Claim: P2RX7 (a protein that in humans is encoded by the P2RX7 gene) subunits can form homomeric receptors and the receptor is a ligand-gated cation channel which requires lower levels of ATP.
Evidence: The P2X7 receptor requires higher levels of ATP than other P2X receptors; however, the response can be potentiated by reducing the concentration of divalent cations such as calcium or magnesium.