Thermodynamic determination of the Na+: glucose coupling ratio for the human SGLT1 cotransporter

Biophysical Journal
X Z ChenJ Y Lapointe

Abstract

Phlorizin-sensitive currents mediated by a Na-glucose cotransporter were measured using intact or internally perfused Xenopus laevis oocytes expressing human SGLT1 cDNA. Using a two-microelectrode voltage clamp technique, measured reversal potentials (Vr) at high external alpha-methylglucose (alpha MG) concentrations were linearly related to In[alpha MG]o, and the observed slope of 26.1 +/- 0.8 mV/decade indicated a coupling ratio of 2.25 +/- 0.07 Na ions per alpha MG molecule. As [alpha MG]o decreased below 0.1 mM, Vr was no longer a linear function of In[alpha MG]o, in accordance with the suggested capacity of SGLT1 to carry Na in the absence of sugar (the "Na leak"). A generalized kinetic model for SGLT1 transport introduces a new parameter, Kc, which corresponds to the [alpha MG]o at which the Na leak is equal in magnitude to the coupled Na-alpha MG flux. Using this kinetic model, the curve of Vr as a function of In[alpha MG]o could be fitted over the entire range of [alpha MG]o if Kc is adjusted to 40 +/- 12 microM. Experiments using internally perfused oocytes revealed a number of previously unknown facets of SGLT1 transport. In the bilateral absence of alpha MG, the phlorizin-sensitive Na leak demonstrated a strong inwar...Continue Reading

Citations

Jul 12, 2005·The Journal of Membrane Biology·S EskandariD D F Loo
Mar 6, 2010·The Journal of Membrane Biology·Richard J Naftalin
Aug 1, 1996·Current Opinion in Cell Biology·E M WrightB A Hirayama
Jun 1, 1996·Current Opinion in Neurobiology·M S Sonders, S G Amara
Feb 1, 2006·The Journal of General Physiology·Dominique G GagnonJean-Yves Lapointe
Jan 16, 2007·Canadian Journal of Physiology and Pharmacology·Hovhannes J GukasyanRam Kannan
Oct 29, 2010·American Journal of Physiology. Cell Physiology·Charles S HummelErnest M Wright
Mar 29, 2001·Proceedings of the National Academy of Sciences of the United States of America·P P DuquetteJ Y Lapointe
Apr 20, 2004·The Journal of Physiology·Michael J CoadyJean-Yves Lapointe
Dec 23, 2004·The Journal of Physiology·Francis BourgeoisJean-Yves Lapointe
Mar 27, 2010·Biophysical Journal·Jean-Philippe LongpréJean-Yves Lapointe
Dec 31, 2010·Biophysical Journal·Jean-Philippe Longpré, Jean-Yves Lapointe
May 29, 2007·Biophysical Journal·Michael J CoadyJean-Yves Lapointe
Oct 31, 2006·Biophysical Journal·Dominique G GagnonJean-Yves Lapointe
Jan 26, 2017·ELife·Gabriel A FitzgeraldJoseph A Mindell
Jun 27, 2017·Biochimica Et Biophysica Acta. Biomembranes·Ofer ShamniShlomo Sasson
Aug 8, 1998·The Journal of Biological Chemistry·X Z ChenM A Hediger
Jun 9, 2017·American Journal of Physiology. Renal Physiology·Michael J CoadyJean-Yves Lapointe
Jul 23, 2002·The Journal of Biological Chemistry·Michael J CoadyJean-Yves Lapointe
Dec 23, 2004·American Journal of Physiology. Renal Physiology·Leila V VirkkiHeini Murer
May 10, 2005·The Journal of Biological Chemistry·Bernhard M Schmitt, Hermann Koepsell
Apr 25, 2007·Molecular Membrane Biology·Kyla M SmithJames D Young
Apr 30, 2011·Physiological Reviews·Ernest M WrightBruce A Hirayama
Jul 12, 2017·Proceedings. Mathematical, Physical, and Engineering Sciences·Peter J Gawthrop, Edmund J Crampin
Jan 31, 2014·American Journal of Physiology. Cell Physiology·Liangjie YinSadasivan Vidyasagar
Jun 20, 2014·American Journal of Physiology. Cell Physiology·Louis J SassevilleJean-Yves Lapointe
Nov 27, 1999·The Journal of Biological Chemistry·X Z ChenM A Hediger
Jan 23, 1999·The Journal of Biological Chemistry·X Z ChenM A Hediger
Aug 9, 2020·Pflügers Archiv : European journal of physiology·Gergely GyimesiMatthias A Hediger
Apr 13, 1999·The American Journal of Physiology·I C ForsterS Eskandari

❮ Previous
Next ❯

Related Concepts

Trending Feeds

COVID-19

Coronaviruses encompass a large family of viruses that cause the common cold as well as more serious diseases, such as the ongoing outbreak of coronavirus disease 2019 (COVID-19; formally known as 2019-nCoV). Coronaviruses can spread from animals to humans; symptoms include fever, cough, shortness of breath, and breathing difficulties; in more severe cases, infection can lead to death. This feed covers recent research on COVID-19.

Blastomycosis

Blastomycosis fungal infections spread through inhaling Blastomyces dermatitidis spores. Discover the latest research on blastomycosis fungal infections here.

Nuclear Pore Complex in ALS/FTD

Alterations in nucleocytoplasmic transport, controlled by the nuclear pore complex, may be involved in the pathomechanism underlying multiple neurodegenerative diseases including Amyotrophic Lateral Sclerosis and Frontotemporal Dementia. Here is the latest research on the nuclear pore complex in ALS and FTD.

Applications of Molecular Barcoding

The concept of molecular barcoding is that each original DNA or RNA molecule is attached to a unique sequence barcode. Sequence reads having different barcodes represent different original molecules, while sequence reads having the same barcode are results of PCR duplication from one original molecule. Discover the latest research on molecular barcoding here.

Chronic Fatigue Syndrome

Chronic fatigue syndrome is a disease characterized by unexplained disabling fatigue; the pathology of which is incompletely understood. Discover the latest research on chronic fatigue syndrome here.

Evolution of Pluripotency

Pluripotency refers to the ability of a cell to develop into three primary germ cell layers of the embryo. This feed focuses on the mechanisms that underlie the evolution of pluripotency. Here is the latest research.

Position Effect Variegation

Position Effect Variagation occurs when a gene is inactivated due to its positioning near heterochromatic regions within a chromosome. Discover the latest research on Position Effect Variagation here.

STING Receptor Agonists

Stimulator of IFN genes (STING) are a group of transmembrane proteins that are involved in the induction of type I interferon that is important in the innate immune response. The stimulation of STING has been an active area of research in the treatment of cancer and infectious diseases. Here is the latest research on STING receptor agonists.

Microbicide

Microbicides are products that can be applied to vaginal or rectal mucosal surfaces with the goal of preventing, or at least significantly reducing, the transmission of sexually transmitted infections. Here is the latest research on microbicides.