+ Open data
Open data
- Basic information
Basic information
| Entry | Database: EMDB / ID: EMD-21432 | |||||||||||||||
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| Title | bestrophin-2 Ca2+-bound state (5 mM Ca2+) | |||||||||||||||
|  Map data | bestrophin-2 (BEST2) calcium-bound state (5 mM Ca2+) | |||||||||||||||
|  Sample | 
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|  Keywords | Chloride Channel / MEMBRANE PROTEIN | |||||||||||||||
| Function / homology |  Function and homology information Stimuli-sensing channels / intracellularly ligand-gated monoatomic ion channel activity / ligand-gated monoatomic anion channel activity / bicarbonate channel activity / bicarbonate transport / ligand-gated monoatomic cation channel activity / chloride channel activity / chloride channel complex / basolateral plasma membrane / plasma membrane Similarity search - Function | |||||||||||||||
| Biological species |   Bos taurus (domestic cattle) | |||||||||||||||
| Method | single particle reconstruction / cryo EM / Resolution: 2.36 Å | |||||||||||||||
|  Authors | Owji AP / Zhao Q | |||||||||||||||
| Funding support |  United States, 4 items 
 | |||||||||||||||
|  Citation |  Journal: Nat Struct Mol Biol / Year: 2020 Title: Structural and functional characterization of the bestrophin-2 anion channel. Authors: Aaron P Owji / Qingqing Zhao / Changyi Ji / Alec Kittredge / Austin Hopiavuori / Ziao Fu / Nancy Ward / Oliver B Clarke / Yin Shen / Yu Zhang / Wayne A Hendrickson / Tingting Yang /    Abstract: The bestrophin family of calcium (Ca)-activated chloride (Cl) channels, which mediate the influx and efflux of monovalent anions in response to the levels of intracellular Ca, comprises four members ...The bestrophin family of calcium (Ca)-activated chloride (Cl) channels, which mediate the influx and efflux of monovalent anions in response to the levels of intracellular Ca, comprises four members in mammals (bestrophin 1-4). Here we report cryo-EM structures of bovine bestrophin-2 (bBest2) bound and unbound by Ca at 2.4- and 2.2-Å resolution, respectively. The bBest2 structure highlights four previously underappreciated pore-lining residues specifically conserved in Best2 but not in Best1, illustrating the differences between these paralogs. Structure-inspired electrophysiological analysis reveals that, although the channel is sensitive to Ca, it has substantial Ca-independent activity for Cl, reflecting the opening at the cytoplasmic restriction of the ion conducting pathway even when Ca is absent. Moreover, the ion selectivity of bBest2 is controlled by multiple residues, including those involved in gating. | |||||||||||||||
| History | 
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- Structure visualization
Structure visualization
| Movie | 
 
 
  Movie viewer | 
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| Structure viewer | EM map:  SurfView  Molmil  Jmol/JSmol | 
| Supplemental images | 
- Downloads & links
Downloads & links
-EMDB archive
| Map data |  emd_21432.map.gz | 95.6 MB |  EMDB map data format | |
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| Header (meta data) |  emd-21432-v30.xml  emd-21432.xml | 17.9 KB 17.9 KB | Display Display |  EMDB header | 
| Images |  emd_21432.png | 79.8 KB | ||
| Filedesc metadata |  emd-21432.cif.gz | 5.6 KB | ||
| Others |  emd_21432_additional.map.gz  emd_21432_half_map_1.map.gz  emd_21432_half_map_2.map.gz | 75.1 MB 139 MB 139 MB | ||
| Archive directory |  http://ftp.pdbj.org/pub/emdb/structures/EMD-21432  ftp://ftp.pdbj.org/pub/emdb/structures/EMD-21432 | HTTPS FTP | 
-Validation report
| Summary document |  emd_21432_validation.pdf.gz | 1 MB | Display |  EMDB validaton report | 
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| Full document |  emd_21432_full_validation.pdf.gz | 1 MB | Display | |
| Data in XML |  emd_21432_validation.xml.gz | 15.1 KB | Display | |
| Data in CIF |  emd_21432_validation.cif.gz | 17.1 KB | Display | |
| Arichive directory |  https://ftp.pdbj.org/pub/emdb/validation_reports/EMD-21432  ftp://ftp.pdbj.org/pub/emdb/validation_reports/EMD-21432 | HTTPS FTP | 
-Related structure data
| Related structure data |  6vx7MC  6vx5C  6vx6C  6vx8C  6vx9C M: atomic model generated by this map C: citing same article ( | 
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| Similar structure data | 
- Links
Links
| EMDB pages |  EMDB (EBI/PDBe) /  EMDataResource | 
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- Map
Map
| File |  Download / File: emd_21432.map.gz / Format: CCP4 / Size: 103 MB / Type: IMAGE STORED AS FLOATING POINT NUMBER (4 BYTES) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Annotation | bestrophin-2 (BEST2) calcium-bound state (5 mM Ca2+) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Projections & slices | Image control
 
 Images are generated by Spider. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Voxel size | X=Y=Z: 0.41499 Å | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Density | 
