Receptor for prostacyclin (prostaglandin I2 or PGI2). The activity of this receptor is mediated by G(s) proteins which activate adenylate cyclase. Interacts (non-isoprenylated C-terminus) with PDZK1. Isoprenylation does not influence ligand binding but is required for efficient coupling to the effectors adenylyl cyclase and phospholipase C. Belongs to the G-protein coupled receptor 1 family.