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.
Wellner
M
M
Institut für Pharmakologie, Freien Universität Berlin, Germany.
Mueckler
M M
MM
Keller
K
K
D000818:Animals; D002462:Cell Membrane; D005260:Female; D015870:Gene Expression; D005947:Glucose / Q000031:analogs & derivatives / Q000378:metabolism*; D051272:Glucose Transporter Type 1; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology*; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology*; D006593:Hexokinase / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D014981:Xenopus
D051272:Glucose Transporter Type 1; D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; D006165:Guanylyl Imidodiphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006593:Hexokinase; D005947:Glucose