Plays a central role in social feeding behavior and oxygen sensation by synthesizing 3',5'-cyclic guanosine monophosphate (cGMP) from GTP. Oxygen, which binds to its heme-binding sites, probably regulates social behavior by modulating its activity. cGMP is a common second messenger in sensory transduction and is implicated in oxygen sensation. Indeed, C.elegans exhibits a strong behavioral preference for 5-12% oxygen, avoiding higher and lower oxygen levels; a higher level of oxygen inducing a naturally polymorphic social feeding behavior. Involved in avoidance of hyperoxia and for oxygen-induced aggregation and bordering, probably by mediating oxygen-sensing in URX, AQR and PQR sensory neurons