Fig. S1.

Crystallography of the large cytosolic domain of IP₃R. (A) Bipyramidal crystals of IP₃R1585 (Left) and an X-ray diffraction image measured from the crystal (Center). (Right) Magnification of the boxed area. (B) Structure determination statistics of IP₃R2217 and IP₃R1585 by molecular replacement. The polyalanine (PolyA) models refined in the C222₁^#, P4₂2₁2^##, and P4₂^### crystal lattices were used as search models. (C) Electron density maps in gray (2Fo-Fc, contoured at 1.5 σ) or in green (Fo-Fc, contoured at 3.0 σ), calculated from molecular replacement of the C222₁ dataset using each search model presented in the upper table. Note that the residual electron density outside the search model was visible in 2Fo-Fc and Fo-Fc maps. LLG, log-likelihood gain; TFZ, translation function z-score.