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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：P09871 New Search
14PDB entries
25Biological assembly
33chain/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
1ELV CRYSTAL STRUCTURE OF THE CATALYTIC DOMAIN OF HUMAN COMPLEMENT C1S PROTEASE Deposited 2000-03-14 Assembly 1 Other combination Monomer；Protein × 1 PDB declaration: monomeric（1） Consistent with protein count
Chain A 358–688（331 aa） Fragment：CCP2-SP CATALYTIC FRAGMENT: ASP363-ASP-673 SEGMENT PRECEDED BY AN ASP-LEU SEQUENCE ADDED AT THE N-TERMINAL END
Mutation：YES SO4 SULFATE ION × 2 NES 2-(2-HYDROXY-1,1-DIHYDROXYMETHYL-ETHYLAMINO)-ETHANESULFONIC ACID × 1 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 7.4；277 K；PEG 4K 34%, AMMONIUM SULFATE 100mM, pH 7.4, VAPOR DIFFUSION, HANGING DROP, temperature 277K
Resolution 1.70 Å R-free 0.219
1NZI Crystal Structure of the CUB1-EGF Interaction Domain of Complement Protease C1s Deposited 2003-02-18 Assembly 1 Protein homooligomer Homooligomer；Protein × 2 PDB declaration: dimeric（2） Consistent with protein count
Chain A 16–174（159 aa） Fragment：CALCIUM-DEPENDENT INTERACTION DOMAIN
Chain B 16–174（159 aa） Fragment：CALCIUM-DEPENDENT INTERACTION DOMAIN
Not recorded CA CALCIUM ION × 2 MG MAGNESIUM ION × 2 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 7.5；293 K；PEG 4000, magnesium chloride, glycerol, pH 7.5, VAPOR DIFFUSION, HANGING DROP, temperature 293K
Resolution 1.50 Å R-free 0.234
4J1Y The X-ray crystal structure of human complement protease C1s zymogen Deposited 2013-02-03 Assembly 1 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric（1） Consistent with protein count
Chain A 292–688（397 aa） Fragment：CCP1-CCP2-SPz (UNP Residues 292-698)
Mutation：Q436A, I438A No recorded non-water small molecule X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 7.4；293 K；18% PEG 3350, 0.2M potassium nitrate., pH 7.4, VAPOR DIFFUSION, HANGING DROP, temperature 293K
Resolution 2.66 Å R-free 0.259
4J1Y The X-ray crystal structure of human complement protease C1s zymogen Deposited 2013-02-03 Assembly 2 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric（1） Consistent with protein count
Chain B 292–688（397 aa） Fragment：CCP1-CCP2-SPz (UNP Residues 292-698)
Mutation：Q436A, I438A No recorded non-water small molecule X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 7.4；293 K；18% PEG 3350, 0.2M potassium nitrate., pH 7.4, VAPOR DIFFUSION, HANGING DROP, temperature 293K
Resolution 2.66 Å R-free 0.259
4J1Y The X-ray crystal structure of human complement protease C1s zymogen Deposited 2013-02-03 Assembly 3 Protein homooligomer Homooligomer；Protein × 2 PDB declaration: dimeric（2） Consistent with protein count
Chain A 292–688（397 aa） Fragment：CCP1-CCP2-SPz (UNP Residues 292-698)
Chain B 292–688（397 aa） Fragment：CCP1-CCP2-SPz (UNP Residues 292-698)
Mutation：Q436A, I438A Mutation：Q436A, I438A No recorded non-water small molecule X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 7.4；293 K；18% PEG 3350, 0.2M potassium nitrate., pH 7.4, VAPOR DIFFUSION, HANGING DROP, temperature 293K
Resolution 2.66 Å R-free 0.259
4LMF C1s CUB1-EGF-CUB2 Deposited 2013-07-10 Assembly 1 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric（1） Consistent with protein count
Chain A 17–292（276 aa） Fragment：CUB1-EGF-CUB2 fragment (unp residues 17-292)
Not recorded NA SODIUM ION × 1 CA CALCIUM ION × 3 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 8.5；298 K；pH 8.5, VAPOR DIFFUSION, SITTING DROP, temperature 298K
Resolution 2.92 Å R-free 0.252
4LMF C1s CUB1-EGF-CUB2 Deposited 2013-07-10 Assembly 2 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric（1） Consistent with protein count
Chain B 17–292（276 aa） Fragment：CUB1-EGF-CUB2 fragment (unp residues 17-292)
Not recorded NA SODIUM ION × 1 CA CALCIUM ION × 3 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 8.5；298 K；pH 8.5, VAPOR DIFFUSION, SITTING DROP, temperature 298K
Resolution 2.92 Å R-free 0.252
4LMF C1s CUB1-EGF-CUB2 Deposited 2013-07-10 Assembly 3 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric（1） Consistent with protein count
