Functional expression of the pore forming subunit of the ATP-sensitive potassium channel in Saccharomyces cerevisiae

We have expressed the pore-forming subunits (Kir 6.1 and Kir 6.2) of the ma mmalian ATP-sensitive potassium channel in a potassium-transport deficient yeast strain (trk1 trk2). Functional expression of Kir 6.2 and Kir 6.1 can, complement growth deficiency weakly and strongly respectively of the yeast strain on low-potassium medium. Mutations of Kir 6.2 that abolish ATP sens itivity (K185Q, I182Q) and enhance trafficking to the plasma membrane surfa ce (Kir 6.2 Delta C36) lead to significantly better growth rescue. Growth r escue of Kir 6.1, Kir 6.2 and the above mutants can be inhibited by pharmac ological agents (cesium ions, phentolamine and quinine) known to decrease c hannel activity by direct interaction with the pore forming subunit. Thus w e have developed a system in yeast that can report both loss and gain of fu nction mutations in these subunits and pharmacological interventions. (C) 2 000 Academic Press.