P2X4: ProductsP2RX4 belongs to the family of purinoceptors for ATP. It functions as a ligand-gated ion channel with high calcium permeability. The main pharmacological distinction between the members of the purinoceptor family is the relative sensitivity to the antagonists suramin and PPADS. P2RX4 has the lowest sensitivity for these antagonists. Multiple alternatively spliced transcript variants have been identified for P2RX4.