Table 1.
Effect of pre-application and co-application of cadmium ion on alanine and cysteine rP2X4R mutants.
| Receptor | EC50 (μM) | Imax (nA) | Protocol 1 (%) | Protocol 2 (%) |
|---|---|---|---|---|
| WT | 2.3 ± 0.4 | 2.3 ± 0.2 | 100 ± 14 | 122 ± 3 |
| V47A | 5.2 ± 0.7 | 2.1 ± 0.2 | – | #133 ± 3 |
| V47C | 2.3 ± 0.7 | 2.8 ± 0.5 | 114 ± 15 | #199 ± 3* |
| F48A | 2.4 ± 0.3 | 2.3 ± 0.2 | – | #99 ± 1* |
| F48C | 2.0 ± 0.9 | 2.9 ± 0.5 | 111 ± 13 | #104 ± 1* |
| W50A | 3.6 ± 0.3 | 1.9 ± 0.2 | – | #147 ± 6* |
| W50C | 4.4 ± 0.8 | 2.2 ± 0.8 | 100 ± 16 | #157 ± 5* |
| E51A | 1.6 ± 0.6 | 1.2 ± 0.2* | – | #41 ± 6* |
| E51C | 3.5 ± 0.5 | 2.1 ± 0.5 | 150 ± 20* | #134 ± 5 |
| K52A | 3.1 ± 1.1 | 3.0 ± 0.4 | – | #128 ± 4 |
| K52C | 2.4 ± 0.6 | 2.6 ± 0.4 | 111 ± 23 | #132 ± 3 |
| G53A | 2.8 ± 0.6 | 2.9 ± 0.3 | – | #121 ± 4 |
| G53C | 3.8 ± 0.5 | 2.2 ± 0.5 | 100 ± 16 | #162 ± 3* |
| E56A | 2.0 ± 0.9 | 1.6 ± 0.2 | – | #134 ± 4 |
| E56C | 3.9 ± 0.7 | 1.9 ± 0.2 | 262 ± 45* | #222 ± 18* |
| T57A | 1.9 ± 0.6 | 2.2 ± 0.3 | – | #109 ± 2 |
| T57C | 2.0 ± 0.3 | 1.9 ± 0.2 | 162 ± 20* | #130 ± 3 |
| D58A | 3.2 ± 1.3 | 0.6 ± 0.1* | – | #100 ± 1* |
| D58C | 2.3 ± 0.9 | 0.9 ± 0.1* | 84 ± 30 | #91 ± 2* |
| S59A | 2.9 ± 1.3 | 2.6 ± 0.4 | – | #102 ± 2* |
| S59C | 2.0 ± 0.5 | 2.5 ± 0.3 | 220 ± 32* | #96 ± 1* |
| V60A | 2.4 ± 0.6 | 2.3 ± 0.4 | – | #101 ± 1* |
| V60C | 2.1 ± 0.8 | 2.6 ± 0.5 | 116 ± 18 | #100 ± 1* |
| V61A | 2.9 ± 0.4 | 2.1 ± 0.3 | – | #116 ± 2 |
| V61C | 3.7 ± 1.5 | 2.5 ± 0.3 | 166 ± 22* | #117 ± 2 |
| %WT | 2.3 ± 0.4 | 2.3 ± 0.2 | 100 ± 14 | #122 ± 3 |
| K326A | 1.7 ± 0.6 | 1.9 ± 0.3 | 175 ± 34* | #126 ± 2 |
| K326C | 2.4 ± 0.6 | 1.3 ± 0.2 | #129 ± 2 | |
| G328A | 2.6 ± 0.9 | 1.9 ± 0.5 | 107 ± 16 | #114 ± 2 |
| G328C | 2.7 ± 0.6 | 2.2 ± 0.3 | #111 ± 4 | |
| K329A | 4.9 ± 1.5 | 1.4 ± 0.1 | 43 ± 20* | #125 ± 3 |
| K329C | 4.0 ± 1.2 | 1.8 ± 0.3 | #55 ± 4* | |
| F330A | 3.2 ± 1.2 | 1.5 ± 0.3 | 100 ± 13 | #118 ± 2 |
| F330C | 4.0 + 1.2 | 0.8 ± 0.1* | #121 ± 2 | |
| D331A | 1.5 ± 0.2 | 1.8 ± 0.3 | #120 ± 2 | |
| D331C | 2.1 ± 0.2 | 2.3 ± 0.4 | 100 ± 15 | #64 ± 3* |
| I332A | 1.3 ± 0.3 | 1.5 ± 0.4 | 110 ± 21 | #100 ± 1* |
| I332C | 1.6 ± 0.3 | 2.2 ± 0.3 | #75 ± 2* | |
| I333A | 2.9 ± 0.8 | 1.6 ± 0.1 | 100 ± 22 | #101 ± 1* |
| I333C | 2.8 ± 1.1 | 1.9 ± 0.3 | #196 ± 15* | |
| P334A | 1.0 ± 0.3* | 1.3 ± 0.3 | 100 ± 35 | #101 ± 1* |
| P334C | 1.4 ± 0.4 | 0.6 ± 0.1* | #105 ± 1* | |
| T335A | 1.8 ± 0.6 | 2.2 ± 0.2 | 110 ± 21 | #121 ± 2 |
| T335C | 2.6 ± 0.5 | 1.8 ± 0.2 | #73 ± 2* | |
| M336A | 2.5 ± 0.3 | 2.2 ± 0.5 | 150 ± 20* | #104 ± 2* |
| M336C | 1.2 ± 0.2 | 2.3 ± 0.5 | #110 ± 1 | |
| I337A | 2.9 ± 1.3 | 2.0 ± 0.4 | 100 ± 31 | #128 ± 3 |
| I337C | 4.1 ± 0.6 | 1.0 ± 0.2* | #68 ± 5* | |
| N338A | 2.0 ± 0.2 | 3.5 ± 0.4* | 100 ± 25 | #125 ± 3 |
| N338C | 1.1 ± 0.2 | 3.2 ± 0.5* | #155 ± 4* |
The data are expressed as the mean ± SEM from 12 to 40 measurements per mutant and 96 measurements for the wild type (WT) receptor. The statistical significance was estimated by ANOVA followed by post hoc two-way t-test with Bonferroni correction, comparing the level of cadmium effect between WT and mutant receptors (*p < 0.05) and between alanine and cysteine mutants of the same residue (#p < 0.05). Fifth and fourth columns depict the percentage of ATP induced amplitude change elicited by 20 μM cadmium acquired by protocol 1 and protocol 2.