FIGURE 5.

Identification of two residues in the carboxyl tail of P2X4 subunits is required for the cross-inhibition. A, P2X4 subunit sequence of the N- and C-terminal tails is shown. Identified residues crucial for the cross-talk are underlined. B, a summary bar graph represents the percentage of current inhibition for wild-type and mutated P2X4 receptors (by deletion Δ or substitution) co-expressed with α2β3 GABA subunits recorded during co-application of ATP + GABA (100 μm each); *, p < 0.05; the number of cells is indicated between the parentheses; nf, non functional mutants. C, representative traces of additive currents recorded between mutant P2X4 Y374S/V375T and GABA_A (α2β3) receptors (HP = −60 mV) show that Tyr³⁷⁴ and Val³⁷⁵ are essential for the molecular interaction between P2X4 and GABA_A receptors.