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Title: Quantitative studies of pinocytosis. II. Kinetics of protein uptake and digestion by rat yolk sac cultured in vitro
Authors: Williams, Kenneth E.
Kidston, Elizabeth M.
Beck, Felix
Lloyd, John B.
First Published: 1-Jan-1975
Publisher: Rockefeller University Press
Citation: The Journal of Cell Biology, 1975 vol. 64 no. 1 123-134
Abstract: Pinocytic uptake of 125I-labeled bovine serum albumin by 17.5-day rat visceral yolk sac cultured in vitro has been examined. Uptake was followed by intracellular digestion and, after an initial period, the content of radioactivity in the tissue itself remained constant during the incubation. Radiolabel was returned to the culture medium predominantly as (125I)iodotyrosine; exocytosis of undigested protein did not occur. The rate of uptake of labeled protein, which was constant within an experiment and reproducible between experiments, was much higher than that of a nondigestible macromolecule, 125I-labeled polyvinylpyrrolidone. The higher rate of uptake was a consequence of the protein entering the cells chiefly by adsorption to the plasma membrane being internalized; 125I-labeled albumin did not stimualte, nor did 125I-labeled polyvinylpyrrolidone inhibit pinocytosis. Different preparations of 125I-labeled albumin had characteristically different rates of uptake, probably reflecting differences in affinity for plasma membrane receptors. The physiological significance of the findings is discussed.
DOI Link: 10.1083/jcb.64.1.123
ISSN: 0021-9525
eISSN: 1540-8140
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported license as described at and
Appears in Collections:Published Articles, College of Medicine, Biological Sciences and Psychology

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