ATP-gated nonselective transmembrane cation channel that requires high millimolar concentrations of ATP for activation (PubMed:17483156, PubMed:25281740, PubMed:9038151). Upon ATP binding, it rapidly opens to allow the influx of small cations Na(+) and Ca(2+), and the K(+) efflux (PubMed:17483156, PubMed:20453110, PubMed:28235784, PubMed:39262850). Also has the ability to form a large pore in the cell membrane, allowing the passage of large cationic molecules (PubMed:17483156). In microglia, may mediate NADPH transport across the plasma membrane (PubMed:39142135). In immune cells, P2RX7 acts as a molecular sensor in pathological inflammatory states by detecting and responding to high local concentrations of extracellar ATP. In microglial cells, P2RX7 activation leads to the release of pro- inflammatory cytokines, such as IL-1beta and IL-18, through the activation of the NLRP3 inflammasome and caspase-1 (PubMed:26877061). Cooperates with KCNK6 to activate NLRP3 inflammasome (By similarity). Activates death pathways leading to apoptosis and autophagy (PubMed:21821797, PubMed:23303206, PubMed:28326637). Activates death pathways leading to pyroptosis (By similarity). {ECO:0000250|UniProtKB:Q9Z1M0, ECO:0000269|PubMed:17483156, ECO:0000269|PubMed:20453110, ECO:0000269|PubMed:21821797, ECO:0000269|PubMed:23303206, ECO:0000269|PubMed:25281740, ECO:0000269|PubMed:26877061, ECO:0000269|PubMed:28235784, ECO:0000269|PubMed:28326637, ECO:0000269|PubMed:39142135, ECO:0000269|PubMed:39262850, ECO:0000269|PubMed:9038151}. [Isoform B]: Shows ion channel activity but no macropore function. . [Isoform H]: Non-functional channel. . [Isoform J]: Non-functional channel. . This is the function of P2RX7 (purinergic receptor P2X 7, ENSG00000089041).