We have developed a new heterologous expression system for mammalian glucose transporters. The system is based on a Saccharomyces cerevisiae strain completely deleted for all its endogenous hexose transporters and unable to take up and to grow on hexoses. To target the heterologous glucose transporters into the yeast plasma membrane in a fully active form, additional mutations had to be introduced into the hexose transport-deficient strain. Although GLUT1 was localized at the cell surface already in the parent strain, it supported uptake of glucose only in an Δhxt fgy1-1 mutant strain. Moreover, various mutations within the first half of the second predicted transmembrane helix converted GLUT1 into a form able to support uptake of glucose into yeast cells. GLUT4 was trapped in intracellular structures but became functionally expressed in the plasma membrane in Δhxt fgy1-1 fgy4X mutant strains. Glucose transport kinetics were determined with intact yeast cells by zero-trans influx measurements with a Km of 3.2 mM for human GLUT1 and of 12.6 mM for human GLUT4. Cytochalasin B inhibited these activities. Growth tests revealed that both transporter proteins are able to mediate uptake of glucose, mannose and galactose, but not of fructose. The new heterologous expression system should be a valuable tool to develop cell based high-throughput screening assays for identifying pharmaceutical compounds influencing the transporters.

This content is only available via PDF.
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.