The glucose-6-phosphate transport is not mediated by a glucose-6-phosphate/phosphate exchange in liver microsomes

FEBS Lett. 2012 Sep 21;586(19):3354-9. doi: 10.1016/j.febslet.2012.07.018. Epub 2012 Jul 20.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antiporters / metabolism*
  • Biological Transport, Active
  • Glucose-6-Phosphate / metabolism*
  • In Vitro Techniques
  • Kinetics
  • Light
  • Male
  • Microsomes, Liver / metabolism*
  • Monosaccharide Transport Proteins / metabolism*
  • Permeability
  • Phosphates / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Scattering, Radiation

Substances

  • Antiporters
  • Monosaccharide Transport Proteins
  • Phosphates
  • glucose 6-phosphate(transporter)
  • Glucose-6-Phosphate