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.
Wellner
M
M
Institut für Pharmakologie, Freien Universität Berlin, Germany.
Monden
I
I
Keller
K
K
D002731:4-Chloromercuribenzenesulfonate / Q000494:pharmacology*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D003545:Cysteine / Q000378:metabolism / Q000502:physiology*; D003571:Cytochalasin B / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D051272:Glucose Transporter Type 1; D009004:Monosaccharide Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D014981:Xenopus
D051272:Glucose Transporter Type 1; D009004:Monosaccharide Transport Proteins; D003571:Cytochalasin B; D002731:4-Chloromercuribenzenesulfonate; D005947:Glucose; D003545:Cysteine