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Protein Structures and Oligomeric States

Enter a protein name, UniProt accession or PDB ID. Name searches ask you to confirm the protein identity before related structures are queried.

Current Protein Identity：Q9H2S1 New Search
16PDB entries
18Biological assembly
51chain/assembly records
Main Difference Dimensions in This Set
Different construct Different mutation/modification Different assembly state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics

Difference tags compare only the current result set; every original PDB and assembly record remains separate.

Related-Structure Differences

Each row represents one biological assembly in one PDB entry; multiple monomers of the same protein are listed separately.

PDB Entry Assembly / Oligomeric State Construct Mutations and Modifications Ligands, Ions and Non-polymers Experimental Method Experimental Conditions Structure Quality
5V02 A positive allosteric modulator binding pocket in SK2 ion channels is shared by Riluzole and CyPPA Deposited 2017-02-28 Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric（2） Consistent with protein count
Chain B 395–486（92 aa） Fragment：UNP residues 395-486
Not recorded SO4 SULFATE ION × 2 657 6-(trifluoromethoxy)-1,3-benzothiazol-2-amine × 1 GOL GLYCEROL × 1 CA CALCIUM ION × 2 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；295 K；ammonia sulfate
Resolution 1.78 Å R-free 0.215
5V03 A positive allosteric modulator binding pocket in SK2 ion channels is shared by Riluzole and CyPPA Deposited 2017-02-28 Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric（2） Consistent with protein count
Chain B 395–486（92 aa） Fragment：UNP residues 395-486
Not recorded SO4 SULFATE ION × 1 658 N-(4-chlorophenyl)-2-(3,5-dimethyl-1H-pyrazol-1-yl)pyrimidin-4-amine × 1 CA CALCIUM ION × 2 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；295 K；ammonia sulfate
Resolution 1.58 Å R-free 0.220
5WBX Structural insights into the potency of SK/IK channel positive modulators Deposited 2017-06-29 Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric（2） Consistent with protein count
Chain B 395–486（92 aa）
Mutation：N407A SO4 SULFATE ION × 4 GOL GLYCEROL × 2 CA CALCIUM ION × 2 AJY (3Z)-6-bromo-3-(hydroxyimino)-5-methyl-1,3-dihydro-2H-indol-2-one × 1 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 5.8；293.15 K；0.1 M Sodium itrate tribasic dihydrate 0.5 M Ammonium sulfate 1.5 M Lithium sulfate monohydrate
Resolution 1.90 Å R-free 0.243
5WBX Structural insights into the potency of SK/IK channel positive modulators Deposited 2017-06-29 Assembly 2 Protein heterocomplex Heteromer；Protein × 4 PDB declaration: tetrameric（4） Consistent with protein count
Chain B 395–486（92 aa）
Mutation：N407A SO4 SULFATE ION × 8 GOL GLYCEROL × 4 CA CALCIUM ION × 4 AJY (3Z)-6-bromo-3-(hydroxyimino)-5-methyl-1,3-dihydro-2H-indol-2-one × 2 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 5.8；293.15 K；0.1 M Sodium itrate tribasic dihydrate 0.5 M Ammonium sulfate 1.5 M Lithium sulfate monohydrate
Resolution 1.90 Å R-free 0.243
5WC5 Structural insights into the potency of SK/IK channel positive modulators Deposited 2017-06-29 Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric（2） Consistent with protein count
Chain B 395–486（92 aa）
Mutation：N407A SO4 SULFATE ION × 6 GOL GLYCEROL × 1 CA CALCIUM ION × 2 AJV 7-fluoro-3-(hydroxyamino)-2H-indol-2-one × 1 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 5.8；293.15 K；0.1 M Sodium citrate tribasic dihydrate 0.5 M Ammonium sulfate 1.5 M Litium sulfate monohydrate
Resolution 2.30 Å R-free 0.250
5WC5 Structural insights into the potency of SK/IK channel positive modulators Deposited 2017-06-29 Assembly 2 Protein heterocomplex Heteromer；Protein × 4 PDB declaration: tetrameric（4） Consistent with protein count
Chain B 395–486（92 aa）
Mutation：N407A SO4 SULFATE ION × 12 GOL GLYCEROL × 2 CA CALCIUM ION × 4 AJV 7-fluoro-3-(hydroxyamino)-2H-indol-2-one × 2 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 5.8；293.15 K；0.1 M Sodium citrate tribasic dihydrate 0.5 M Ammonium sulfate 1.5 M Litium sulfate monohydrate
Resolution 2.30 Å R-free 0.250
