9zfo

Cryo-EM Structure of Human STAT2-USP18-ISG15 Complex

Method: ELECTRON MICROSCOPY D_max: 126.5 Å Quality: GOOD

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1. Protein Identity and Related Structures Protein Identity & Related Structures

Ubl carboxyl-terminal hydrolase 18

Homo sapiens

State in the Current Structure

Assembly	Oligomeric State	Construct	Mutations and Modifications	Ligands, Ions and Associated Components	Method and Experimental Conditions	Structure Quality
1	Protein heterocomplex Heteromer Protein × 3 PDB declaration: trimeric（3） Consistent with protein copy count	Chain U； UniProt 26–372	Not recorded	Signal transducer and activator of transcription 2 × 1 （P52630） Ubiquitin-like protein ISG15 × 1 （P05161）	ELECTRON MICROSCOPY cryo-EM buffer：pH 8；25mM HEPES (pH 8.0), 200mM NaCl and 1.0mM TCEP cryo-EM vitrification conditions：Cryogen ETHANE	Resolution 3.05 Å

Other States of the Same Protein in the Database

Each row is a biological assembly of the same UniProt protein in another PDB entry. The “Difference from current entry” column identifies evidence-level differences; no tag means the currently parsed fields agree.

Other PDB	Difference from Current Entry 9ZFO	Assembly / Oligomeric State	Construct	Mutations and Modifications	Ligands, Ions and Non-polymers	Method and Experimental Conditions	Structure Quality
9QY8 Crystal structure of apoform human USP18 Deposited 2025-04-17	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Insufficient information Monomer；Protein × 1 PDB declaration: monomeric	Chain A 49–285（237 aa） Chain A 300–372（73 aa）	Not recorded	ZN ZINC ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；277 K；0.2 M sodium citrate tribasic dihydrate, 0.1 M Bis-Tris propane, pH 7.5, 20 % (w/v) PEG3350	Resolution 1.92 Å R-free 0.260
9QY8 Crystal structure of apoform human USP18 Deposited 2025-04-17	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 2 Insufficient information Monomer；Protein × 1 PDB declaration: monomeric	Chain B 49–285（237 aa） Chain B 300–372（73 aa）	Not recorded	ZN ZINC ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；277 K；0.2 M sodium citrate tribasic dihydrate, 0.1 M Bis-Tris propane, pH 7.5, 20 % (w/v) PEG3350	Resolution 1.92 Å R-free 0.260

1 other PDB entries and 2 assemblies. Open the comparison page and filter oligomeric states

View Construct and Data Evidence

UniProt name	UBP18_HUMAN
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain U； PDBConstruct 1–347； UniProt 26–372

Signal transducer and activator of transcription 2

Homo sapiens

UniProt P52630

State in the Current Structure

Assembly	Oligomeric State	Construct	Mutations and Modifications	Ligands, Ions and Associated Components	Method and Experimental Conditions	Structure Quality
1	Protein heterocomplex Heteromer Protein × 3 PDB declaration: trimeric（3） Consistent with protein copy count	Chain S； UniProt 1–713	Not recorded	Ubl carboxyl-terminal hydrolase 18 × 1 （Q9UMW8） Ubiquitin-like protein ISG15 × 1 （P05161）	ELECTRON MICROSCOPY cryo-EM buffer：pH 8；25mM HEPES (pH 8.0), 200mM NaCl and 1.0mM TCEP cryo-EM vitrification conditions：Cryogen ETHANE	Resolution 3.05 Å

