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INTESTINAL SUGAR TRANSPORT: STUDIES WITH ISOLATED PLASMA MEMBRANES fn1
Author(s) -
Hopfer U.,
SigristNelson K.,
Murer H.
Publication year - 1975
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.1975.tb31500.x
Subject(s) - membrane , transcellular , chemistry , cotransporter , biophysics , paracellular transport , glucose transporter , membrane transport , fructose , biochemistry , substrate (aquarium) , facilitated diffusion , biology , endocrinology , sodium , ecology , organic chemistry , insulin , permeability (electromagnetism)
The luminal and the contraluminal plasma membranes of small intestinal epithelial cells were isolated separately and in the form of membrane vesciles. In the luminal membrane distinct transport systems exist for D-fructose and for D-glucose and glucalogs as evidenced by stereospecificity for the substrate, counter- and cotransport phenomena, and inhibitor specificity. D-Glucose is taken up against a concentration gradient when energy is supplied in the form of an electrochemical Na+ gradient between medium and intravesicular membrane space. The contraluminal membrane also possesses a glucose transport system. However, it is sensitive to different inhibitors than the glucose transport in the luminal membrane. D-Glucose uptake by the contraluminal membrane is not enhanced by Na+ gradients and can be characterized as "facilitated diffusion." The studies with the isolated plasma membranes allow a description of transcellular D-glucose transport in terms of the translocation events across single membranes.