Effects of anti-GLUT antibodies on glucose transport into human erythrocyte ghosts

Afzal, Iram; Browning, Joseph A.; Drew, C.; Ellory, J. C.; Naftalin, Richard J; Wilkins, Robert J.

doi:10.1016/j.bioelechem.2003.07.007

Cited by 7 publications

(4 citation statements)

References 19 publications

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“…The analysis here suggests that the unstirred layer affecting glucose transport resides within the body of the transporter and is largely controlled by the slow rate of glucose diffusion D 23 between the vestibule and cytosol. Similarly, ATP interactions at the endofacial surface of avian GLUT1 greatly retard net glucose influx in avian erythrocytes (29) and anti-GLUT1 antibodies binding to the endofacial C-terminal of GLUT1 retards glucose influx in human erythrocytes (30).…”

Section: Asymmetry Of Water and Glucose Flowsmentioning

confidence: 99%

Osmotic Water Transport with Glucose in GLUT2 and SGLT

Naftalin

2008

Biophysical Journal

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Carrier-mediated water cotransport is currently a favored explanation for water movement against an osmotic gradient. The vestibule within the central pore of Na+-dependent cotransporters or GLUT2 provides the necessary precondition for an osmotic mechanism, explaining this phenomenon without carriers. Simulating equilibrative glucose inflow via the narrow external orifice of GLUT2 raises vestibular tonicity relative to the external solution. Vestibular hypertonicity causes osmotic water inflow, which raises vestibular hydrostatic pressure and forces water, salt, and glucose into the outer cytosolic layer via its wide endofacial exit. Glucose uptake via GLUT2 also raises oocyte tonicity. Glucose exit from preloaded cells depletes the vestibule of glucose, making it hypotonic and thereby inducing water efflux. Inhibiting glucose exit with phloretin reestablishes vestibular hypertonicity, as it reequilibrates with the cytosolic glucose and net water inflow recommences. Simulated Na+-glucose cotransport demonstrates that active glucose accumulation within the vestibule generates water flows simultaneously with the onset of glucose flow and before any flow external to the transporter caused by hypertonicity in the outer cytosolic layers. The molar ratio of water/glucose flow is seen now to relate to the ratio of hydraulic and glucose permeability rather than to water storage capacity of putative water carriers.

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Section: Asymmetry Of Water and Glucose Flowsmentioning

confidence: 99%

Osmotic Water Transport with Glucose in GLUT2 and SGLT

Naftalin

2008

Biophysical Journal

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“…This difficulty was in large part due to the high degree of homology between the Glut-1 extracellular domains of diverse mammalian species and indeed, studies aimed at generating antibodies to all domains of Glut-1 concluded that the extracellular loops are non-antigenic [6,7]. Notably, this high conservation of Glut-1 is likely responsible for the ability of HTLV-1 to infect all tested vertebrate cell lines.…”

Section: Introductionmentioning

confidence: 99%

Isolated receptor binding domains of HTLV-1 and HTLV-2 envelopes bind Glut-1 on activated CD4+ and CD8+ T cells

et al. 2007

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Background: We previously identified the glucose transporter Glut-1, a member of the multimembrane-spanning facilitative nutrient transporter family, as a receptor for both HTLV-1 and HTLV-2. However, a recent report concluded that Glut-1 cannot serve as a receptor for HTLV-1 on CD4 T cells: This was based mainly on their inability to detect Glut-1 on this lymphocyte subset using the commercial antibody mAb1418. It was therefore of significant interest to thoroughly assess Glut-1 expression on CD4 and CD8 T cells, and its association with HTLV-1 and -2 envelope binding.

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“…Previous studies from this laboratory (5, 7, 8, 37–39) have shown that GLUT1 is a nucleotide binding protein, that ATP binding at an endofacial site increases the affinity of the exofacial site for sugars but reduces V max for sugar uptake, reduces cooperativity in cytochalasin B binding to GLUT1 but increases the affinity of the high affinity site for cytochalasin B. Other studies have shown that steroidal ligands (40, 41), caffeine and AMP (42) inhibit ATP binding to GLUT1 thereby altering the kinetics of glucose transport and cytochalasin B binding. It is possible therefore that activation of glucose influx at low cytochalasin B concentrations results from a complex interplay between cytochalasin B and nucleotide binding to GLUT1.…”

Section: Limitations Of the Analysismentioning

confidence: 95%

Kinetic Basis of Cis- and Trans-Allostery in GLUT1-Mediated Sugar Transport

et al. 2017

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A growing body of evidence demonstrates that GLUT1-mediated erythrocyte sugar transport is more complex than widely assumed and that contemporary interpretations of emergent GLUT1 structural data are incompatible with the available transport and biochemical data. This study examines the kinetic basis of one such incompatibility-transport allostery-and in doing so suggests how the results of studies examining GLUT1 structure and function may be reconciled. Three types of allostery are observed in GLUT1-mediated, human erythrocyte sugar transport: (1) exofacial cis-allostery in which low concentrations of extracellular inhibitors stimulate sugar uptake while high concentrations inhibit transport; (2) endofacial cis-allostery in which low concentrations of intracellular inhibitors enhance cytochalasin B binding to GLUT1 while high concentrations inhibit binding, and (3) trans-allostery in which low concentrations of ligands acting at one cell surface stimulate ligand binding at or sugar transport from the other surface while high concentrations inhibit these processes. We consider several kinetic models to account for these phenomena. Our results show that an inhibitor can only stimulate then inhibit sugar uptake if (1) the transporter binds two or more molecules of inhibitor; (2) high-affinity binding to the first site stimulates transport, and (3) low-affinity binding to the second site inhibits transport. Reviewing the available structural, transport, and ligand binding data, we propose that exofacial cis-allostery results from cross-talk between multiple, co-existent ligand interaction sites present in the exofacial cavity of each GLUT1 protein, whereas trans-allostery and endofacial cis-allostery require ligand-induced subunit-subunit interactions.

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Effects of anti-GLUT antibodies on glucose transport into human erythrocyte ghosts

Cited by 7 publications

References 19 publications

Osmotic Water Transport with Glucose in GLUT2 and SGLT

Osmotic Water Transport with Glucose in GLUT2 and SGLT

Isolated receptor binding domains of HTLV-1 and HTLV-2 envelopes bind Glut-1 on activated CD4+ and CD8+ T cells

Kinetic Basis of Cis- and Trans-Allostery in GLUT1-Mediated Sugar Transport

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