Quantitative studies of pinocytosis. II. Kinetics of protein uptake and digestion by rat yolk sac cultured in vitro
نویسندگان
چکیده
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.
منابع مشابه
Quantitative studies of pinocytosis. I. Kinetics of uptake of (125I)polyvinylpyrrolidone by rat yolk sac cultured in vitro
A method is described for the in vitro culture of 17.5-day rat visceral yolk sac. Tissue survival was good as judged by light and electron microscopy. The rate of pinocytic uptake of 125I-labeled polyvinylpyrrolidone by the tissue was constant both within and between experiments. Within the concentration range 0.15-24 mug/ml, the 125I-labeled polyvinylpyrrolidone neither stimulated nor inhibite...
متن کاملThe effect of teratogenic antiserum on yolk-sac function in rat embryos cultured in vitro.
The teratogenicity of rabbit anti-rat visceral yolk-sac antiserum, injected into pregnant rats at either 8-5 or 9-5 days of gestation, has been confirmed. Normal rabbit serum was found not to be teratogenic. When conceptuses from 9-5-day pregnant rats were cultured for 48 h in heat-denatured homologous serum, to which antiserum was added for the final (or the penultimate) 6 h of culture, embryo...
متن کاملQUANTITATIVE STUDIES OF PINOCYTOSIS I. Kinetics of Uptake of [~sI]Polyvinylpyrrolidone by Rat Yolk Sac Cultured In Vitro
A method is described for the in vitro culture of 17.5-day rat visceral yolk sac. Tissue survival was good as judged by light and electron microscopy. The rate of pinocytic uptake of ~25I-labeled polyvinylpyrrolidone by the tissue was constant both within and between experiments. Within the concentrat ion range 0 .15-24 ~tg/ml, the a2~I-labeled polyvinylpyrrolidone neither stimulated nor inhibi...
متن کاملEthanol-induced inhibition of pinocytosis and proteoiysis in rat yolk sac in vitro
Pinocytic capture of I-labelled polyvinylpyrrolidone and of formaldehyde-denatured ^I-labelled bovine serum albumin by 17-5-day rat visceral yolk sacs incubated in vitro was rapidly and strongly inhibited by low concentrations (001 and 005%, v/v) of ethanol. The induced inhibition of pinocytosis was readily reversible, but a marked lag was observed before ethanol-exposed tissue regained its ful...
متن کاملThe role of the visceral yolk sac in mediating protein utilization by rat embryos cultured in vitro.
Conceptuses from 9-5-day pregnant rats have been cultured for 48 h in heat-inactivated homologous serum. Embryonic development was normal. The protein contents of embryos and visceral yolk sacs after different periods of culture were recorded. When I-labelled polyvinylpyrrolidone or [H]dextran were added to the culture serum, radioactivity was accumulated by the yolk sac, but only background le...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- The Journal of Cell Biology
دوره 64 شماره
صفحات -
تاریخ انتشار 1975