COASSEMBLY OF TRP AND TRPL PRODUCES A DISTINCT STORE-OPERATED CONDUCTANCE

The Drosophila retinal-specific protein, TRP (transient receptor poten tial), is the founding member of a family of store-operated channels ( SOCs) conserved from C. elegans to humans. In vitro studies indicate t hat TRP is a SOC, but that the related retinal protein, TRPL, is const itutively active. In the current work, we report that coexpression of TRP and TRPL leads to a store-operated, outwardly rectifying current d istinct from that owing to either TRP or TRPL alone. TRP and TRPL inte ract directly, indicating that the TRP-TRPL-dependent current is media ted by heteromultimeric association between the two subunits. We propo se that the light-activated current in photoreceptor cells is produced by a combination of TRP homo- and TRP-TRPL heteromultimers.