Plays a role as NO/PRKG1-dependent regulator of IP3-induced calcium release; its phosphorylation by PRKG1 inhibits bradykinin and IP3-induced calcium release from intracellular stores. Recruits PRKG1 to the endoplasmic reticulum and may mediate the assembly of PRKG1 and ITPR1 in a macrocomplex. Involved in PRKG1 signaling cascade leading to inhibition of platelet activation and aggregation. Mediates also NO-dependent inhibition of calcium signaling in gastrointestinal smooth muscle contributing to NO-dependent relaxation. Part of cGMP kinase signaling complex at least composed of ACTA2/alpha-actin, CNN1/calponin H1, PLN/phospholamban, PRKG1 and ITPR1 (By similarity). Interacts with PRKG1/cGKI-beta and ITPR1/IP3R type I. Highly expressed in smooth muscle such as aorta, colon and uterus. Detected in the brain, in the thalamus, in the hippocampus and myenteric plexus. Highly expressed in megakaryocytes. Down-regulated during macrophage differentiation. Phosphorylated by PRKG1/cGKI. Mice lacking coiled-coil region N-terminal part exhibit disruption of IRAG1-ITPR1 interaction. They have dilated gastrointestinal tract and disturbed gastrointestinal motility. Smooth muscle are no more relaxed by cGMP after phenilephrine-induced contraction and half of the homozygous mice dies before the age of 6 months. Nitric oxide (NO) and cGMP-mediated inhibition of collagen-induced platelet aggregation is strongly suppressed in platelets of these transgenic mice. growth. IRAG1 gene is a common integration site of murine leukemia virus, leading to induce myeloid leukemia in BXH2 mice. Murine leukemia virus integration occurs at the 5' end of the gene between 2 differentially used promoters and thus probably alters the expression of an important gene for myeloid cell growth.