
Vol 120 (1) ◽  
pp. 119-125 ◽  
Author(s):  
Barbara Petersen ◽  
Melvin Blecher
Keyword(s):  
Insulin Receptors ◽  
Rat Hepatocytes

scholarly journals Internalized insulin receptors are recycled to the cell surface in rat hepatocytes.

1982 ◽  
Vol 79 (19) ◽  
pp. 5921-5925 ◽  
Author(s):  
M. Fehlmann ◽  
J. L. Carpentier ◽  
E. Van Obberghen ◽  
P. Freychet ◽  
P. Thamm ◽  
...  
Keyword(s):  
Cell Surface ◽  
Insulin Receptors ◽  
Rat Hepatocytes

scholarly journals Insulin stimulates tyrosine phosphorylation of its receptor β-subunit in intact rat hepatocytes

1987 ◽  
Vol 241 (1) ◽  
pp. 99-104 ◽  
Author(s):  
R Ballotti ◽  
A Kowalski ◽  
M F White ◽  
Y Le Marchand-Brustel ◽  
E Van Obberghen
Keyword(s):  
Insulin Receptor ◽  
Tyrosine Phosphorylation ◽  
Biological Effects ◽  
Insulin Receptors ◽  
Rat Hepatocytes ◽  
Enzymic Activity ◽  
Beta Subunit ◽  
Isolated Rat Hepatocytes ◽  
Receptor Phosphorylation ◽  
Insulin Receptor Kinase

We studied the phosphorylation of the beta subunit of the insulin receptor in intact freshly isolated rat hepatocytes, labelled with [32P]Pi. Insulin receptors partially purified by wheat-germ agglutinin chromatography were immunoprecipitated with either antibodies to insulin receptor or antibodies to phosphotyrosine. Receptors derived from cells incubated in the absence of insulin contained only phosphoserine. Addition of insulin to hepatocytes led to a dose-dependent increase in receptor beta-subunit phosphorylation, with half-maximal stimulation being observed at 2 nM-insulin. Incubation of cells with 100 nM-insulin showed that, within 1 min of exposure to the hormone, maximal receptor phosphorylation occurred, which was followed by a slight decrease and then a plateau. This insulin-induced stimulation of its receptor phosphorylation was largely accounted for by phosphorylation on tyrosine residues. Sequential immunoprecipitation of receptor with anti-phosphotyrosine antibodies and with anti-receptor antibodies, and phosphoamino acid analysis of the immunoprecipitated receptors, revealed that receptors that failed to undergo tyrosine phosphorylation were phosphorylated on serine residues. The demonstration of a functional hormone-sensitive insulin-receptor kinase in normal cells strongly supports a role for this receptor enzymic activity in mediating biological effects of insulin.

Effect of down-regulation and return of insulin receptors on glycogen synthesis in cultured rat hepatocytes

1986 ◽  
Vol 888 (2) ◽  
pp. 191-198 ◽  
Author(s):  
Wolfgang E. Fleig ◽  
Gaby Nöther-Fleig ◽  
Sabine Steudter ◽  
Doris Enderle ◽  
Hans Ditschuneit
Keyword(s):  
Glycogen Synthesis ◽  
Insulin Receptors ◽  
Rat Hepatocytes ◽  
Down Regulation ◽  
Cultured Rat Hepatocytes

scholarly journals Cell-surface insulin receptor cycling and its implication in the glycogenic response in cultured foetal hepatocytes

1986 ◽  
Vol 239 (3) ◽  
pp. 609-615 ◽  
Author(s):  
P Soubigou ◽  
E Pringault ◽  
C Plas
Keyword(s):  
Cell Surface ◽  
Insulin Receptor ◽  
Polyacrylamide Gel Electrophoresis ◽  
Insulin Receptors ◽  
Rat Hepatocytes ◽  
Insulin Binding ◽  
Surface Proteins ◽  
Short Exposure ◽  
Intermittent Exposure ◽  
Initial Binding

The insulin-receptor cycle was investigated in cultured foetal rat hepatocytes by determining the variations in insulin-binding sites at the cell surface after short exposure to the hormone. Binding of 125I-insulin was measured at 4 degrees C after dissociation of prebound native insulin. Two protocols were used: exchange binding assay and binding after acid treatment; both gave the same results. Cell-surface 125I-insulin-receptor binding decreased sharply (by 40%) during the first 5 min of 10 nM-insulin exposure (t1/2 = 2 min) and remained practically constant thereafter; subsequent removal of the hormone restored the initial binding within 10 min. This fall-rise sequence corresponded to variations in the number of insulin receptors at the cell surface, with no detectable change in receptor affinity. The reversible translocation of insulin receptors from the cell surface to a compartment not accessible to insulin at 4 degrees C was hormone-concentration- and temperature-dependent. SDS/polyacrylamide-gel electrophoresis after cross-linking of bound 125I-insulin to cell-surface proteins with disuccinimidyl suberate showed that these variations were not associated with changes in Mr of binding components, in particular for the major labelled band of Mr 130,000. The insulin-receptor cycle could be repeated after intermittent exposure to insulin. Continuous or intermittent exposure to the hormone gave a similar glycogenic response, contrary to the partial effect of a unique short (5-20 min) exposure. A relationship could be established between the repetitive character of the rapid insulin-receptor cycle and the maximal expression of the biological effect in cultured foetal hepatocytes.

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