CATION TRANSPORT IN YEAST

Abstract

The uptake of K by K-deficient cells of bakers'' yeast was studied. From kinetic data it is concluded that azide inhibits K transport in yeast, not by reacting with cytochrome oxidase in the mitochondria, but by combining with a carrier in the cell wall. The maximum concentration of this carrier calculated from determinations of bound azide was 0.1 [mu]M/g cells. In the presence of PO4 and fermentable substrates, K is transported by an azide-insensitive mechanism, additive to the action of the azide-sensitive carrier. Present experiments do not support the contention that a separate Na carrier is responsible for Na movement in yeast.