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Abstract
The efflux of Ca2+ from the yeast Saccharomyces cerevisiae is induced by the influx of mono- or divalent cations. The mechanism of the tight coupling between K+ influx and Ca2+ efflux was investigated. Two possibilities were examined: (1) Ca2+ efflux is induced only by the carriermediated and energy-dependent K+ uptake or (2) Ca2+ efflux can be induced by electric coupling to K+ influx which is driven by its inward electrochemical gradient in the presence of K+ ionophores. It was found that K+ influx in the presence of valinomycin or nigericin and in the absence of glucose did not induce Ca2+ efflux. It is suggested, therefore, that the coupling is mediated by antiport carriers which exchange Ca2+ and K+.
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© Society for General Microbiology 1982