A regulatory domain in the C-terminal extension of the yeast glycerol channel Fps1p

Kristina Hedfalk*, Roslyn M. Bill, Jonathan G.L. Mullins, Sara Karlgren, Caroline Filipsson, Johanna Bergstrom, Markus J. Tamás, Jan Rydström, Stefan Hohmann

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The Saccharomyces cerevisiae gene FPS1 encodes an aquaglyceroporin of the major intrinsic protein (MIP) family. The main function of Fps1p seems to be the efflux of glycerol in the adaptation of the yeast cell to lower external osmolarity. Fps1p is an atypical member of the family, because the protein is much larger (669 amino acids) than most MIPs due to long hydrophilic extensions in both termini. We have shown previously that a short domain in the N-terminal extension of the protein is required for restricting glycerol transport through the channel (Tamás, M. J., Karlgren, S., Bill, R. M., Hedfalk, K., Allegri, L., Ferreira, M., Thevelein, J. M., Rydström, J., Mullins, J. G. L., and Hohmann, S. (2003) J. Biol. Chem. 278, 6337-6345). Deletion of the N-terminal domain results in an unregulated channel, loss of glycerol, and osmosensitivity. In this work we have investigated the role of the Fps1p C terminus (139 amino acids). A set of eight truncations has been constructed and tested in vivo in a yeast fps1Δ strain. We have performed growth tests, membrane localization following cell fractionation, and glycerol accumulation measurements as well as an investigation of the osmotic stress response. Our results show that the C-terminal extension is also involved in restricting transport through Fps1p. We have identified a sequence of 12 amino acids, residues 535-546, close to the sixth transmembrane domain. This element seems to be important for controlling Fps1p function. Similar to the N-terminal domain, the C-terminal domain is amphiphilic and has a potential to dip into the membrane.

Original languageEnglish
Pages (from-to)14954-14960
Number of pages7
JournalJournal of Biological Chemistry
Issue number15
Publication statusPublished - 9 Apr 2004

Bibliographical note

© 2004 by The American Society for Biochemistry and Molecular Biology, Inc. Publisher's version/PDF may be used after a 12 months embargo period


  • saccharomyces cerevisiae gene
  • FPS1
  • aquaglyceroporin
  • major intrinsic protein family
  • Fps1p
  • yeast cell
  • external osmolarity
  • N-terminal extension
  • glycerol transport
  • N-terminal domain
  • Fps1p C terminu
  • yeast fps1Δ strain


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