6ALE A V-to-F substitution in SK2 channels causes Ca2+ hypersensitivity and improves locomotion in a C. elegans ALS model Deposited 2017-08-07 Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric（2） Consistent with protein count
Chain B 394–486（93 aa） Fragment：calmodulin binding domain (UNP residues 394-486)
Not recorded SO4 SULFATE ION × 4 1KP (3E)-6,7-dichloro-3-(hydroxyimino)-1,3-dihydro-2H-indol-2-one × 1 GOL GLYCEROL × 1 CA CALCIUM ION × 2 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 5.6；293.15 K；0.1 M Sodium Citrate Tribasic dehydrate 0.6 M Ammonium sulfate 1.4 M Lithium sulfate monohydrate
Resolution 2.50 Å R-free 0.255
9O48 Cryo-EM structure of the human SK2-4 chimera/calmodulin channel complex in the Ca2+ bound state Deposited 2025-04-08 Assembly 1 Insufficient information Heteromer；Protein × 8 PDB declaration: octameric（8） Consistent with protein count
Chain A 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Chain B 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Chain C 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Chain D 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Not recorded K POTASSIUM ION × 2 CA CALCIUM ION × 16 ELECTRON MICROSCOPY
cryo-EM buffer pH 8；20 mM Tris pH 8, 150 mM KCl, 2 mM CaCl2, 0.005% GDN, 0.0005% CHS
cryo-EM vitrification conditions Cryogen ETHANE；5 uL of sample was applied to grids at 4 degree temperature with 100% humidity. After 30 seconds, grids were blotted for 5 seconds with blot force 25 and plunged into liquid ethane.
Resolution 3.10 Å
9O51 Cryo-EM structure of the human SK2-4 chimera/calmodulin channel complex in the Ca2+ free state Deposited 2025-04-09 Assembly 1 Insufficient information Heteromer；Protein × 8 PDB declaration: octameric（8） Consistent with protein count
Chain A 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Chain B 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Chain C 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Chain D 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Not recorded K POTASSIUM ION × 2 CA CALCIUM ION × 4 ELECTRON MICROSCOPY
cryo-EM buffer pH 8；20 mM Tris pH 8, 150 mM KCl, 5 mM EGTA, 0.005% GDN, 0.0005% CHS
cryo-EM vitrification conditions Cryogen ETHANE；5 uL of sample was applied to grids at 4 degree temperature with 100% humidity. After 30 seconds, grids were blotted for 5 seconds with blot force 25 and plunged into liquid ethane.
Resolution 3.40 Å
9O52 Cryo-EM structure of the human SK2-4 chimera/calmodulin channel complex bound to the bee toxin apamin Deposited 2025-04-09 Assembly 1 Insufficient information Heteromer；Protein × 9 PDB declaration: nonameric（9） Consistent with protein count
Chain A 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Chain B 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Chain C 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Chain D 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Not recorded K POTASSIUM ION × 4 CA CALCIUM ION × 16 ELECTRON MICROSCOPY
cryo-EM buffer pH 8；20 mM Tris pH 8, 150 mM KCl, 2 mM CaCl2, 0.005% GDN, 0.0005% CHS
cryo-EM vitrification conditions Cryogen ETHANE；5 uL of sample was applied to grids at 4 degree temperature with 100% humidity. After 30 seconds, grids were blotted for 5 seconds with blot force 25 and plunged into liquid ethane.
Resolution 3.18 Å
9O53 Cryo-EM structure of the human SK2-4 chimera/calmodulin channel complex bound to a small molecule inhibitor Deposited 2025-04-09 Assembly 1 Insufficient information Heteromer；Protein × 8 PDB declaration: octameric（8） Consistent with protein count
Chain A 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Chain B 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Chain C 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Chain D 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Not recorded A1B8D N-(2,1,3-benzoxadiazol-4-yl)-3-(4-methoxybenzene-1-sulfonamido)benzamide × 4 K POTASSIUM ION × 4 CA CALCIUM ION × 16 ELECTRON MICROSCOPY
cryo-EM buffer pH 8；20 mM Tris pH 8, 150 mM KCl, 2 mM CaCl2, 0.005% GDN, 0.0005% CHS
cryo-EM vitrification conditions Cryogen ETHANE；5 uL of sample was applied to grids at 4 degree temperature with 100% humidity. After 30 seconds, grids were blotted for 5 seconds with blot force 25 and plunged into liquid ethane.
