Receptor-mediated endocytosis of transferrin and the uptake of fe in K562 cells: identification of a nonlysosomal acidic compartment.

J Van Renswoude, KR Bridges… - Proceedings of the …, 1982 - National Acad Sciences
J Van Renswoude, KR Bridges, JB Harford, RD Klausner
Proceedings of the National Academy of Sciences, 1982National Acad Sciences
At physiological temperature, the Fe-carrier transferrin is taken up by K562 human
erythroleukemia cells through receptor-mediated endocytosis. Both ligand (now minus Fe)
and receptor recycle back to the cell surface where the receptor is rapidly reutilized. After
endocytosis, transferrin becomes transiently lodged within an acidic compartment inside the
cell, as judged by the changed spectral characteristics and quantum yield of fluorescein
isothiocyanate-labeled transferrin that is cell-associated at 37 degrees C. Upon binding to …
At physiological temperature, the Fe-carrier transferrin is taken up by K562 human erythroleukemia cells through receptor-mediated endocytosis. Both ligand (now minus Fe) and receptor recycle back to the cell surface where the receptor is rapidly reutilized. After endocytosis, transferrin becomes transiently lodged within an acidic compartment inside the cell, as judged by the changed spectral characteristics and quantum yield of fluorescein isothiocyanate-labeled transferrin that is cell-associated at 37 degrees C. Upon binding to transferrin, anti-fluorescein antibody strongly quenches the emission of the fluorescein-labeled residues on the protein and is used to assess whether the transferrin is at the cell surface (incubation at 0 degrees C) or mainly internalized into the cell (incubation at 37 degrees C). Using Percoll gradient fractionation of postnuclear supernatants, we show that the acidic compartment is not the lysosomal compartment.
National Acad Sciences