Saccharomyces cerevisiae cells express three defined potassium-specific transport systems en-coded by TRK1, TRK2 and TOK1. To gain a more complete understanding of the physiological function of these transport proteins, we have constructed a set of isogenic yeast strains carrying all combinations of trk1delta, trk2delta and tok1delta null mutations. The in vivo K+ transport characteristics of each strain have been documented using growth-based assays, and the in vitro biochemical and electrophysiological properties associated with K+ transport have been determined. As has been reported previously, Trk1p and Trk2p facilitate high-affinity potassium uptake and appear to be functionally redundant under a wide range of environmental conditions. In the absence of TRK1 and TRK2, strains lack the ability specifically to take up K+, and trk1deltatrk2delta double mutant cells depend upon poorly understood non-specific cation uptake mechanisms for growth. Under conditions that impair the activity of the non-specific uptake system, termed NSC1, we have found that the presence of functional Tok1p renders cells sensitive to Cs+. Based on this finding, we have established a growth-based assay that monitors the in vivo activity of Tok1p.
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| Gene | Phenotype | Experiment Type | Mutant Information | Strain Background | Chemical | Details |
|---|---|---|---|---|---|---|
| TRK1 | acid pH resistance: decreased | classical genetics | null Allele: trk1-Δ | Other | phosphoric acid | Treatment: SDAP medium plus 100 mM KCl, at low pH, pH 3.1 |
| TRK2 | acid pH resistance: normal | classical genetics | null Allele: trk2-Δ | Other | phosphoric acid | Treatment: SDAP medium plus 100 mM KCl, at low pH, pH 3.1 |
| TOK1 | acid pH resistance: normal | classical genetics | null Allele: tok1-Δ | Other | phosphoric acid | Treatment: SDAP medium plus 100 mM KCl, at low pH, pH 3.1 |
| TRK1 | small molecule transport: decreased | classical genetics | null Allele: trk1-Δ | Other | rubidium(1+) | Media: potassium starvation Details: decreased rubidium influx |
| TRK1 | small molecule transport: decreased | classical genetics | null Allele: trk1-Δ | Other | potassium(1+) | Details: decreased potassium efflux |
| TRK2 | small molecule transport: normal | classical genetics | null Allele: trk2-Δ | Other | rubidium(1+) | Media: potassium starvation Details: normal rubidium influx |
| TRK2 | small molecule transport: normal | classical genetics | null Allele: trk2-Δ | Other | potassium(1+) | Details: normal potassium efflux |
| TOK1 | small molecule transport: normal | classical genetics | null Allele: tok1-Δ | Other | rubidium(1+) | Media: potassium starvation Details: normal rubidium influx |
| TOK1 | small molecule transport: normal | classical genetics | null Allele: tok1-Δ | Other | potassium(1+) | Details: potassium efflux |
| TRK2 | vegetative growth: absent | classical genetics | null Allele: trk2-Δ | Other | 100 mM caesium chloride | Treatment: SDAP agar (pH 4.1) supplemented with KCl, 100 mM |
Increase the total number of rows showing on this page by using the pull-down located below the table, or use the page scroll at the table's top right to browse through the table's pages; use the arrows to the right of a column header to sort by that column; filter the table using the "Filter" box at the top of the table; click on the small "i" buttons located within a cell for an annotation to view further details about experiment type and any other genes involved in the interaction.
| Evidence ID | Analyze ID | Interactor | Interactor Systematic Name | Interactor | Interactor Systematic Name | Allele | Assay | Annotation | Action | Phenotype | SGA score | P-value | Source | Reference | Note |
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Increase the total number of rows showing on this page by using the pull-down located below the table, or use the page scroll at the table's top right to browse through the table's pages; use the arrows to the right of a column header to sort by that column; filter the table using the "Filter" box at the top of the table; click on the small "i" buttons located within a cell for an annotation to view further details about experiment type and any other genes involved in the interaction.