Mediates the production of the second messenger molecules diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3) which plays an important role in the regulation of intracellular signaling cascades (Probable). Regulates basal and ovulatory sheath cell contractions by controlling Ca(2+) oscillations via IP3-mediated activation of IP3 receptor itr-1 (PubMed:15194811). In intestinal epithelial cells, regulates Ca(2+) oscillations which control posterior body wall muscle contractions required for defecation by IP3-mediated activation of itr-1 and probably by activating TRPM channels gon-2 and gtl-1 by reducing PIP2 levels (PubMed:19923421, PubMed:16186564). By activating tpa-1 via DAG production, required for the expression of antimicrobial peptide nlp-29 in the epidermis in response to fungal infection or physical injury (PubMed:19380113). By triggering Ca(2+) transient via IP3-mediated activation of IPR3 receptor itr-1 in ASH sensory neurons, involved in avoidance behavior in response to nose touch (PubMed:19730689). Probably by regulating neuronal transmission in ALA neurons, mediates the decrease in pharyngeal pumping and locomotion during the quiescent state that precedes each larval molt, downstream of lin-3 and receptor let-23 and upstream of tpa-1 but not itr-1 (PubMed:17891142). During embryogenesis, may play an role in epidermal morphogenesis together with plc-1 (PubMed:18369461). Probably downstream of receptor daf-2, regulates male-sex muscle excitability in the absence of food (PubMed:18604269). a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol-4,5-bisphosphate) + H2O = 1D-myo-inositol 1,4,5-trisphosphate + a 1,2-diacyl-sn-glycerol + H(+) Expressed in intestine, isthmus of the pharynx, proximal gonad sheath cells, spermatheca and uterine sheath cells (PubMed:15194811, PubMed:16186564). In males, expressed in the valve cell, the vas deferens and retractor and ventral protactor muscles (PubMed:15958491, PubMed:18604269). RNAi-mediated knockdown causes sterility resulting from impaired spermatheca dilatation causing a defect in ovulation, and a severe decrease in sheath cell basal and peak ovulatory contractions (PubMed:15194811, PubMed:18369461). The few embryos laid are arrested at the embryonic stage (PubMed:18369461). Cycles of posterior body wall muscle contractions are prolonged and arrhythmic resulting in a defecation defect (PubMed:16186564). Ca(2+) oscillations in intestinal cells are arrhythmic and the whole cell current amplitude is severely reduced (PubMed:16186564, PubMed:19923421). RNAi-mediated knockdown in males causes an increase in spontaneous muscle seizures in the absence of food in an unc-103 mutant background (PubMed:18604269). Ca(2+) transient increase and avoidance behavior are defective in response to nose touch but not to benzaldehyde (PubMed:19730689). nlp-29 expression is abrogated following fungal infection by D.coniospora and severely reduced following physical injury (PubMed:19380113).