Resolution 3.30 Å
9O5O Cryo-EM structure of the human SK2-4 chimera/calmodulin channel complex bound to a small molecule activator Deposited 2025-04-10 Assembly 1 Insufficient information Heteromer；Protein × 8 PDB declaration: octameric（8） Consistent with protein count
Chain A 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Chain B 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Chain C 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Chain D 124–412（289 aa） Fragment：SK4 residues 1-15 + SK2 residues 124-412 + SK4 residues 306-428
Not recorded A1B8G N-(2,1,3-benzoxadiazol-4-yl)-4-(trifluoromethyl)benzamide × 4 K POTASSIUM ION × 2 CA CALCIUM ION × 16 ELECTRON MICROSCOPY
cryo-EM buffer pH 8；20 mM Tris pH 8, 150 mM KCl, 2 mM CaCl2, 0.005% GDN, 0.0005% CHS
cryo-EM vitrification conditions Cryogen ETHANE；5 uL of sample was applied to grids at 4 degree temperature with 100% humidity. After 30 seconds, grids were blotted for 5 seconds with blot force 25 and plunged into liquid ethane.
Resolution 3.10 Å
9VU9 channel D complex with 4 Deposited 2025-07-12 Assembly 1 Protein heterocomplex Heteromer；Protein × 7 PDB declaration: heptameric（7） Consistent with protein count
Chain A 1–579（579 aa）
Chain B 1–579（579 aa）
Chain C 1–579（579 aa）
Chain D 1–579（579 aa）
Not recorded A1ETX (3~{S})-3-(1~{H}-benzimidazol-2-ylamino)-~{N}-(cyanomethyl)-~{N}-methyl-3-[3-(trifluoromethyl)phenyl]propanamide × 1 K POTASSIUM ION × 4 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.34 Å
9VUA channel A complex with 1 Deposited 2025-07-12 Assembly 1 Protein heterocomplex Heteromer；Protein × 8 PDB declaration: octameric（8） Consistent with protein count
Chain A 1–579（579 aa）
Chain B 1–579（579 aa）
Chain C 1–579（579 aa）
Chain D 1–579（579 aa）
Not recorded K POTASSIUM ION × 4 POV (2S)-3-(hexadecanoyloxy)-2-[(9Z)-octadec-9-enoyloxy]propyl 2-(trimethylammonio)ethyl phosphate × 4 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.23 Å
9VUB channel C complex with 3 Deposited 2025-07-12 Assembly 1 Protein heterocomplex Heteromer；Protein × 8 PDB declaration: octameric（8） Consistent with protein count
Chain A 1–579（579 aa）
Chain B 1–579（579 aa）
Chain C 1–579（579 aa）
Chain D 1–579（579 aa）
Not recorded POV (2S)-3-(hexadecanoyloxy)-2-[(9Z)-octadec-9-enoyloxy]propyl 2-(trimethylammonio)ethyl phosphate × 32 CLR CHOLESTEROL × 8 CA CALCIUM ION × 12 A1B92 Rimtuzalcap × 4 K POTASSIUM ION × 3 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.35 Å
9VUC channel B complex with 2 Deposited 2025-07-12 Assembly 1 Protein heterocomplex Heteromer；Protein × 7 PDB declaration: heptameric（7） Consistent with protein count
Chain A 1–579（579 aa）
Chain B 1–579（579 aa）
Chain C 1–579（579 aa）
Chain D 1–579（579 aa）
Not recorded K POTASSIUM ION × 4 Y7Z UCL1684 × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 2.96 Å
9ZRQ Cryo-EM structure of KCa2.2/calmodulin channel in complex with SKA31. Deposited 2025-12-20 Assembly 1 Protein heterocomplex Heteromer；Protein × 8 PDB declaration: octameric（8） Consistent with protein count
Chain A 117–477（361 aa）
Chain B 117–477（361 aa）
Chain C 117–477（361 aa）
Chain D 117–477（361 aa）
Not recorded K POTASSIUM ION × 4 A1C3Q naphtho[1,2-d][1,3]thiazol-2-amine × 4 CA CALCIUM ION × 8 ELECTRON MICROSCOPY
cryo-EM buffer pH 8
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 2.77 Å
9ZRR Cryo-EM structure of KCa2.2/calmodulin channel in complex with SKA111. Deposited 2025-12-20 Assembly 1 Protein heterocomplex Heteromer；Protein × 8 PDB declaration: octameric（8） Consistent with protein count
Chain A 117–477（361 aa）
Chain B 117–477（361 aa）
Chain C 117–477（361 aa）
Chain D 117–477（361 aa）
Not recorded K POTASSIUM ION × 2 A1C3U 5-methylnaphtho[1,2-d][1,3]thiazol-2-amine × 4 CA CALCIUM ION × 12 ELECTRON MICROSCOPY
cryo-EM buffer pH 8
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.31 Å

This page presents structural evidence recorded in PDB/mmCIF.“No recorded non-water small molecule” does not prove that the experimental sample was ligand-free; experimental conditions belong to the PDB experiment, while ligands and copy counts are shown for each biological assembly.