Chain C 17–292（276 aa） Fragment：CUB1-EGF-CUB2 fragment (unp residues 17-292)
Not recorded NA SODIUM ION × 1 CA CALCIUM ION × 3 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 8.5；298 K；pH 8.5, VAPOR DIFFUSION, SITTING DROP, temperature 298K
Resolution 2.92 Å R-free 0.252
4LMF C1s CUB1-EGF-CUB2 Deposited 2013-07-10 Assembly 4 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric（1） Consistent with protein count
Chain D 17–292（276 aa） Fragment：CUB1-EGF-CUB2 fragment (unp residues 17-292)
Not recorded NA SODIUM ION × 1 CA CALCIUM ION × 3 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 8.5；298 K；pH 8.5, VAPOR DIFFUSION, SITTING DROP, temperature 298K
Resolution 2.92 Å R-free 0.252
4LMF C1s CUB1-EGF-CUB2 Deposited 2013-07-10 Assembly 5 Protein homooligomer Homooligomer；Protein × 2 PDB declaration: dimeric（2） Consistent with protein count
Chain A 17–292（276 aa） Fragment：CUB1-EGF-CUB2 fragment (unp residues 17-292)
Chain D 17–292（276 aa） Fragment：CUB1-EGF-CUB2 fragment (unp residues 17-292)
Not recorded NA SODIUM ION × 2 CA CALCIUM ION × 6 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 8.5；298 K；pH 8.5, VAPOR DIFFUSION, SITTING DROP, temperature 298K
Resolution 2.92 Å R-free 0.252
4LMF C1s CUB1-EGF-CUB2 Deposited 2013-07-10 Assembly 6 Protein homooligomer Homooligomer；Protein × 2 PDB declaration: dimeric（2） Consistent with protein count
Chain B 17–292（276 aa） Fragment：CUB1-EGF-CUB2 fragment (unp residues 17-292)
Chain C 17–292（276 aa） Fragment：CUB1-EGF-CUB2 fragment (unp residues 17-292)
Not recorded NA SODIUM ION × 2 CA CALCIUM ION × 6 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 8.5；298 K；pH 8.5, VAPOR DIFFUSION, SITTING DROP, temperature 298K
Resolution 2.92 Å R-free 0.252
4LOR C1s CUB1-EGF-CUB2 in complex with a collagen-like peptide from C1q Deposited 2013-07-13 Assembly 1 Protein heterocomplex Heteromer；Protein × 4 PDB declaration: tetrameric（4） Consistent with protein count
Chain A 17–292（276 aa） Fragment：CUB1-EGF-CUB2 fragment (unp residues 17-292)
Not recorded CA CALCIUM ION × 3 NA SODIUM ION × 2 NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 1 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 8.5；293 K；100 mM Tris, 100 mM NaBr, 24% PEG 3350 , pH 8.5, VAPOR DIFFUSION, SITTING DROP, temperature 293K
Resolution 2.50 Å R-free 0.252
4LOS C1s CUB2-CCP1 Deposited 2013-07-13 Assembly 1 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric（1） Consistent with protein count
Chain A 172–358（187 aa） Fragment：CUB2-CCP1 fragment (unp residues 172-358)
Not recorded CA CALCIUM ION × 1 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 8；293 K；100 mM Tris/acetate, 200 mM KH2PO4 + 20% PEG 10K , pH 8, VAPOR DIFFUSION, SITTING DROP, temperature 293K
Resolution 2.00 Å R-free 0.212
4LOT C1s CUB2-CCP1-CCP2 Deposited 2013-07-13 Assembly 1 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric（1） Consistent with protein count
Chain A 175–423（249 aa） Fragment：CUB2-CCP1-CCP2 fragment (unp residues 175-423)
Not recorded No recorded non-water small molecule X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 6.3；293 K；24% PEG 8K in Bis-tris propane-HCL, containing 200 mM potassium citrate, pH 6.3, VAPOR DIFFUSION, SITTING DROP, temperature 293K
Resolution 2.92 Å R-free 0.292
5UBM Crystal structure of human C1s in complex with inhibitor gigastasin Deposited 2016-12-20 Assembly 1 Other combination Heteromer；Protein × 3 PDB declaration: trimeric（3） Consistent with protein count
Chain A 437–688（252 aa）
Chain B 285–436（152 aa）
Not recorded No recorded non-water small molecule X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 5.5；277 K；0.1 M Bis-Tris, pH 5.5, 25 % PEG 3350
Resolution 2.50 Å R-free 0.222
6F1C C1rC1s complex Deposited 2017-11-21 Assembly 1 Other combination Heteromer；Protein × 4 PDB declaration: tetrameric（4） Consistent with protein count
Chain B 16–292（277 aa）
Chain D 16–292（277 aa）
Not recorded CA CALCIUM ION × 12 NA SODIUM ION × 6 NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 2 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 8；293 K；12-18% PEG 8000, 100 mM Imidazole at pH 8.0
Resolution 4.20 Å R-free 0.305
