Receptor for ADP and ATP coupled to G proteins that inhibit the adenylyl cyclase second messenger system. Not activated by UDP and UTP. Required for normal platelet aggregation and blood coagulation. {ECO:0000269|PubMed:11104774, ECO:0000269|PubMed:11196645, ECO:0000269|PubMed:11502873, ECO:0000269|PubMed:12578987, ECO:0000269|PubMed:24670650, ECO:0000269|PubMed:24784220}. This is the function of P2RY12 (purinergic receptor P2Y12, Ensembl gene identifier ENSG00000169313).