The Drosophila TRP channel has served as a genetic model for understanding the functions, modes of activation, subunit assembly and protein interactions of TRP proteins in an in vivo context. During the last few years, it has become clear that TRP associates with a macromolecular complex, the signalplex, which includes TRP and many other signalling proteins critical for phototransduction. The central protein in this assembly is the PDZ protein INAD. Association of target proteins with INAD is required for rapid termination of the photoresponse and for proper localization of signalling proteins, such as TRP. In addition, TRP is reciprocally required for localizing INAD, indicating that TRP functions as both an ion channel and a molecular anchor. The TRP superfamily is comprised of six subfamilies, each of which includes homologues in Drosophila. Due to the similarities between mammalian and Drosophila TRP channels, and the tractability of genetic approaches in the fruitfly, investigations are underway to characterize the roles of additional Drosophila TRP proteins. Thus, the fruitfly continues to provide a valuable in vivo model to characterize the functions, interacting partners and activation mechanisms of TRP-related proteins.