Acts as guanine nucleotide exchange factor (GEF) for Rho GTPase. Has a critical roles in the generation of rhythmic behaviors: feeding, defecation and ovulation by dynamically regulating the concentration of intracellular calcium. Plays a role in male tail tip morphogenesis (PubMed:21408209). Strong expression in the pharynx, proximal gonad, spermatheca, intestine and rectal epithelia. An acidic domain (AC) contains three highly conserved tyrosines that are involved in the autoinhibition of GEF activity. GEF activity is regulated by phosphorylation on tyrosine residues. RNAi-mediated knockdown results in male tail tip defects. Nematode tempo - Issue 71 of June 2006