Docking of ADPR to the NUDT9-H domain of TRPM2. (A) The tertiary structure of human NUDT9 (gray) and the model of NUDT9-H domain. (B) Chemical structures of ADPR. The terminal ribose is circled with orange; the pyrophosphate is boxed with green; and the adenosine is circled with blue. (C) Ribbon presentation of the binding pocket in the NUDT9-H domain (gray) docked with ADPR. The key residues mediating binding of ADPR are highlighted. (D) MD simulation of the NUDT9-H domain in complex with ADPR: the root mean square deviation (RMSD) of ADPR (red) and ADPR-binding protein (black), respectively.