Guanine nucleotide-binding proteins (G proteins) are involved as modulators or transducers in various transmembrane signaling systems. Mediates the transduction of food and serotonin signals, which modulates the avoidance response to the odorant octanol. Has a role in lifespan to promote longevity. G proteins are composed of 3 units; alpha, beta and gamma. The alpha chain contains the guanine nucleotide binding site. Expressed in ADL and ASH neurons. Slow to respond to octanol. Belongs to the G-alpha family.