Insulin-like growth factor 1 and insulin reduce epidermal growth factor binding to Swiss 3T3 cells by an indirect mechanism that is apparently independent of protein kinase C.
Insulin-like growth factor 1 and insulin reduced the binding of 125I-labelled epidermal growth factor (125I-EGF) to Swiss 3T3 cells by 15-20% at 37 degrees C, but not at 4 degrees C. Scatchard analysis indicated that IGF-1 and insulin affected the higher-affinity component of EGF binding, an effect previously associated with the activation of protein kinase C. However, the inhibition of 125I-EGF binding by IGF-1 and insulin was increased, not reduced, when the cells were treated with high concentrations of phorbol esters to down-modulate protein kinase C. We suggest that IGF-1 and insulin activate a protein kinase with similar or overlapping specificity to that of protein kinase C.
Corps
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Department of Biochemistry, AFRC Institute of Animal Physiology & Genetics Research, Babraham, Cambridge, England.
Brown
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D000818:Animals; D002478:Cells, Cultured; D004815:Epidermal Growth Factor / Q000378:metabolism*; D066246:ErbB Receptors / Q000187:drug effects / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007700:Kinetics; D051379:Mice; D011493:Protein Kinase C / Q000378:metabolism*; D013002:Somatomedins / Q000494:pharmacology*
D007328:Insulin; D013002:Somatomedins; D004815:Epidermal Growth Factor; D007334:Insulin-Like Growth Factor I; D066246:ErbB Receptors; D011493:Protein Kinase C