Histone H2b, H3, and H4, but not H2a, activate P2XR7 currents. (A and B) Representative trace of P2XR7 currents at −60 mV activated by purified recombinant human H2b (A), H3 (B, top), and H4 (B, bottom; 1 μg/ml, each). (C) Average histone-evoked current at −60 mV in control (Ctrl) and mouse P2XR7 (451L) expressing oocytes (n = 2–3 animals, 6–17 cells, P = 0.291 (H2a), P = 0.0002 (H2b), P = < 0.0001 (H3), P < 0.0001 (H4) by unpaired Student’s t test (P2XR7 expressing versus control).