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Differential sorting of two glucose transporters expressed in insulin-sensitive cells
Journal article   Peer reviewed

Differential sorting of two glucose transporters expressed in insulin-sensitive cells

Robert C Piper, Lisa J Hess and David E James
The American journal of physiology, Vol.260(3 Pt 1), pp.C570-580
03/1991
DOI: 10.1152/ajpcell.1991.260.3.c570
PMID: 2003579

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Abstract

The insulin-regulatable glucose transporter (IRGT) is specifically expressed in muscle and fat cells and undergoes translocation from an intracellular compartment to the cell surface following acute insulin treatment. This study examined sorting differences between the IRGT and the homologous HepG2/erythrocyte/brain glucose transporter (HepG2 GT) when expressed together in insulin-responsive 3T3-L1 adipocytes. The ratio of the amount of transporter per unit protein in the plasma membrane fraction vs. the intracellular membrane fraction was 1:2 for the HepG2 GT and 1:30 for the IRGT. Insulin treatment increased the plasma membrane concentration of the IRGT by 10-fold and the HepG2 GT by 3.5-fold. This distribution was confirmed by confocal immunofluorescence microscopy. Differential sorting within intracellular organelles was evident by sucrose gradient analysis and immunoisolation of transporter vesicles and by double immunofluorescence labeling. We propose that differential sorting at an intracellular locus preferably withdraws the IRGT from a pathway which is in close communication with the plasma membrane, thus allowing the IRGT to regulate glucose entry into fat and muscle cells in a highly insulin-regulated fashion.
Adipose Tissue - metabolism Animals Biological Transport, Active Cell Fractionation Cell Line Cell Membrane - metabolism Centrifugation, Density Gradient Deoxyglucose - metabolism Fibroblasts - metabolism Insulin - pharmacology Kinetics Mice Monosaccharide Transport Proteins - isolation & purification Monosaccharide Transport Proteins - metabolism Subcellular Fractions - metabolism

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