The three-dimensional reconstructions of (a) EDTA-hsTRPM2, (b) ADPR-hsTRPM2, (c) ADPR/Ca2+-hsTRPM2, and (d) 8-Br-cADPR/Ca2+-hsTRPM2. The unsharpened reconstructions are shown as transparent envelopes. One subunit is highlighted. (e–h) Atomic models of the corresponding reconstructions in panels a-d. The NUDT9-H domains are shown in solid surface, the MHR1/2 domains are shown in transparent surface, and the rest of the proteins are shown in cartoon representation. Ca2+, ADPR1, ADPR2, and 8-Br-cADPR are shown in purple, green, blue, and orange spheres, respectively. The center-of-mass (COM) of the MHR1/2 domain of one subunit in each structure is shown as a circle filled with white. The dimensions of the proteins and the difference between COMs along the pore axis are labeled.