Functional properties of recombinant homomeric P2X receptors
| Homomeric Receptor Type | |||||||
|---|---|---|---|---|---|---|---|
| P2X1 | P2X2 | P2X3 | P2X4 | P2X5 | P2X6 | P2X7 | |
| Agonist EC50 (μM) | |||||||
| ATP | 1 | 1–30 | 1 | 10 | 10 | 12 | 100 |
| 2MeSATP | 1 | 3 | 0.3 | 10–100 | 10 | 9 | 10 |
| αβ-meATP | 1–3 | >300 | 1 | >300 | >300 | >100 | >300 |
| BZ-ATP | 3 | 30 | >500 | >500 | 3 | ||
| Antagonist IC50 (μM) | |||||||
| Suramin | 1 | 10 | 3 | >500 | 4 | >100 | 500 |
| PPADS | 1 | 1 | 1 | >500 | 3 | >100 | 50 |
| TNP-ATP | 0.006 | 1 | 0.001 | 15 | >30 | ||
| NF023 | 0.2 | >10 | 8.5 | >100 | |||
| Calmidazolium | 0.065 | ||||||
| IP5I | 0.003 | No block | 2.8 | Potentiation | |||
| Brilliant Blue G | >5 | 1.4 | >10 | >10 | 0.01 | ||
| Modulator EC50 (μM) | |||||||
| Ivermectin | >30 | >30 | 0.25 | >30 | |||
| Cibacron blue | Block IC50 ∼0.7 μM | Potentiation | Potentiation and block | ||||
| Ion effects | |||||||
| Zn2+ | Increase EC50 6.9 μM | Increase 2 μM | Decrease 10 μM | ||||
| H+ | Decrease p Ka 6.3 | IncreasepKa 7.3 | Decrease pKa 6.0 | DecreasepKa 6.8 | Decrease pKa 6.1 | ||
| Ca2+ | No effect >100 mM | Block IC50 87 mM | Block IC50 15 mM | Decrease 7 mM | Decrease 3 mM | ||
Data are derived from the following references: agonists and antagonists (Valera et al., 1994; Bo et al., 1995; Chen et al., 1995;Lewis et al., 1995; Buell et al., 1996b; Collo et al., 1996, 1997;Séguéla et al., 1996; Soto et al., 1996a,b; Surprenant et al., 1996; Radford et al., 1997; Rassendren et al., 1997b; Virginio et al., 1997; Chessell et al., 1998a; Egan et al., 1998; Le et al., 1998a,1999; Torres et al., 1998b; Alexander et al., 1999; Haines et al., 1999; King et al., 1999; Townsend-Nicholson et al., 1999; Boue-Grabot et al., 2000; Dunn et al., 2000; Jones et al., 2000); modulators (Miller et al., 1998; Khakh et al., 1999b); ionic effects (Stoop et al., 1997; Virginio et al., 1997, 1998a; Wildman et al., 1997, 1998,1999; Ding and Sachs, 1999b, 2000; Xiong et al., 1999); and species differences—note marked species differences between various orthologues for both agonist and antagonist potencies (see text andChessell et al., 1998a,b; Hibell et al., 2000; Jones et al., 2000).