PMID:21827954

Citation	Ludtke, SJ, Tran, TP, Ngo, QT, Moiseenkova-Bell, VY, Chiu, W and Serysheva, II (2011) Flexible architecture of IP3R1 by Cryo-EM. Structure 19:1192-9
Abstract	Inositol 1,4,5-trisphosphate receptors (IP3Rs) play a fundamental role in generating Ca2+ signals that trigger many cellular processes in virtually all eukaryotic cells. Thus far, the three-dimensional (3D) structure of these channels has remained extremely controversial. Here, we report a subnanometer resolution electron cryomicroscopy (cryo-EM) structure of a fully functional type 1 IP3R from cerebellum in the closed state. The transmembrane region reveals a twisted bundle of four α helices, one from each subunit, that form a funnel shaped structure around the 4-fold symmetry axis, strikingly similar to the ion-conduction pore of K+ channels. The lumenal face of IP3R1 has prominent densities that surround the pore entrance and similar to the highly structured turrets of Kir channels. 3D statistical analysis of the cryo-EM density map identifies high variance in the cytoplasmic region. This structural variation could be attributed to genuine structural flexibility of IP3R1.
Links	PubMed PMC3154621 Online version:10.1016/j.str.2011.05.003
Keywords	Animals; Calcium/chemistry; Cerebellum/metabolism; Cryoelectron Microscopy; Inositol 1,4,5-Trisphosphate Receptors/chemistry; Inositol 1,4,5-Trisphosphate Receptors/isolation & purification; Inositol 1,4,5-Trisphosphate Receptors/metabolism; Inositol Phosphates/chemistry; Liposomes/chemistry; Protein Structure, Quaternary; Protein Structure, Secondary; Protein Structure, Tertiary; Rats; Surface Properties
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
RAT:ITPR1	enables	GO:0042802: identical protein binding	ECO:0000353: physical interaction evidence used in manual assertion	UniProtKB:P29994-1	F		Seeded From UniProt	complete

References

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