such as Kir family channels to complement the growth of K + uptakedeficient Saccharomyces cerevisiae strain, e.g., SGY1528 thatlacks K + uptake transporters Trk1 and Trk2 [12], in low K + media has proven particularly useful for identification of novel trafficking pathways of membrane proteins. For instance, Shikano et al. used SGY1528 cells to screen library of Kir2.1 channels that are fused with C-terminal random 8-mer peptide sequences and identified a group of cis-acting sequences that specifically interact with 14-3-3 proteins and promote surface expression of membrane proteins [13]. Moreover, the screening of a cDNA library transduced into the Kir2.1 channel-expressing SGY1528 cells resulted in a discovery of a trans-acting protein that enhances the cell surface expression of Kir2.1 [14]. The SGY1528 has been also successfully used to identify the structural determinants for the K + selectivity of G-protein gated inwardly-rectifying K + channel