TRPγ, a Drosophila TRP-related subunit, forms a regulated cation channel with TRPL

TRP and TRPL are two light-sensitive cation channel subunits required for the Drosophila photoresponse; however, our understanding of the identities, subunit composition, and function of the light-responsive channels is incomplete. To explain the residual photoresponse that remains in the trp mutant, a third TRP-related subunit has previously been proposed to function with TRPL. Here, we identify such a subunit, TRP gamma. We show that TRP gamma is highly enriched in photoreceptor cells and preferentially heteromultimerizes with TRPL in vitro and in vivo. The N-terminal domain of TRP gamma dominantly suppressed the TRPL-dependent photoresponse, indicating that TRP gamma-TRPL heteromultimers contribute to the photoresponse. While TRPL and TRP gamma homomultimers are constitutively active, we demonstrate that TRPL-TRP gamma heteromultimers form a regulated phospholipase C- (PLC-) stimulated channel.