Regulation and interconversion of the potassium transport systems of Saccharomyces cerevisiae as revealed by rubidium transport

Abstract

The kinetics of Rb+ transport in Saccharomyces cerevisiae depended on the K+ content of the cells and on K+ starvation, as follows. 1. In cells with normal K+ (grown at millimolar K+), Rb+ transport was regulated by internal K+. The loss of K+ first decreased the Km and later increased the Vmax of Rb+ transport. 2. K+ starvation of normal‐K+ cells for 4–5 h decreased the Km of Rb+ transport below the minimum observed after K+ loss. During this time Eadie‐Hofstee plots of Rb+ transport suggest that the existing system was converted into a new one with a higher affinity. 3. Growth at 10 μM K+ only required the system triggered by K+ loss, and the system expressed in K+‐starved cells was not expressed under these conditions. Copyright © 1986, Wiley Blackwell. All rights reserved