Fps1p controls the accumulation and release of the compatible solute glycerol in yeast osmoregulation.
Artikel i vetenskaplig tidskrift, 1999

The accumulation of compatible solutes, such as glycerol, in the yeast Saccharomyces cerevisiae, is a ubiquitous mechanism in cellular osmoregulation. Here, we demonstrate that yeast cells control glycerol accumulation in part via a regulated, Fps1p-mediated export of glycerol. Fps1p is a member of the MIP family of channel proteins most closely related to the bacterial glycerol facilitators. The protein is localized in the plasma membrane. The physiological role of Fps1p appears to be glycerol export rather than uptake. Fps1 delta mutants are sensitive to hypo-osmotic shock, demonstrating that osmolyte export is required for recovery from a sudden drop in external osmolarity. In wild-type cells, the glycerol transport rate is decreased by hyperosmotic shock and increased by hypo-osmotic shock on a subminute time scale. This regulation seems to be independent of the known yeast osmosensing HOG and PKC signalling pathways. Mutants lacking the unique hydrophilic N-terminal domain of Fps1p, or certain parts thereof, fail to reduce the glycerol transport rate after a hyperosmotic shock. Yeast cells carrying these constructs constitutively release glycerol and show a dominant hyperosmosensitivity, but compensate for glycerol loss after prolonged incubation by glycerol overproduction. Fps1p may be an example of a more widespread class of regulators of osmoadaptation, which control the cellular content and release of compatible solutes.

Water-Electrolyte Balance

Gene Deletion



Osmolar Concentration


Signal Transduction

Saccharomyces cerevisiae Proteins


Fungal Proteins

Membrane Proteins


Gene Expression Regulation


Hypertonic Solutions

growth & development

Saccharomyces cerevisiae




Biological Transport



Markus J. Tamás

Göteborgs universitet

K Luyten

F C Sutherland

A Hernandez

J Albertyn

H Valadi

Göteborgs universitet

H Li

B A Prior

S G Kilian

J Ramos

L Gustafsson

Göteborgs universitet

J M Thevelein

Stefan Hohmann

Göteborgs universitet

Molecular Microbiology

0950-382X (ISSN) 1365-2958 (eISSN)

Vol. 31 4 1087-104


Biokemi och molekylärbiologi



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