1.A.69.3.9
Gustatory receptor Gr66a of 527 aas and 8 TMSs, specific for bitter compounds (Thorne et al. 2004). Gr66a cells respond to bitter compounds such as caffeine, theophylline, threonine or valine. Flies avoid bitter substances, suggesting that Gr66a neuron activity is sufficient to mediate avoidance behavior. This receptor is required for sensing and avoiding N,N-Diethyl-meta-toluamide (DEET), the most widely used insect repellent worldwide, as well as L-canavanine, a plant-derived insecticide. Gr66a neurons are also involved in the sex-specific perception of molecules inducing male avoidance behavior, probably through sensing 7-tricosene (7-T), a male cuticular pheromone and leading to inhibition of male-male courtship.