Analysis of the localization of STE6/CFTR chimeras in a Saccharomyces cerevisiae model for the cystic fibrosis defect CFTRΔF508

Chris Paddon, Diego Loayza, Luca Vangelista, Roberto Solari, Susan Michaelis

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21 Scopus citations


The use of yeast as a model system to study mammalian proteins is attractive, because yeast genetic tools can be utilized if a suitable phenotype is created, STE6, the Saccharomyces cerevisiae a-factor mating pheromone transporter, and CFTR, the mammalian cystic fibrosis transmembrane conductance regulator, are both members of the ATP binding cassette (ABC) superfamily. Teem et al, (1993) described a yeast model for studying a mutant form of the cystic fibrosis protein, CFTRΔF508. The model involved expression of a chimeric molecule in which a portion of yeast STE6 was replaced with the corresponding region from mammalian CFTR. The STE6/CFTR chimera complemented a ste6 mutant strain for mating, indicating that it could export a-factor. However, mating efficiency was dramatically reduced upon introduction of ΔF508, providing a yeast phenotype for this mutation. In human cells, the ΔF508 mutation results in retention of CFTR in the endoplasmic reticulum (ER), and possibly in reduction of its chloride-channel activity. Here we examine the basis for the differences in STE6 activity promoted by the wild-type and mutant STE6/CFTR chimeras, By analysis of protein stability and subcellular localization, we find that the mutant chimera is not ER-retained in yeast. We conclude that the molecular basis for the reduced mating of the STE6/CFTRΔF508 chimera must reflect a reduction in its capacity to transport a-factor, rather than mistrafficking. Thus, STE6/CFTRΔF508 in yeast appears to be a good genetic model to probe certain aspects of protein function, but not to study protein localization.

Original languageEnglish (US)
Pages (from-to)1007-1017
Number of pages11
JournalMolecular Microbiology
Issue number5
StatePublished - 1996

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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