Characterization of a Na+/glucose cotransporter cloned from rabbit small intestine

Ikeda, Tyson S.; Hwang, E. Shelley; Coady, Michael J.; Hirayama, Bruce A.; Hediger, Matthias A.; Wright, Ernest M.

doi:10.1007/bf01870995

Cited by 163 publications

(98 citation statements)

References 18 publications

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“…Similar results were obtained for sugar competition of αMDG uptake into inside-out membrane vesicles expressing hSGLT1 (αMDG > 3-O-methyl-glucose ~ D-galactose > D-glucose; Quick & Tomasevic & Wright, 2003). In contrast, the relative affinities for sugar cotransport in the forward direction by rabbit, rat and human isoforms of SGLT1 is αMDG ~ D-glucosẽ D-galactose > 3-O-methyl-glucose (Ikeda et al, 1989;Birnir et al, 1991;PanayatovaHeiermann, Loo & Wright, 1995;Hirayama et al, 1996;Díez-Sampedro et al, 2001). The differences in sugar affinity and selectivity for cotranport in the two directions under the same driving forces suggest differences in the architecture of the outward-and inwardfacing sugar binding sites.…”

Section: Discussionsupporting

confidence: 69%

Kinetics of the Reverse Mode of the Na+/Glucose Cotransporter

2005

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This study investigates the reverse mode of the Na + /glucose cotransporter (SGLT1). In giant excised inside-out membrane patches from Xenopus laevis oocytes expressing rabbit SGLT1, application of α-methyl-D-glucopyranoside (αMDG) to the cytoplasmic solution induced an outward current from cytosolic to external membrane surface. The outward current was Na + -and sugar-dependent, and was blocked by phlorizin, a specific inhibitor of SGLT1. The currentvoltage relationship saturated at positive membrane voltages (30-50 mV), and approached zero at − 150 mV. The half-maximal concentration for αMDG-evoked outward current ( ) was 35 mM (at 0 mV). In comparison, for forward sugar transport was 0.15 mM (at 0 mV). was similar for forward and reverse transport (≈35 mM at 0 mV). Specificity of SGLT1 for reverse transport was: αMDG (1.0) > D-galactose (0.84) > 3-O-methyl-glucose (0.55) > D-glucose (0.38), whereas for forward transport, specificity was: αMDG ≈ D-glucose ≈ D-galactose > 3-Omethyl-glucose. Thus there is an asymmetry in sugar kinetics and specificity between forward and reverse modes. Computer simulations showed that a 6-state kinetic model for SGLT1 can account for Na + /sugar cotransport and its voltage dependence in both the forward and reverse modes at saturating sodium concentrations. Our data indicate that under physiological conditions, the transporter is poised to accumulate sugar efficiently in the enterocyte.

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Section: Discussionsupporting

confidence: 69%

Kinetics of the Reverse Mode of the Na+/Glucose Cotransporter

2005

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“…In a series of experiments in 15 gM taurine, the uptake of [3H]taurine in cRNA-injected oocytes (using methods described in [14]) was 11 +2 nM/h (n=8), and was 20-fold higher than in noninjected oocytes (0.5 + 0.1 nM/h, n = 10), thus confirming that taurine is transported into cRNA-injected oocytes. Electrophysiological measurements were undertaken 5-7 days post-cRNA injection, using a two-electrode voltage clamp [11].…”

Section: Methodsmentioning

confidence: 65%

Regulation of the mouse retinal taurine transporter (TAUT) by protein kinases inXenopusoocytes

et al. 1996

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“…The size sieving effect also explains, in part, why D-glucose (M r =180) absorption was higher than 3OMD-glucose (M r =194) absorption. Absorption of D-glucose by transporter-mediated means is also likely higher than 3OMD-glucose because of higher affinity for the glucose transporter (Ikeda et al, 1989;Kimmich, 1981).…”

Section: Research Articlementioning

confidence: 99%

High paracellular nutrient absorption in intact bats is associated with high paracellular permeability in perfused intestinal segments

Brun

Price

Gontero-Fourcade

et al. 2014

Journal of Experimental Biology

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Water-soluble nutrients are absorbed by the small intestine via transcellular and paracellular mechanisms. Based on a few previous studies, the capacity for paracellular nutrient absorption seems greater in flying mammals than in nonflying mammals, but there has been little investigation of the mechanisms driving this difference. Therefore, we studied three species each of bats (Artibeus lituratus, Sturnira lilium and Carollia perspicillata) and nonflying mammals (Akodon montensis, Mus musculus and Rattus norvegicus). Using standard pharmacokinetic techniques in intact animals, we confirmed the greater paracellular nutrient absorption in the fliers, comparing one species in each group. Then we conducted in situ intestinal perfusions on individuals of all species. In both approaches, we measured the absorption of 3OMD-glucose, a nonmetabolizable glucose analog absorbed both paracellularly and transcellularly, as well as L-arabinose, which has no mediated transport. Fractional absorption of L-arabinose was three times higher in the bat (S. lilium: 1.2±0.24) than in the rodent (A. montensis: 0.35±0.04), whereas fractional absorption of 3OMD-glucose was complete in both species (1.46±0.4 and 0.97±0.12, respectively). In agreement, bats exhibited two to 12 times higher L-arabinose clearance per square centimeter nominal surface area than rodents in intestinal perfusions. Using Larabinose, we estimated that the contribution of the paracellular pathway to total glucose absorption was higher in all three bats (109-137%) than in the rodents (13-39%). These findings contribute to an emerging picture that reliance on the paracellular pathway for nutrient absorption is much greater in bats relative to nonflying mammals and that this difference is driven by differences in intestinal permeability to nutrient-sized molecules.

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Characterization of a Na+/glucose cotransporter cloned from rabbit small intestine

Cited by 163 publications

References 18 publications

Kinetics of the Reverse Mode of the Na+/Glucose Cotransporter

Kinetics of the Reverse Mode of the Na+/Glucose Cotransporter

Regulation of the mouse retinal taurine transporter (TAUT) by protein kinases inXenopusoocytes

High paracellular nutrient absorption in intact bats is associated with high paracellular permeability in perfused intestinal segments

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