Demonstration of insulin induced enhancement of insulin dissociation from its receptor in H35 rat hepatoma cells in spite of a linear Scatchard plot.
The dissociation of insulin from its receptor has been reported to be enhanced in the presence of unlabeled insulin. This phenomenon has been used as a proof for the existence of negative cooperativity. However, when insulin degradation was inhibited by the use of a combination of bacitracin and chloroquine or prevented by a short incubation time in insulin binding studies in H35 rat hepatoma cells, linear Scatchard plots were obtained. This indicates that in the absence of insulin degradation negative cooperativity does not occur in these cells. Still the dissociation of insulin from its receptor was enhanced in the presence of 167 nM unlabeled insulin. This seriously questions the use of demonstration of insulin induced enhancement of insulin dissociation from its receptor as proof for the existence of negative cooperativity.
de Vries
C P
CP
Department of Endocrinology, Free University Hospital, Amsterdam, The Netherlands.
van Haeften
T W
TW
van der Veen
E A
EA
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D003627:Data Interpretation, Statistical; D007328:Insulin / Q000378:metabolism / Q000502:physiology*; D007457:Iodine Radioisotopes; D008114:Liver Neoplasms, Experimental / Q000378:metabolism*; D051381:Rats; D011972:Receptor, Insulin / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D007328:Insulin; D007457:Iodine Radioisotopes; D011972:Receptor, Insulin