+Open data
-Basic information
Entry | Database: PDB / ID: 8tkf | ||||||||||||
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Title | Human Type 3 IP3 Receptor - Activated State (+IP3/ATP/JD Ca2+) | ||||||||||||
Components | Inositol 1,4,5-trisphosphate receptor type 3 | ||||||||||||
Keywords | TRANSPORT PROTEIN / Ion Channel / Calcium Channel / Endoplasmic Reticulum | ||||||||||||
Function / homology | Function and homology information sensory perception of bitter taste / sensory perception of umami taste / DAG and IP3 signaling / inositol 1,3,4,5 tetrakisphosphate binding / inositol 1,4,5-trisphosphate-gated calcium channel activity / sensory perception of sweet taste / platelet dense tubular network membrane / Effects of PIP2 hydrolysis / Elevation of cytosolic Ca2+ levels / PLC beta mediated events ...sensory perception of bitter taste / sensory perception of umami taste / DAG and IP3 signaling / inositol 1,3,4,5 tetrakisphosphate binding / inositol 1,4,5-trisphosphate-gated calcium channel activity / sensory perception of sweet taste / platelet dense tubular network membrane / Effects of PIP2 hydrolysis / Elevation of cytosolic Ca2+ levels / PLC beta mediated events / inositol hexakisphosphate binding / inositol 1,4,5 trisphosphate binding / nuclear outer membrane / CLEC7A (Dectin-1) induces NFAT activation / transport vesicle membrane / cytoplasmic side of endoplasmic reticulum membrane / brush border / intracellularly gated calcium channel activity / Role of phospholipids in phagocytosis / calcium ion homeostasis / Ion homeostasis / release of sequestered calcium ion into cytosol / FCERI mediated Ca+2 mobilization / FCGR3A-mediated IL10 synthesis / phosphatidylinositol binding / secretory granule membrane / VEGFR2 mediated cell proliferation / Antigen activates B Cell Receptor (BCR) leading to generation of second messengers / sarcoplasmic reticulum / Regulation of insulin secretion / long-term synaptic potentiation / memory / Sensory perception of sweet, bitter, and umami (glutamate) taste / response to calcium ion / Glucagon-like Peptide-1 (GLP1) regulates insulin secretion / sensory perception of taste / apical part of cell / myelin sheath / Ca2+ pathway / positive regulation of cytosolic calcium ion concentration / protein homotetramerization / receptor complex / G protein-coupled receptor signaling pathway / neuronal cell body / calcium ion binding / endoplasmic reticulum membrane / nucleolus / endoplasmic reticulum / nucleoplasm / membrane / plasma membrane / cytoplasm Similarity search - Function | ||||||||||||
Biological species | Homo sapiens (human) | ||||||||||||
Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 3.2 Å | ||||||||||||
Authors | Paknejad, N. / Sapuru, V. / Hite, R.K. | ||||||||||||
Funding support | United States, 3items
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Citation | Journal: Nat Commun / Year: 2023 Title: Structural titration reveals Ca-dependent conformational landscape of the IP receptor. Authors: Navid Paknejad / Vinay Sapuru / Richard K Hite / Abstract: Inositol 1,4,5-trisphosphate receptors (IPRs) are endoplasmic reticulum Ca channels whose biphasic dependence on cytosolic Ca gives rise to Ca oscillations that regulate fertilization, cell division ...Inositol 1,4,5-trisphosphate receptors (IPRs) are endoplasmic reticulum Ca channels whose biphasic dependence on cytosolic Ca gives rise to Ca oscillations that regulate fertilization, cell division and cell death. Despite the critical roles of IPR-mediated Ca responses, the structural underpinnings of the biphasic Ca dependence that underlies Ca oscillations are incompletely understood. Here, we collect cryo-EM images of an IPR with Ca concentrations spanning five orders of magnitude. Unbiased image analysis reveals that Ca binding does not explicitly induce conformational changes but rather biases a complex conformational landscape consisting of resting, preactivated, activated, and inhibited states. Using particle counts as a proxy for relative conformational free energy, we demonstrate that Ca binding at a high-affinity site allows IPRs to activate by escaping a low-energy resting state through an ensemble of preactivated states. At high Ca concentrations, IPRs preferentially enter an inhibited state stabilized by a second, low-affinity Ca binding site. Together, these studies provide a mechanistic basis for the biphasic Ca-dependence of IPR channel activity. | ||||||||||||
History |
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-Structure visualization
Structure viewer | Molecule: MolmilJmol/JSmol |
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-Downloads & links
-Download
PDBx/mmCIF format | 8tkf.cif.gz | 4.1 MB | Display | PDBx/mmCIF format |
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PDB format | pdb8tkf.ent.gz | Display | PDB format | |
PDBx/mmJSON format | 8tkf.json.gz | Tree view | PDBx/mmJSON format | |
Others | Other downloads |
-Validation report
