title: The glucose-6-phosphate transport is not mediated by a glucose-6-phosphate/phosphate exchange in liver microsomes.
abstract: A phosphate-linked antiporter activity of the glucose-6-phosphate transporter (G6PT) has been recently described in liposomes including the reconstituded transporter protein. We directly investigated the mechanism of glucose-6-phosphate (G6P) transport in rat liver microsomal vesicles. Pre-loading with inorganic phosphate (Pi) did not stimulate G6P or Pi microsomal inward transport. Pi efflux from pre-loaded microsomes could not be enhanced by G6P or Pi addition. Rapid G6P or Pi influx was registered by light-scattering in microsomes not containing G6P or Pi. The G6PT inhibitor, S3483, blocked G6P transport irrespectively of experimental conditions. We conclude that hepatic G6PT functions as an uniporter.
authors: Department of Pathophysiology, Experimental Medicine and Public Health, University of Siena, Siena, Italy.
authors: Paola
authors: P
authors: Marcolongo
authors: Rosella
authors: R
authors: Fulceri
authors: Roberta
authors: R
authors: Giunti
authors: Eva
authors: E
authors: Margittai
authors: Gabor
authors: G
authors: Banhegyi
authors: Angelo
authors: A
authors: Benedetti
mesh_terms: D000818:Animals; D017920:Antiporters / Q000378:metabolism*; D001693:Biological Transport, Active; D019298:Glucose-6-Phosphate / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008027:Light; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D010539:Permeability; D010710:Phosphates / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012542:Scattering, Radiation
chemical_list: D017920:Antiporters; D009004:Monosaccharide Transport Proteins; D010710:Phosphates; C111261:glucose 6-phosphate(transporter); D019298:Glucose-6-Phosphate