ArticleBiophysical journal1995
Thermodynamic determination of the Na+: glucose coupling ratio for the human SGLT1 cotransporter.
Article in Biophysical journal, 1995. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 32 papers.
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Who cites it
32 citing papers in PubMed, 86 citations in OpenAlex.
- Energy-based bond graph models of glucose transport with SLC transporters.Biophysical journal · 2025Article
- The role of NHE3 (Slc9a3) in oxalate and sodium transport by mouse intestine and regulation by cAMP.Physiological reports · 2021Article
- Network Thermodynamical Modeling of Bioelectrical Systems: A Bond Graph Approach.Bioelectricity · 2021Article
- Sodium-coupled glucose transport, the SLC5 family, and therapeutically relevant inhibitors: from molecular discovery to clinical application.Pflugers Archiv : European journal of physiology · 2020Review
- Structural biology workflow for the expression and characterization of functional human sodium glucose transporter type 1 in Pichia pastoris.Scientific reports · 2019Article
- The molecular mechanism of SLC34 proteins: insights from two decades of transport assays and structure-function studies.Pflugers Archiv : European journal of physiology · 2019Review
- Article
- Energy-based analysis of biomolecular pathways.Proceedings. Mathematical, physical, and engineering sciences · 2017Article
- Glucose Transporters at the Blood-Brain Barrier: Function, Regulation and Gateways for Drug Delivery.Molecular neurobiology · 2017Review
- Article
- Pathophysiology of Intestinal NaCellular and molecular gastroenterology and hepatology · 2017Article
- The transport mechanism of the human sodium/myo-inositol transporter 2 (SMIT2/SGLT6), a member of the LeuT structural family.American journal of physiology. Cell physiology · 2014Article
- Determination of the Na(+)/glucose cotransporter (SGLT1) turnover rate using the ion-trap technique.Biophysical journal · 2011Article
- Glucose transport by human renal Na+/D-glucose cotransporters SGLT1 and SGLT2.American journal of physiology. Cell physiology · 2011Article
- Review
- Reassessment of models of facilitated transport and cotransport.The Journal of membrane biology · 2010Article
- The actual ionic nature of the leak current through the Na+/glucose cotransporter SGLT1.Biophysical journal · 2010Article
- Establishing a definitive stoichiometry for the Na+/monocarboxylate cotransporter SMCT1.Biophysical journal · 2007Article
- Effect of substrate on the pre-steady-state kinetics of the Na(+)/glucose cotransporter.Biophysical journal · 2007Article
- Identification of a disulfide bridge linking the fourth and the seventh extracellular loops of the Na+/glucose cotransporter.The Journal of general physiology · 2006Article
Corrections and comments
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Authors and funding
5 authors at 1 institution in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
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 inward rectification. The affinity of alpha MG for its internal site was low; the Km was estimated to be between 25 and 50 mM, an order of magnitude higher than that found for the extracellular site. Furthermore, Vr determinations at varying alpha MG concentrations indicate a transport stoichiometry of 2 Na ions per alpha MG molecule: the slope of Vr versus In[alpha MG]o averaged 30.0 +/- 0.7 mV/decade (corresponding to a stoichiometry of 1.96 +/- 0.04 Na ions per alpha MG molecule) whenever [alpha MG]o was higher than 0.1 mM. These direct observations firmly establish that Na ions can utilize the SGLT1 protein to cross the membrane either alone or in a coupled manner with a stoichiometry of 2 Na ions per sugar, molecule.
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