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M Wellner

Publications and source records attributed to M Wellner.

23 records · Page 2Linked to original sources
PubMed1993

GTP analogs suppress uptake but not transport of D-glucose analogs in Glut1 glucose transporter-expressing Xenopus oocytes.

A Xenopus oocyte expression-co-injection system was used to study the influence of guanine nucleotides on D-glucose uptake. GTP analogs like GTP gamma S and GppNHp had no effect on 3-O-methylglucose transport determined by zero-trans uptake or equilibrium exchange, but suppressed 2-deoxyglucose uptake into Glut1 glucose transporter-expressing oocytes by up to 86%. Both GTP analogs showed concentration dependence of their effectiveness, with GTP gamma S being more potent than GppNHp. No statistically significant differences were observed between groups of oocytes co-injected with water or GDP beta S (250 and 500 microM intracellular concentration). Glut1 transporter expression in plasma membrane was not different between water or GTP gamma S-co-injected oocytes. Thus, inhibition of hexokinase catalytic activity is the most likely causative factor for down-regulation of 2-deoxyglucose uptake.

Animals↗
PubMed1992

The differential role of Cys-421 and Cys-429 of the Glut1 glucose transporter in transport inhibition by p-chloromercuribenzenesulfonic acid (pCMBS) or cytochalasin B (CB).

Cys-421 and Cys-429 of Glut1 were replaced by site-directed mutagenesis in order to investigate their involvement in basal glucose transport and transport inhibition. Neither of the two cysteine residues was essential for basal 2-deoxy-D-glucose uptake in Xenopus oocytes expressing the respective mutant M421 and M429. If applied from the external side, the poorly permeable sulfhydryl-reactive agent pCMBS inhibited 2-deoxy-D-glucose uptake of Glut1- and M421-expressing Xenopus oocytes but failed to affect uptake of the Cys-429 mutant. This is in agreement with the proposed two-dimensional model of Glut1 confirming that Cys-429 is the only residue exposed to the surface of the plasma membrane. The replacement of Cys-421 at the exofacial end of helix eleven caused a partial protection of 3-O-methylglucose transport inhibition by CB; this residue may thus be involved in stabilizing an adjacent local tertiary structure necessary for the full activity of this inhibitor.

4-Chloromercuribenzenesulfonate↗