Diabetes, Vol 34, Issue 10 1002-1007, Copyright © 1985 by American Diabetes Association
Redistribution of 125I-insulin on the surface of rat hepatocytes as a function of dissociation time
JL Carpentier, M Fehlmann, E Van Obberghen, P Gorden and L Orci
In the present experiments, we have correlated the distribution of
125I-insulin on the surface of rat hepatocytes with the dissociation of
125I-insulin from the cell. When 125I-insulin interacts with isolated rat
hepatocytes at 15 degrees C, an increasing proportion of the bound ligand
becomes nondissociable under the influence of acid pH (6.0), trypsin (0.5
mg/ml), or an excess of unlabeled insulin (10(-6) M). Under these
conditions, only a small percentage of the labeled material is internalized
as determined by quantitative electron microscope (EM) autoradiography.
This progressive nondissociability of the ligand parallels its movement
from microvilli to coated pits and its progressive concentration in these
later surface specializations. These data suggest that receptors in
different domains of the plasma membrane may have different dissociation
rates for the ligand.