Nomenclature	P2Y1 receptor	P2Y2 receptor	P2Y4 receptor	P2Y6 receptor
HGNC, UniProt	P2RY1, P47900	P2RY2, P41231	P2RY4, P51582	P2RY6, Q15077
Principal transduction	Gq/11	Gq/11	Gq/11	Gq/11
Rank order of potency	ADP>ATP	UTP=ATP	UTP>ATP (at rat recombinant receptors, UTP = ATP)	UDP>>UTP>ATP
Endogenous agonists (pKi)	–	–	–	UDP (pEC50 6.5) 1423
Selective agonists (pKi)	MRS2365 (pEC50 9.4) 1421, ADPβS (pEC50 7.3) 1459, 2MeSADP (pIC50 5.4 – 7.0) 1458,1461	2-thioUTP (pEC50 7.3) 1426, PSB1114 (pEC50 6.9) 1427, Ap4A (pEC50 6.1) 1419,1457, UTPγS (pEC50 5.8) 1443, MRS2768 (pEC50 5.7) 1441	UTPγS 1444, MRS4062 (pEC50 7.6) 1448	MRS2957 (pEC50 7.9) 1447, 5-iodoUDP (pEC50 7.82) 1416, 3-phenacyl-UDP (pEC50 7.2) 1426
Selective antagonists (pKi)	MRS2500 (8.8 – 9.1) 1420,1438, MRS2279 (7.9) 1461, MRS2179 (7.0 – 7.1) 1418,1461, 2,2'-pyridylisatogen tosylate (6.8) 1429	AR-C118925XX (pIC50 ∼6.0) 1436	ATP (pKd 6.2) 1437	MRS2578 (pIC50 7.4) 1445
Radioligands (Kd)	[35S]ADPβS (Agonist), [3H]2MeSADP (Agonist), [3H]MRS2279 (Antagonist) (8x10-9 M) 1461	–	–	–