RIC-8 (synembryn): A novel conserved protein that is required for G(q)alpha signaling in the C-elegans nervous system

Recent studies describe a network of signaling proteins centered around G(o )alpha and G(q)alpha that regulates neurotransmitter secretion in C. elegan s by controlling the production and consumption of diacylglycerol (DAG). We sought other components of the G(o)alpha-G(o)alpha signaling network by sc reening for aldicarb-resistant mutants with phenotypes similar to egl-30 (G (o)alpha) mutants. In so doing, we identified ric-8, which encodes a novel protein named RIC-8 (synembryn). Through cDNA analysis, we show that RIC-8 is conserved in vertebrates. Through immunostaining, we show that RIC-8 is concentrated in the cytoplasm of neurons. Exogenous application of phorbol esters or loss of DGK-1 (diacylglycerol kinase) rescues ric-8 mutant phenot ypes. A genetic analysis suggests that RIC-8 functions upstream of, or in c onjunction with, EGL-30 (G(o)alpha).