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Medientyp:
E-Artikel
Titel:
Isolation and Characterization of a Highly Enriched Preparation of Receptosomes (Endosomes) from a Human Cell Line
Beteiligte:
Dickson, Robert B.;
Beguinot, Laura;
Hanover, John A.;
Richert, Nancy D.;
Willingham, Mark C.;
Pastan, Ira
Erschienen:
National Academy of Sciences of the United States of America, 1983
Erschienen in:Proceedings of the National Academy of Sciences of the United States of America
Sprache:
Englisch
ISSN:
0027-8424
Entstehung:
Anmerkungen:
Beschreibung:
<p>Receptor-mediated endocytosis proceeds by transfer of receptor--ligand complexes from clathrin-coated pits at the cell surface to uncoated endocytic vesicles termed receptosomes (or endosomes). These vesicles have now been purified more than 37-fold based on their content of newly internalized epidermal growth factor.<sup>125</sup>I-labeled EGF was bound to human KB carcinoma cells at 4 degrees C, and then the cells were warmed to 37 degrees C for 8 min and disrupted. The purification scheme involved density gradient centrifugation on colloidal silica and sucrose and gel filtration on Sephacryl S-1000. Relative to homogenate, receptosomes are enriched 4.3-fold in their cholesterol content and depleted in enzyme markers for plasma membranes (2- to 3-fold) and lysosomes (9-fold). Receptosomes have a polypeptide composition that is different from plasma membrane, lysosome, and other homogenate fractions. They are enriched in transferrin receptors (30-fold) and in unidentified M<sub>r</sub>70,000-75,000 glycoprotein(s); they contain phosphomannosyl receptors. They do not contain detectable amounts of clathrin.</p>