Receptor for extracellularly released ATP acting as a ligand-gated ion channel that plays multiple role in immunity and central nervous system physiology (PubMed:15985462, PubMed:24762105). Plays a key role in initial steps of T-cell activation and Ca(2+) microdomain formation (By similarity). Participates also in basal T-cell activity without TCR/CD3 stimulation (By similarity). Promotes the differentiation and activation of Th17 cells via expression of retinoic acid-related orphan receptor C/RORC (By similarity). Upon activation, drives microglia motility via the PI3K/Akt pathway (PubMed:12917686). Functional P2XRs are organized as homomeric and heteromeric trimers. Interacts with P2X7 (via C-terminus); this interaction is functional only in the presence of ATP (By similarity). Interacts with AP1M2 (PubMed:15985462). Widespread distribution in the brain. Strongly expressed in microglial cells (PubMed:12917686). Also expressed in epithelial cells (PubMed:8598206). By nerve injury. Belongs to the P2X receptor family.