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The glucose‐6‐phosphate transport is not mediated by a glucose‐6‐phosphate/phosphate exchange in liver microsomes
Author(s) -
Marcolongo Paola,
Fulceri Rosella,
Giunti Roberta,
Margittai Eva,
Banhegyi Gabor,
Benedetti Angelo
Publication year - 2012
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2012.07.018
Subject(s) - microsome , phosphate , glucose 6 phosphate , antiporter , biochemistry , transporter , chemistry , pi , glucose transporter , liposome , membrane transport , vesicle , enzyme , biology , membrane , insulin , endocrinology , gene
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.