Receptor for inositol 1,4,5-trisphosphate, a second messenger that regulates intracellular calcium homeostasis. Binds in vitro to both inositol 1,4,5-trisphosphate (1,4,5-InsP3) and inositol 2,4,5-trisphosphate (2,4,5-InsP3) with high affinity and does not discriminate between the phosphate at 1 or 2 position. Can also bind inositol 1,3,4,5-tetrakisphosphate (1,3,4,5-InsP4) and inositol 4,5-bisphosphate (4,5-InsP2), but with lower affinity. Acts as a timekeeper/rhythm generator via calcium signaling, affecting the defecation cycle and pharyngeal pumping. Affects normal hermaphrodite and male fertility as a participant in intracellular signaling by acting downstream of let-23/lin-3 which regulates ovulation, spermathecal valve dilation and male mating behavior. Important for early embryonic development; controls epidermal cell migration and may also regulate filopodial protrusive activity during epithelial morphogenesis. Component of inositol trisphosphate (IP3)-mediated downstream signaling pathways that controls amphid sensory neuronal (ASH)-mediated response to nose touch and benzaldehyde but not other ASH-mediated responses.
