title: Validation of cryo-EM structure of IP₃R1 channel.
abstract: About a decade ago, three electron cryomicroscopy (cryo-EM) single-particle reconstructions of IP3R1 were reported at low resolution. It was disturbing that these structures bore little similarity to one another, even at the level of quaternary structure. Recently, we published an improved structure of IP3R1 at ∼1 nm resolution. However, this structure did not bear any resemblance to any of the three previously published structures, leading to the question of why the structure should be considered more reliable than the original three. Here, we apply several methods, including class-average/map comparisons, tilt-pair validation, and use of multiple refinement software packages, to give strong evidence for the reliability of our recent structure. The map resolution and feature resolvability are assessed with the gold standard criterion. This approach is generally applicable to assessing the validity of cryo-EM maps of other molecular machines.
authors.affiliation: Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Murray
authors.forename: John
authors.initials: J
authors.lastname: Flanagan
authors.forename: Olga B
authors.initials: OB
authors.lastname: Popova
authors.forename: Wah
authors.initials: W
authors.lastname: Chiu
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Ludtke
authors.forename: Irina I
authors.initials: II
authors.lastname: Serysheva
mesh_terms: D020285:Cryoelectron Microscopy / Q000379:methods*; D018360:Crystallography, X-Ray; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D053496:Inositol 1,4,5-Trisphosphate Receptors