Table 1. Thermodynamic cost of P2X2-TM integration.
| Region analysed | ΔGpred | ΔGapp | Sequence |
| TM1prestruc | −0.45 | −1.4 | FVHRMVQLLILLYFVWYVFI |
| TM1struc | −0.17 | n.d. | RMVQLLILLYFVWYVFIVQ |
| TM1ΔGpred (std) | −0.82 | n.d. | LGFVHRMVQLLILLYFVWYVFIV |
| TM2prestruc | +0.22 | +1.1 | IINLATALTSIGVGSFLCDWILL |
| TM2prestruc (D349A) | −0.50 | −1.1 | IINLATALTSIGVGSFLCAWILL |
| TM2struc | +2.50 | +1.4 | LIPTIINLATALTSIGVGSFL(CD) |
| TM2ΔGpred (std) | −0.12 | n.d. | LATALTSIGVGSFLCDWILLTFM |
| TM2ΔGpred (opt) | −0.66 | +0.7 | TIINLATALTSIGVGSFLCDWILLTFM |
| TM2ΔGpred (opt) with flanks | −0.66 | −2.0 | GIRIDVIVHGQAGKFSLIPTIINLATALTSIGVGSFLCDWILLTFMNKNKLYSHKKFDKVRTP |
The predicted (ΔGpred) and experimentally determined (ΔGapp) energetic cost in kcal/mol of inserting versions of the first (TM1) and second (TM2) transmembrane-spanning regions of P2X2 when located in a Lep-derived model precursor (cf. supplementary material Fig. S2). In each case, the underlined sequences indicate residues presumed to reside within the plane of the membrane. Residue D349 is shown in bold, and in the case of TM2struc is bracketed and in italics to indicate it is excluded from this sequence together with the preceding cysteine residue. In the case of TM2ΔGpred with flanks, the P2X2-derived sequences adjacent to the core TM region are not underlined. Certain predicted values are provided solely for the basis of comparison and, in these cases, the actual values have not been experimentally determined (n.d.).