The P2X receptors belong to the ligand-gated ion channel family and are activated by extracellular ATP.The structure and function of the P2X receptors, which were mainly investigated using in vitro models, show their involvement in synaptic communication, cell death, and differentiation.Seven mammalian P2X receptor subtypes (P2X1–P2X7) have been identified and cloned1-3. All P2X receptor subtypes share the same structure of intracellular N- and C-termini, two membrane-spanning domains and a large extracellular loop. All P2X subtypes can assemble to form homomeric or heteromeric functional channels with the exception of P2X6, which only seems to function as part of a heteromeric complex
