Figure 5.

The domains required for desensitization are the same in P2X₃ and P2X₁ receptors. (A) Representative currents evoked by 10-s applications of ATP (100 μM) to oocytes expressing P2X₂ receptors, P2X₃ receptors, and a chimeric P2X₂/P2X₃ receptor. (B) Schematic representation of the portions of the P2X₃ receptor (hatched line) that were introduced into the P2X₂ receptor to produce desensitization. Mean currents in P2X₃ and chimera 22 were (measured in μA, number of oocytes in parentheses) 3.4 ± 1.2 (2) and 2.5 ± 0.7 (3), respectively. (C) Domains required to transfer desensitization include the hydrophobic, presumed membrane-spanning domains (M1, M2, and boxed) and 11–15 residues in the cytoplasmic region.