Summary document | 8tkf_validation.pdf.gz | 2.1 MB | Display | wwPDB validaton report |
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Full document | 8tkf_full_validation.pdf.gz | 2.2 MB | Display | |
Data in XML | 8tkf_validation.xml.gz | 214.3 KB | Display | |
Data in CIF | 8tkf_validation.cif.gz | 324.4 KB | Display | |
Arichive directory | https://data.pdbj.org/pub/pdb/validation_reports/tk/8tkf ftp://data.pdbj.org/pub/pdb/validation_reports/tk/8tkf | HTTPS FTP |
-Related structure data
Related structure data | 41349MC 8tk8C 8tkdC 8tkeC 8tkgC 8tkhC 8tkiC 8tl9C 8tlaC M: map data used to model this data C: citing same article (ref.) |
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Similar structure data | Similarity search - Function & homologyF&H Search |
-Links
-Assembly
Deposited unit |
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1 |
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-Components
-Protein , 1 types, 4 molecules ABCD
#1: Protein | Mass: 304488.688 Da / Num. of mol.: 4 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: ITPR3 / Production host: Homo sapiens (human) / References: UniProt: Q14573 |
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-Non-polymers , 6 types, 36 molecules
#2: Chemical | ChemComp-ZN / #3: Chemical | ChemComp-I3P / #4: Chemical | ChemComp-CA / #5: Chemical | ChemComp-ATP / #6: Chemical | ChemComp-PCW / #7: Chemical | ChemComp-PT5 / [( |
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-Details
Has ligand of interest | Y |
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Has protein modification | Y |
-Experimental details
-Experiment
Experiment | Method: ELECTRON MICROSCOPY |
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EM experiment | Aggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction |
-Sample preparation
Component | Name: Human Type 3 IP3 Receptor / Type: COMPLEX Details: In the presence of saturating IP3, ATP, and Ca2+ titrated from 1 nM to 10 um Entity ID: #1 / Source: RECOMBINANT |
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Molecular weight | Value: 1.2 MDa / Experimental value: NO |
Source (natural) | Organism: Homo sapiens (human) |
Source (recombinant) | Organism: Homo sapiens (human) |
Buffer solution | pH: 8 Details: 120 mM NaCl, 50 mM Tris-HCl pH 8.0, 0.02% LMNG, 2 mM dithiothreitol, 2 mM EDTA, 2 mM EGTA, 2 mM BAPTA, 2 mM HEDTA, 1 mM ATP, 500 uM fluorinated fos-choline-8, 3 mM free Mg2+, 1-10000 nM free Ca2+ |
Specimen | Conc.: 20 mg/ml / Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES |
Vitrification | Instrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE / Humidity: 90 % / Chamber temperature: 277 K Details: Custom-made calcium free blotting paper (see publication for details). |
-Electron microscopy imaging
Experimental equipment | Model: Titan Krios / Image courtesy: FEI Company |
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Microscopy | Model: FEI TITAN KRIOS |
Electron gun | Electron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Illumination mode: FLOOD BEAM |
Electron lens | Mode: BRIGHT FIELD / Nominal magnification: 29000 X / Nominal defocus max: 2000 nm / Nominal defocus min: 1000 nm / Calibrated defocus min: 700 nm / Calibrated defocus max: 4300 nm / Cs: 2.7 mm / Alignment procedure: COMA FREE |
Specimen holder | Cryogen: NITROGEN / Specimen holder model: FEI TITAN KRIOS AUTOGRID HOLDER |
Image recording | Average exposure time: 3 sec. / Electron dose: 66 e/Å2 / Film or detector model: GATAN K3 (6k x 4k) / Num. of grids imaged: 6 / Num. of real images: 17733 Details: Images were collected at 0.826 A/px magnification on an FEI Krios with Gatan K3 detector at 15 e-/pix/sec with 3 sec exposure (0.05 sec/frame) for a total dose of 66 e-/A2 in automated ...Details: Images were collected at 0.826 A/px magnification on an FEI Krios with Gatan K3 detector at 15 e-/pix/sec with 3 sec exposure (0.05 sec/frame) for a total dose of 66 e-/A2 in automated fashion using SerialEM. Five datasets were collected during the same session for each Ca2+ concentration on a series of grids that were prepared sequentially resulting in 637 movies at 1 nM, 2150 movies at 10 nM, 6126 movies at 100 nM, 1372 movies at 1 uM, and 3136 movies at 10 uM. A sixth dataset of 4312 movies collected at nominal 100 nM free Ca2+ from a grid prepared later in the sequence was collected as a technical replicate to assess experimental error. |
-Processing
EM software |
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CTF correction | Type: PHASE FLIPPING AND AMPLITUDE CORRECTION | ||||||||||||||||
Symmetry | Point symmetry: C4 (4 fold cyclic) | ||||||||||||||||
3D reconstruction | Resolution: 3.2 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 228188 / Symmetry type: POINT | ||||||||||||||||
Atomic model building | Protocol: AB INITIO MODEL / Space: RECIPROCAL / Target criteria: Map to Model FSC | ||||||||||||||||
Refinement | Cross valid method: NONE |