May be a receptor for inositol 1,4,5 trisphosphate which governs calcium fluxes from the endoplasmic reticulum stores into the cytosol. May be involved in autophagic cell death. Expression is low during growth and rises to a peak at 9 hours of development when chemotactic aggregation to cyclic AMP is near its height; levels then decrease through the end of development. Null cells show abolition of calcium entry in response to chemoattractant, response to cyclic AMP and normal increase in free cytosolic calcium that follows chemotactic stimulation. Cells show formation of smaller fruiting bodies and abolition of autophagic cell death. Cells show absence of vacuolization. Belongs to the InsP3 receptor family.