Nomenclature	P2Y 1 receptor	P2Y 2 receptor	P2Y 4 receptor	P2Y 6 receptor
HGNC, UniProt	P2RY1, P47900	P2RY2, P41231	P2RY4, P51582	P2RY6, Q15077
Potency order of endogenous ligands	ADP>ATP	uridine triphosphate>ATP [1112]	uridine triphosphate>ATP (at rat recombinant receptors, UTP = ATP)	uridine diphosphate≫uridine triphosphate>ADP
Endogenous agonists	–	uridine triphosphate [989, 1112]	–	–
Agonists	ADP βS [1921], 2MeSADP [1729, 2054]	–	–	–
Sub/family‐selective agonists	–	diquafosol [1554], denufosol [1113, 1554, 2181], UTP γS [1112]	diquafosol [240], denufosol [2181], UTP γS [1113]	–
Selective agonists	MRS2365 [329], 2‐Cl‐ADP( α‐BH3) [76]	MRS2698 [874], 2‐thioUTP [498], PSB1114 (EC50 value determined using an IP3 functional assay) [498, 499, 873]	MRS4062 [1276], MRS2927 [1276], (N)methanocarba‐UTP [989]	Rp‐5‐OMe‐UDP αB [644, 702], MRS2957 [1275], MRS2693 [146]
Antagonists	suramin (pK i 5.3) [2054], PPADS (pK i 5.2) [2054]	–	ATP (pK d 6.2) [970]	–
Sub/family‐selective antagonists	–	reactive blue‐2 (pIC50 6) [892], suramin (pIC50 4.3) [892, 1729]	PPADS (pEC50 2–5) [881], reactive blue‐2 (pIC50 4.7) [171] – Rat	reactive blue‐2 (pK B 6) [2045], PPADS (pK B 4) [2045], suramin (pK B 4) [2045]
Selective antagonists	MRS2500 (pK i 8.8–9.1) [286, 988], MRS2279 (pK i 7.9) [2054], MRS2179 (pK i 7–7.1) [203, 2054]	AR‐C118925XX (pIC50∼6) [968], AR‐C126313 (pEC50 6) [874], PSB‐416 (pIC50 4.7) [792]	ATP (pK d 6.2) [970]	MRS2578 (pIC50 7.4) [1257], MRS2567 (pIC50 6.9) [1257]
Allosteric modulators	2,2'‐pyridylisatogen tosylate (Negative) (pIC50 7.8) [601]	–	–	–
Selective allosteric modulators	BMS compound 16 (Negative) (pK i 6.9) [2206]	–	–	–
Labelled ligands	[3 H]MRS2279 (Antagonist) (pK d 8.1) [2054], [3 H]2MeSADP (Agonist) [1921], [35 S]ADP βS (Agonist)	–	–	MRS4162 (Selective Antagonist) (pEC50 7.6) [897]