5-Hydroxytryptamine Inhibits P2X2 Receptor Channel Pore Mutants

1.5-Hydroxytryptamine (10 M) enhanced ionic current mediated through the wild-type P2X₂ receptor/channel expressed in Xenopus oocytes.2.5-Hydroxytryptamine (10 M) inhibited a current mediated through P2X₂ receptor/channel mutants when Thr³³⁰ or Asn³³³ was replaced with Ile (T330I and N333I).3.Our results suggest that neutralization of Thr³³⁰ or Asn³³³ exposes a high-affinity, inhibitory binding site for 5-hydroxytryptamine. This implies that 5-hydroxytryptamine interacts with the P2X₂ receptor/channel at their channel pores.