Cell-Free Systems for Studying the Pathway of Receptor-Mediated Endocytosis
Receptor-mediated endocytosis is a process used by cells to take up nutritionally important molecules such as transferrin (Octave et al., 1983). Transferrin receptors provide the means of taking transferrin into cells because they both bind transferrin tightly and are themselves located in coated pits, presumably because of certain features in the cytoplasmic tail (see Glickman et al., 1989). Coated pits invaginate, presumably by rearrangement of the clathrin coat (Pearse and Crowther, 1987), and eventually undergo membrane scission to form coated vesicles (Hopkins and Trowbridge, 1983). After uncoating (Rothman and Schmid, 1986) they deliver their contents to endosomes (Helenius et al., 1983) and the low pH within these organelles causes the iron to dissociate from the transferrin (Aisen and Listowsky, 1980). Apo-transferrin, still bound to the receptors, then recycles back to the cell surface (Klausner et al., 1983; Dautry-Varsat et al., 1983) where it is released allowing further molecules of transferrin to bind and continue the cycle bringing iron into the cell.
KeywordsA431 Cell Break Cell Transferrin Receptor Donor Activity Coated Vesicle
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