Receptor for UTP and UDP coupled to G-proteins that activate a phosphatidylinositol-calcium second messenger system. Not activated by ATP or ADP. Pancreas. Phosphorylation of Ser-333 and Ser-334 is a key step in agonist-dependent desensitization and loss of surface P2RY4. This phosphorylation does not involve PKC, nor other calcium activated kinases. Belongs to the G-protein coupled receptor 1 family.