Fig. 1.

Representative heteromeric P2X₄₊₆channel current phenotype at day 3. A, ATP-induced currents after heterologous expression of P2X₄, P2X₆, and P2X₄ + P2X₆ (1:1 molar ratio) subunits recorded 3 d after corresponding cDNA nuclear microinjections in Xenopus oocytes.Arrows indicate beginnings of ATP applications (10 sec).B, P2X₄-dependent functional impact of P2X₆ on ATP-induced response (P2X₄ expressed alone; 1x, 5 ng of cDNA; 2x, 10 ng).C, P2X₁ receptor (P2X₁;1x, 5 ng; 2x, 10 ng) functional expression is unaffected by coexpressed P2X₆ subunits.D, P2X₂-mediated (P2X₂;1x, 5 ng; 2x, 10 ng) ATP-induced peak current amplitudes are unchanged in the presence of P2X₆subunits. (Averages ± SEM from 3 to 15 oocytes in 2–4 independent experiments; double asterisks denote significant difference; p < 0.01).