Abstract
Uptake studies of simple sugars were performed on a membrane fractions containing osmotically active vesicles prepared from normal human kidney cortex. The uptake of D-glucose was found to be sodium-dependent and phlorizin-sensitive. The specificity of the D-glucose transport mechanism is such that it is shared by alpha-methyl-D-glucoside, D-galactose, and 5-thio-D-glucose, while 2-deoxy-D-glucose, 3-O-methyl-D-glucose, D-mannose, and D-fructose show little, if any, affinity. Measurement of the sodium-dependent component of the initial D-glucose uptake as a function of glucose concentration resulted in a curvilinear Scatchard plot, indicating the possibility of cooperative effects, or alternatively, the existence of two (or more) sodium-dependent D-glucose transporters. In the case of two transporters, we estimate that Km congruent to 0.3 mM and Vmax congruent to 2.5 nmol/min per mg of protein for the "high-affinity transporter," and Km approximately 6 mM and Vmax approximately 8 nmol/min per mg of protein for the "low-affinity transporter." These specificity and kinetic properties strongly suggest that the sodium-dependent D-glucose transport mechanism characterized in our studies is localized to the brush border of the proximal tubule.
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Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Beck J. C., Sacktor B. Energetics of the Na+-dependent transport of D-glucose in renal brush border membrane vesicles. J Biol Chem. 1975 Nov 25;250(22):8674–8680. [PubMed] [Google Scholar]
- Forstner G. G., Sabesin S. M., Isselbacher K. J. Rat intestinal microvillus membranes. Purification and biochemical characterization. Biochem J. 1968 Jan;106(2):381–390. doi: 10.1042/bj1060381. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Heidrich H. G., Kinne R., Kinne-Saffran E., Hannig K. The polarity of the proximal tubule cell in rat kidney. Different surface charges for the brush-border microvilli and plasma membranes from the basal infoldings. J Cell Biol. 1972 Aug;54(2):232–245. doi: 10.1083/jcb.54.2.232. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hopfer U. INtestinal sugar transport: studies with isolated plasma membranes. Ann N Y Acad Sci. 1975 Dec 30;264:414–427. doi: 10.1111/j.1749-6632.1975.tb31500.x. [DOI] [PubMed] [Google Scholar]
- LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
- Murer H., Hopfer U. Demonstration of electrogenic Na+-dependent D-glucose transport in intestinal brush border membranes. Proc Natl Acad Sci U S A. 1974 Feb;71(2):484–488. doi: 10.1073/pnas.71.2.484. [DOI] [PMC free article] [PubMed] [Google Scholar]
- PENNINGTON R. J. Biochemistry of dystrophic muscle. Mitochondrial succinate-tetrazolium reductase and adenosine triphosphatase. Biochem J. 1961 Sep;80:649–654. doi: 10.1042/bj0800649. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schmitz J., Preiser H., Maestracci D., Ghosh B. K., Cerda J. J., Crane R. K. Purification of the human intestinal brush border membrane. Biochim Biophys Acta. 1973 Sep 27;323(1):98–112. doi: 10.1016/0005-2736(73)90434-3. [DOI] [PubMed] [Google Scholar]
- Silverman M. Glucose transport in the kidney. Biochim Biophys Acta. 1976 Dec 14;457(3-4):303–351. doi: 10.1016/0304-4157(76)90003-4. [DOI] [PubMed] [Google Scholar]