[31] Transport in isolated yeast vacuoles: Characterization of arginine permease

This chapter describes a method for studying transport in intact isolated yeast vacuoles and its application to characterize an arginine permease present in the tonoplast. It also describes that the intact isolated yeast vacuoles are excellent models for studying intracellular transport. Just as isolated tonoplast vesicles, isolated vacuoles offer the opportunity of measuring solute fluxes across the tonoplast directly. Yet, they are isolated without osmotic shock, retain their solutes, and reflect the natural state of the vacuole more closely than vacuolar membrane vesicles. The potential of isolated vacuoles for transport studies has not yet been fully exploited. It will be interesting to explore active, Adenosine triphosphate (ATP) driven transport in intact vacuoles and to compare it with the transport properties in vacuolar membrane vesicles. The lack of internal pools is a big advantage because it reduces or eliminates the possible contribution of passive exchange transport systems to the observed transport rates.