G-protein gamma subunit 1 is required for sugar reception in Drosophila

Though G-proteins have been implicated in the primary step of taste signal transduction, no direct demonstration has been done in insects. We show here that a G-protein gamma subunit, G gamma 1, is required for the signal transduction of sugar taste reception in Drosophila. The G gamma 1 gene is expressed mainly in one of the gustatory receptor neurons. Behavioral responses of the flies to sucrose were reduced by the targeted suppression of neural functions of G gamma 1-expressing cells using neural modulator genes such as the modified Shaker K+ channel (EKO), the tetanus toxin light chain or the shibire (shi(ts1)) gene. RNA interference targeting to the G gamma 1 gene reduced the amount of G gamma 1 mRNA and suppressed electrophysiological response of the sugar receptor neuron. We also demonstrated that responses to sugars were lowered in G gamma 1 null mutant, G gamma 1(N159). These results are consistent with the hypothesis that G gamma 1 participates in the signal transduction of sugar taste reception.