Efficient export of the glucose transporter Hxt1p from the endoplasmic reticulum requires Gsf2p

Efficient export of the glucose transporter Hxt1p from the endoplasmic reticulum requires Gsf2p

Peter W. Sherwood and
Marian Carlson*

Department of Genetics and Development, Columbia University, New York, NY 10032

Edited by Gottfried Schatz, University of Basel, Basel, Switzerland, and approved May 3, 1999 (received for review November 2, 1998)

Abstract

Mutations in the GSF2 gene cause glucose starvation phenotypes in Saccharomyces cerevisiae. We have isolated the HXT1 gene, which encodes a low-affinity, high-capacity glucose transporter, as a multicopy suppressor of a gsf2 mutation. We show that gsf2 mutants accumulate Hxt1p in the endoplasmic reticulum (ER) and that Gsf2p is a 46-kDa integral membrane protein localized to the ER. gsf2 mutants also display a galactose growth defect and abnormal localization of the galactose transporter Gal2p but are not defective in function or localization of the high-affinity glucose transporter Hxt2p. These findings suggest that Gsf2p functions in the ER to promote the secretion of certain hexose transporters.

Footnotes

↵ * To whom reprint requests should be addressed. e-mail: mbc1{at}columbia.edu.
This paper was submitted directly (Track II) to the Proceedings Office.
ABBREVIATIONS:

ER,

endoplasmic reticulum;

5-FOA,

5-fluoroorotic acid;

GFP,

green fluorescent protein;

HA,

hemagglutinin;

SC,

synthetic complete