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Open data
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Basic information
Entry | Database: EMDB / ID: EMD-21434 | |||||||||||||||
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Title | Bestrophin-2 (BEST2) calcium-unbound state 1 (EGTA only) | |||||||||||||||
![]() | Bestrophin-2 (BEST2) calcium-free state 1 (EGTA only) | |||||||||||||||
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![]() | Chloride Channel / MEMBRANE PROTEIN | |||||||||||||||
Function / homology | ![]() intracellularly ligand-gated monoatomic ion channel activity / ligand-gated monoatomic anion channel activity / Stimuli-sensing channels / bicarbonate channel activity / bicarbonate transport / chloride channel activity / ligand-gated monoatomic cation channel activity / chloride channel complex / basolateral plasma membrane / plasma membrane Similarity search - Function | |||||||||||||||
Biological species | ![]() ![]() | |||||||||||||||
Method | single particle reconstruction / cryo EM / Resolution: 2.17 Å | |||||||||||||||
![]() | Owji AP / Zhao Q | |||||||||||||||
Funding support | ![]()
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![]() | ![]() 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
Movie |
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Structure viewer | EM map: ![]() ![]() ![]() |
Supplemental images |
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Downloads & links
-EMDB archive
Map data | ![]() | 134.6 MB | ![]() | |
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Header (meta data) | ![]() ![]() | 17.6 KB 17.6 KB | Display Display | ![]() |
Images | ![]() | 68.6 KB | ||
Filedesc metadata | ![]() | 5.6 KB | ||
Others | ![]() ![]() ![]() | 33.1 MB 59.3 MB 59.3 MB | ||
Archive directory | ![]() ![]() | HTTPS FTP |
-Related structure data
Related structure data | ![]() 6vx9MC ![]() 6vx5C ![]() 6vx6C ![]() 6vx7C ![]() 6vx8C M: atomic model generated by this map C: citing same article ( |
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Similar structure data |
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Links
EMDB pages | ![]() ![]() |
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Map
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Annotation | Bestrophin-2 (BEST2) calcium-free state 1 (EGTA only) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Voxel size | X=Y=Z: 0.35128 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_21434_additional.map | ||||||||||||
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Annotation | Additional map | ||||||||||||
Projections & Slices |
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Density Histograms |
-Half map: half-volume 1
File | emd_21434_half_map_1.map | ||||||||||||
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Annotation | half-volume 1 | ||||||||||||
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Density Histograms |
-Half map: half-volume 2
File | emd_21434_half_map_2.map | ||||||||||||
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Annotation | half-volume 2 | ||||||||||||
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Density Histograms |
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Sample components
-Entire : bestrophin-2 (BEST2) calcium-free state 1 (EGTA only)
Entire | Name: bestrophin-2 (BEST2) calcium-free state 1 (EGTA only) |
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Components |
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-Supramolecule #1: bestrophin-2 (BEST2) calcium-free state 1 (EGTA only)
Supramolecule | Name: bestrophin-2 (BEST2) calcium-free state 1 (EGTA only) / type: cell / ID: 1 / Parent: 0 / Macromolecule list: #1 |
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Source (natural) | Organism: ![]() ![]() |
-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: ![]() ![]() |
Molecular weight | Theoretical: 47.424754 KDa |
Recombinant expression | Organism: ![]() |
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: CHLORIDE ION
Macromolecule | Name: CHLORIDE ION / type: ligand / ID: 2 / Number of copies: 1 / Formula: CL |
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Molecular weight | Theoretical: 35.453 Da |
-Macromolecule #3: water
Macromolecule | Name: water / type: ligand / ID: 3 / Number of copies: 455 / 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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![]() | single particle reconstruction |
Aggregation state | particle |
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Sample preparation
Concentration | 0.8 mg/mL |
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Buffer | pH: 7.8 |
Vitrification | Cryogen name: ETHANE / Instrument: FEI VITROBOT MARK IV |
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Electron microscopy
Microscope | FEI TITAN KRIOS |
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Image recording | Film or detector model: GATAN K2 SUMMIT (4k x 4k) / Detector mode: COUNTING / Average electron dose: 69.67 e/Å2 |
Electron beam | Acceleration voltage: 300 kV / Electron source: ![]() |
Electron optics | Illumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD |
Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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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: 2.17 Å / Resolution method: FSC 0.143 CUT-OFF / Software - Name: cryoSPARC (ver. 2.13.2) / Number images used: 280524 |
Initial angle assignment | Type: ANGULAR RECONSTITUTION |
Final angle assignment | Type: ANGULAR RECONSTITUTION |