6F1H C1rC1s complex Deposited 2017-11-22 Assembly 1 Other combination Heteromer；Protein × 2 PDB declaration: dimeric（2） Consistent with protein count
Chain B 17–292（276 aa）
Not recorded CA CALCIUM ION × 6 NA SODIUM ION × 3 NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 1 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 8；298 K；12-18% PEG 8000, 100 mM Imidazole at pH 8.0
Resolution 4.50 Å R-free 0.340
6F1H C1rC1s complex Deposited 2017-11-22 Assembly 2 Other combination Heteromer；Protein × 2 PDB declaration: dimeric（2） Consistent with protein count
Chain D 17–292（276 aa）
Not recorded CA CALCIUM ION × 6 NA SODIUM ION × 3 LYS LYSINE × 1 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 8；298 K；12-18% PEG 8000, 100 mM Imidazole at pH 8.0
Resolution 4.50 Å R-free 0.340
8GMN Crystal structure of human C1s in complex with inhibitor Deposited 2023-03-26 Assembly 1 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric（1） Consistent with protein count
Chain A 358–688（331 aa）
Not recorded ZWK [4-(1-aminophthalazin-6-yl)piperazin-1-yl](2-methylphenyl)methanone × 1 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；277 K；22% PEG 3350, 50-100 mM Ammonium Sulphate and 100 mM TRIS pH 7.5-8.0
Resolution 2.60 Å R-free 0.281
8GMN Crystal structure of human C1s in complex with inhibitor Deposited 2023-03-26 Assembly 2 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric（1） Consistent with protein count
Chain B 358–688（331 aa）
Not recorded ZWK [4-(1-aminophthalazin-6-yl)piperazin-1-yl](2-methylphenyl)methanone × 1 SO4 SULFATE ION × 1 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；277 K；22% PEG 3350, 50-100 mM Ammonium Sulphate and 100 mM TRIS pH 7.5-8.0
Resolution 2.60 Å R-free 0.281
8GMN Crystal structure of human C1s in complex with inhibitor Deposited 2023-03-26 Assembly 3 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric（1） Consistent with protein count
Chain C 358–688（331 aa）
Not recorded ZWK [4-(1-aminophthalazin-6-yl)piperazin-1-yl](2-methylphenyl)methanone × 1 SO4 SULFATE ION × 1 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；277 K；22% PEG 3350, 50-100 mM Ammonium Sulphate and 100 mM TRIS pH 7.5-8.0
Resolution 2.60 Å R-free 0.281
8GMN Crystal structure of human C1s in complex with inhibitor Deposited 2023-03-26 Assembly 4 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric（1） Consistent with protein count
Chain D 358–688（331 aa）
Not recorded ZWK [4-(1-aminophthalazin-6-yl)piperazin-1-yl](2-methylphenyl)methanone × 1 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；277 K；22% PEG 3350, 50-100 mM Ammonium Sulphate and 100 mM TRIS pH 7.5-8.0
Resolution 2.60 Å R-free 0.281
8TYP Complement Protease C1s Inhibited by 6-(4-phenylpiperazin-1-yl)pyridine-3-carboximidamide Deposited 2023-08-25 Assembly 1 Other combination Monomer；Protein × 1 PDB declaration: monomeric（1） Consistent with protein count
Chain A 358–688（331 aa）
Not recorded SQT 6-(4-phenylpiperazin-1-yl)pyridine-3-carboximidamide × 1 X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；293 K；0.2 M sodium acetate 0.1 M Tris-HCl (pH 8.1) PEG-4000 24% (w/v)
Resolution 1.80 Å R-free 0.196
8W18 The crystal structure of the Michaelis-Menten complex of a C1s/C1-INH at 3.94 Angstroms Deposited 2024-02-15 Assembly 1 Protein heterocomplex Heteromer；Protein × 3 PDB declaration: trimeric（3） Consistent with protein count
Chain A 292–437（146 aa） Fragment：Sushi domains
Chain B 438–688（251 aa）
Mutation：S632A No recorded non-water small molecule X-RAY DIFFRACTION
X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；295 K；0.1 M L-Proline, 0.1M HEPES (pH 6.5), and 12% PEG 3,350
Resolution 3.94 Å R-free 0.281
9X1H Cryo-EM Structure of human complement C1s CUB domain in complex with RAY121 Deposited 2025-10-02 Assembly 1 Protein heterocomplex Heteromer；Protein × 6 PDB declaration: hexameric（6） Consistent with protein count
Chain A 16–292（277 aa）
Chain B 16–292（277 aa）
Not recorded CA CALCIUM ION × 4 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5；20mM HEPES(7.5), 150mM NaCl, 3mM CaCl2, 0.03% DDM
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 2.60 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.