A short regulatory domain restricts glycerol transport through yeast Fps1p

Markus J. Tamás, Sara Karlgren, Roslyn M. Bill, Kristina Hedfalk, Laura Allegri, Marie Ferreira, Johan M. Thevelein, Jan Rydström, Jonathan G.L. Mullins, Stefan Hohmann*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The controlled export of solutes is crucial for cellular adaptation to hypotonic conditions. In the yeast Saccharomyces cerevisiae glycerol export is mediated by Fpslp, a member of the major intrinsic protein (MIP) family ]of channel proteins. Here we describe a short regulatory domain that restricts glycerol transport through Fpslp. This domain is required for retention of cellular glycerol under hypertonic stress and hence acquisition of osmotolerance. It is located in the N-terminal cytoplasmic extension close to the first transmembrane domain. Several residues within that domain and its precise position are critical for channel control while the proximal residues 13-215 of the N-terminal extension are not required. The sequence of the regulatory domain and its position are perfectly conserved in orthologs from other yeast species. The regulatory domain has an amphiphilic character, and structural predictions indicate that it could fold back into the membrane bilayer. Remarkably, this domain has structural similarity to the channel forming loops B and E of Fpslp and other glycerol facilitators. Intragenic second-site suppressor mutations of the sensitivity to high osmolarity conferred by truncation of the regulatory domain caused diminished glycerol transport, confirming that elevated channel activity is the cause of the osmosensitive phenotype.

Original languageEnglish
Pages (from-to)6337-6345
Number of pages9
JournalJournal of Biological Chemistry
Issue number8
Early online date16 Dec 2002
Publication statusPublished - 21 Feb 2003

Bibliographical note

© 2003 by The American Society for Biochemistry and Molecular Biology, Inc.


  • amino acid sequence
  • base sequence
  • biological transport
  • DNA Primers
  • glycerol
  • kinetics
  • kluyveromyces
  • membrane proteins
  • models, molecular
  • mutagenesis
  • Mutagenesis, Site-Directed
  • protein structure, secondary
  • recombinant proteins
  • saccharomyces cerevisiae
  • saccharomyces cerevisiae Proteins
  • sequence alignment
  • sequence deletion
  • sequence homology, amino acid


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