Many proteins including ion channels mediate a variety of biological activities of cells through forming large molecular assemblies via protein-protein interactions. Hence, to understand the function of a particular protein, it is often useful to identify other proteins with which it associates. The two-hybrid system is a widely used yeast-based genetic approach for detecting protein-protein interactions and provides a powerful way of isolating ion channel-associated proteins in an in vivo setting without purifying both proteins. This system is thought to be one of the important techniques for "Proteome" analysis in the post-genomic era. In this article, we describe the yeast two-hybrid assay we have used to identify proteins binding to asic-sensing ion channel ASIC3 and urate transporter 1 (URAT1) and discuss some general and specific considerations about using ion channel proteins in the two-hybrid system.