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Am J Physiol Renal Physiol. 2017 Aug 1;313(2):F467-F474. doi: 10.1152/ajprenal.00628.2016. Epub 2017 Jun 7.

Characterization of the transport activity of SGLT2/MAP17, the renal low-affinity Na+-glucose cotransporter.

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Groupe d'Étude des Protéines Membranaires, Département de Physique, Université de Montréal, Montréal, Québec, Canada.
Groupe d'Étude des Protéines Membranaires, Département de Physique, Université de Montréal, Montréal, Québec, Canada


The cotransporter SGLT2 is responsible for 90% of renal glucose reabsorption, and we recently showed that MAP17 appears to work as a required β-subunit. We report in the present study a detailed functional characterization of human SGLT2 in coexpression with human MAP17 in Xenopus laevis oocytes. Addition of external glucose generates a large inward current in the presence of Na, confirming an electrogenic transport mechanism. At a membrane potential of -50 mV, SGLT2 affinity constants for glucose and Na are 3.4 ± 0.4 and 18 ± 6 mM, respectively. The change in the reversal potential of the cotransport current as a function of external glucose concentration clearly confirms a 1:1 Na-to-glucose transport stoichiometry. SGLT2 is selective for glucose and α-methylglucose but also transports, to a lesser extent, galactose and 3-O-methylglucose. SGLT2 can be inhibited in a competitive manner by phlorizin (Ki = 31 ± 4 nM) and by dapagliflozin (Ki = 0.75 ± 0.3 nM). Similarly to SGLT1, SGLT2 can be activated by Na, Li, and protons. Pre-steady-state currents for SGLT2 do exist but are small in amplitude and relatively fast (a time constant of ~2 ms). The leak current defined as the phlorizin-sensitive current in the absence of substrate was extremely small in the case of SGLT2. In summary, in comparison with SGLT1, SGLT2 has a lower affinity for glucose, a transport stoichiometry of 1:1, very small pre-steady-state and leak currents, a 10-fold higher affinity for phlorizin, and an affinity for dapagliflozin in the subnanomolar range.


dapagliflozin; electrophysiology; glucose transport; kinetics; transport properties

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