The Journal of Cell Biology, Vol 102, 989-996, Copyright © 1986 by The Rockefeller University Press
Intracellular pathway followed by the insulin receptor covalently coupled to 125I-photoreactive insulin during internalization and recycling
JL Carpentier, H Gazzano, E Van Obberghen, M Fehlmann, P Freychet and L Orci
After it interacts with a specific receptor on the cell surface, insulin is
internalized in its target cell by an adsorptive endocytotic process and
eventually degraded in lysosomes. It was also recently shown that the
initial surface interaction between the hormone and its receptor is
followed by an internalization of the receptor, which later is recycled
back to the cell surface. In the present study the insulin receptor was
tagged with a 125I-photoreactive insulin analogue that can be covalently
coupled to the insulin receptor by ultraviolet irradiation. Using this tool
we could trace by quantitative electron microscope autoradiography the
intracellular pathway followed by this labeled receptor. The quantitative
analysis of the intracellular distribution of the labeled material as a
function of incubation time at 37 degrees C supports the following sequence
of events: association first with clear vesicles, second with
multivesicular bodies, third with dense bodies, and fourth, a return to the
cell surface via clear vesicles. This insulin receptor recycling process is
inhibited by monensin but unaffected by cycloheximide.
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