The missing Gαq effector pathway and targeted forward genetic screens for finding it. (A) Summary of the Gαo and Gαq pathways that drive C. elegans locomotion and egg laying. Solid lines indicate that direct interactions are known or likely, while dashed lines, such as the missing Gαq effector pathway, indicate probable missing components. The green proteins positively drive locomotion and neurotransmitter release, and reducing their function causes decreased neurotransmitter release, decreased locomotion or paralysis, and decreased egg laying. The red proteins inhibit locomotion and neurotransmitter release, and reducing their function causes increased neurotransmitter release and hyperactive behaviors. Note that the GOA-1 (Gαo) pathway exerts its inhibitory effects in a Gαq pathway-dependent manner. Not shown is a third Gα pathway in this network (Gαs) (; ; , ). The model is based on the following studies: , , , , , , , ), , , ), , , , and . (B) Two forward genetic screen strategies for identifying the missing Gαq effector pathway. Both screen strategies use the mutagen ENU to suppress the slow growth and hyperactive phenotypes of mutants with an overactive Gαq pathway for the purpose of identifying downstream effectors.