TRK2 is not a low-affinity potassium transporter in Saccharomyces cerevisiae.
TRK1 and TRK2 encode proteins involved in K+ uptake in Saccharomyces cerevisiae. A kinetic study of Rb+ influx in trk1 TRK2, trk1 TRK2D, and trk1 trk2 mutants reveals that TRK2 shows moderate affinity for Rb+. K(+)-starved trk1 delta TRK2 cells show a low-affinity component accounting for almost the total Vmax ... of the influx and a moderate-affinity component exhibiting a very low Vmax. Overexpression of TRK2 in trk1 delta TRK2D cells increases the Vmax of the moderate-affinity component, and this component disappears in trk1 delta trk2 delta cells. In contrast, the low-affinity component of Rb+ influx in trk1 delta TRK2 cells is not affected by mutations in TRK2. Consistent with the different levels of activity of the moderate-affinity Rb+ influx, trk1 delta TRK2 cells grow slowly in micromolar K+, trk1 delta TRK2D cells grow rapidly, and trk1 delta trk2 delta cells fail to grow. The existence of a unique K+ uptake system composed of several proteins is also discussed.
Mesh Terms:
Azides, Biological Transport, Carrier Proteins, Cation Transport Proteins, Fungal Proteins, Membrane Proteins, Potassium, Recombinant Proteins, Rubidium, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins
Azides, Biological Transport, Carrier Proteins, Cation Transport Proteins, Fungal Proteins, Membrane Proteins, Potassium, Recombinant Proteins, Rubidium, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins
J. Bacteriol.
Date: Jan. 01, 1994
PubMed ID: 8282703
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