THE DROSOPHILA CATION CHANNEL TRPL EXPRESSED IN INSECT SF9 CELLS IS STIMULATED BY AGONISTS OF G-PROTEIN-COUPLED RECEPTORS

Structures and regulations of vertebrate channels responsible for sust ained calcium elevations after hormone stimulation are largely unknown . Therefore, the Drosophila photoreceptor channels, trp and trpl, whic h are assumed to be involved in calcium influx, serve as model system. trpl expressed in Sf9 cells showed spontanous activity. Hormonal stim ulations of calcium influx (detected by fura-2) and of an outwardly re ctifying current were observed in Sf9 cells coinfected with baculoviru ses encoding trpl and various heptahelical receptors for histamine, th rombin, and thromboxane A(2), all known to cause phospholipase C-beta activation in mammalian cells. Although the identity of the G-proteins and of possible second messengers involved need to be clarified, it i s clear that trpl represents a receptor/G-protein regulated cation cha nnel.