[Isoform 6]: ATP-gated nonselective transmembrane cation channel permeable to potassium, sodium and calcium (PubMed:12761352). Unlike, other P2RX receptors, the P2X5 receptor is also permeable to chloride (PubMed:12761352). May play a supporting role in the inflammatory response (By similarity). ; [Isoform 1]: Non-functional.