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| Symmetry | Space group: 1 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Details | EMDB XML: 
 CCP4 map header: 
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-Supplemental data
-Additional map: Additional map
| File | emd_21432_additional.map | ||||||||||||
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| Annotation | Additional map | ||||||||||||
| Projections & Slices | 
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| Density Histograms | 
-Half map: half-volume 1
| File | emd_21432_half_map_1.map | ||||||||||||
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| Annotation | half-volume 1 | ||||||||||||
| Projections & Slices | 
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| Density Histograms | 
-Half map: half-volume 2
| File | emd_21432_half_map_2.map | ||||||||||||
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| Annotation | half-volume 2 | ||||||||||||
| Projections & Slices | 
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| Density Histograms | 
- Sample components
Sample components
-Entire : bestrophin-2 (BEST2) calcium-bound state (5 mM Ca2+)
| Entire | Name: bestrophin-2 (BEST2) calcium-bound state (5 mM Ca2+) | 
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| Components | 
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-Supramolecule #1: bestrophin-2 (BEST2) calcium-bound state (5 mM Ca2+)
| Supramolecule | Name: bestrophin-2 (BEST2) calcium-bound state (5 mM Ca2+) / type: cell / ID: 1 / Parent: 0 / Macromolecule list: #1 | 
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| Source (natural) | Organism:   Bos taurus (domestic cattle) | 
-Macromolecule #1: Bestrophin
| Macromolecule | Name: Bestrophin / type: protein_or_peptide / ID: 1 / Number of copies: 5 / Enantiomer: LEVO | 
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| Source (natural) | Organism:   Bos taurus (domestic cattle) | 
| Molecular weight | Theoretical: 47.424754 KDa | 
| Recombinant expression | Organism:  Homo sapiens (human) | 
| Sequence | String: MTVTYTARVA KARFGGFSKL LLLWRGSIYK LLWRELLCFL GLFMALSAAY RFVLTEEQKR YFEKLVLYCD RYASLIPVSF  VLGFYVTLV VHRWWNQYLS MPLTDALMCV VVGTVHGHDE RGRLYRRTLM RYAGLSGVLI LRSVSTAVFK RFPTIDHVVE A GFMTREER  ...String: MTVTYTARVA KARFGGFSKL LLLWRGSIYK LLWRELLCFL GLFMALSAAY RFVLTEEQKR YFEKLVLYCD RYASLIPVSF  VLGFYVTLV VHRWWNQYLS MPLTDALMCV VVGTVHGHDE RGRLYRRTLM RYAGLSGVLI LRSVSTAVFK RFPTIDHVVE A GFMTREER KKFENLNSSY NKYWVPCVWF CNLAAQARRE GRIRDNGAFK LLLEELNVFR SKCGMLFHYD WISVPLVYTQ VV TIAVYSY FLACLIGRQF LDPAQGYKDH DLDLCVPIFT LLQFFFYAGW LKVAEQLINP FGEDDDDFET NFLIDRCFQV SML AVDEMY DDLAMLEKDL YWDAAEARAP YTAATAFLMQ QPSFQGSTFD ITLAKEDMQF QRQDGLEAPL NEAHGDFLQR LLPV GTGMG TGGLL UniProtKB: Bestrophin-2 | 
-Macromolecule #2: CALCIUM ION
| Macromolecule | Name: CALCIUM ION / type: ligand / ID: 2 / Number of copies: 5 / Formula: CA | 
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| Molecular weight | Theoretical: 40.078 Da | 
-Macromolecule #3: CHLORIDE ION
| Macromolecule | Name: CHLORIDE ION / type: ligand / ID: 3 / Number of copies: 1 / Formula: CL | 
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| Molecular weight | Theoretical: 35.453 Da | 
-Macromolecule #4: water
| Macromolecule | Name: water / type: ligand / ID: 4 / Number of copies: 465 / Formula: HOH | 
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| Molecular weight | Theoretical: 18.015 Da | 
| Chemical component information |  ChemComp-HOH:  | 
-Experimental details
-Structure determination
| Method | cryo EM | 
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|  Processing | single particle reconstruction | 
| Aggregation state | particle | 
- Sample preparation
Sample preparation
| Concentration | 0.8 mg/mL | 
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| Buffer | pH: 7.8 | 
| Vitrification | Cryogen name: ETHANE | 
- Electron microscopy
Electron microscopy
| Microscope | FEI TITAN KRIOS | 
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| Image recording | Film or detector model: GATAN K3 (6k x 4k) / Detector mode: COUNTING / Average electron dose: 58.0 e/Å2 | 
| Electron beam | Acceleration voltage: 300 kV / Electron source:  FIELD EMISSION GUN | 
| Electron optics | Illumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD | 
| Experimental equipment |  Model: Titan Krios / Image courtesy: FEI Company | 
- Image processing
Image processing
| Startup model | Type of model: NONE | 
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| Final reconstruction | Applied symmetry - Point group: C5 (5 fold cyclic) / Resolution.type: BY AUTHOR / Resolution: 2.36 Å / Resolution method: FSC 0.143 CUT-OFF / Software - Name: cryoSPARC (ver. 2.13.2) / Number images used: 332270 | 
| Initial angle assignment | Type: ANGULAR RECONSTITUTION | 
| Final angle assignment | Type: ANGULAR RECONSTITUTION | 
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