Other States of the Same Protein in the Database

Other PDB	Difference from Current Entry 9ZFO	Assembly / Oligomeric State	Construct	Mutations and Modifications	Ligands, Ions and Non-polymers	Method and Experimental Conditions	Structure Quality
2KA4 NMR structure of the CBP-TAZ1/STAT2-TAD complex Deposited 2008-10-30	Different construct Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain B 786–838（53 aa） Fragment：UNP residues 786 to 838	Not recorded	ZN ZINC ION × 3	SOLUTION NMR NMR measurement conditions pH 6.8；305 K；Ionic strength (raw mmCIF value) 0.05；Pressure ambient NMR sample composition 1 mM [U-100% 15N] ALANINE, 93% H2O/7% D2O \| 93% H2O/7% D2O	Resolution not provided
6UX2 Crystal structure of ZIKV RdRp in complex with STAT2 Deposited 2019-11-06	Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain A 1–713（713 aa）	Not recorded	SO4 SULFATE ION × 4 ZN ZINC ION × 2	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 8.5；298.15 K；0.2 M ammonium sulfate, 11% PEG 8000 and 0.1 M Tris-HCl, pH 8.5	Resolution 3.01 Å R-free 0.264
6WCZ CryoEM structure of full-length ZIKV NS5-hSTAT2 complex Deposited 2020-03-31	Different construct Different oligomeric state Different ligand/ion Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain A 1–851（851 aa）	Not recorded	ZN ZINC ION × 2	ELECTRON MICROSCOPY cryo-EM buffer pH 7.5；25 mM Tris-HCl, pH 7.5, 175 mM NaCl, 5 mM DTT cryo-EM vitrification conditions Cryogen ETHANE	Resolution 4.00 Å
8T12 Cryo-EM structure of DENV2 NS5 in complex with human STAT2 with the N-terminal domain of STAT2 ordered. Deposited 2023-06-01	Different construct Different oligomeric state Different ligand/ion Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain A 1–851（851 aa）	Not recorded	ZN ZINC ION × 2	ELECTRON MICROSCOPY cryo-EM buffer pH 7.5 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.34 Å
8T13 Cryo-EM structure of DENV2 NS5 in complex with human STAT2 with the N-terminal domain of STAT2 disordered Deposited 2023-06-01	Different construct Different oligomeric state Different ligand/ion Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain A 1–851（851 aa）	Not recorded	ZN ZINC ION × 2	ELECTRON MICROSCOPY cryo-EM buffer pH 7.5 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.45 Å

5 other PDB entries and 5 assemblies. Open the comparison page and filter oligomeric states

View Construct and Data Evidence

UniProt name	STAT2_HUMAN
Isoform	—
PDB entities	2
Chains and sequence ranges	Author chain S； PDBConstruct 1–713； UniProt 1–713

Ubiquitin-like protein ISG15

Homo sapiens

UniProt P05161

State in the Current Structure

Assembly	Oligomeric State	Construct	Mutations and Modifications	Ligands, Ions and Associated Components	Method and Experimental Conditions	Structure Quality
1	Protein heterocomplex Heteromer Protein × 3 PDB declaration: trimeric（3） Consistent with protein copy count	Chain I； UniProt 1–157	Not recorded	Ubl carboxyl-terminal hydrolase 18 × 1 （Q9UMW8） Signal transducer and activator of transcription 2 × 1 （P52630）	ELECTRON MICROSCOPY cryo-EM buffer：pH 8；25mM HEPES (pH 8.0), 200mM NaCl and 1.0mM TCEP cryo-EM vitrification conditions：Cryogen ETHANE	Resolution 3.05 Å

Other States of the Same Protein in the Database

Other PDB	Difference from Current Entry 9ZFO	Assembly / Oligomeric State	Construct	Mutations and Modifications	Ligands, Ions and Non-polymers	Method and Experimental Conditions	Structure Quality
1Z2M Crystal Structure of ISG15, the Interferon-Induced Ubiquitin Cross Reactive Protein Deposited 2005-03-08	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric	Chain A 0–154（155 aa）	Mutation：c78s	OS4 OSMIUM 4+ ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 8；292 K；Tris-HCl buffer, PEG4K, MgCl2, pH 8.0, VAPOR DIFFUSION, HANGING DROP, temperature 292K	Resolution 2.50 Å R-free 0.223
2HJ8 Solution NMR structure of the C-terminal domain of the interferon alpha-inducible ISG15 protein from Homo sapiens. Northeast Structural Genomics target HR2873B Deposited 2006-06-30	Different construct Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric	Chain A 78–156（79 aa） Fragment：ISG15 C-terminal domain (8.9 kDa), Ubiquitin-like 2	Not recorded	No recorded non-water small molecule	SOLUTION NMR NMR measurement conditions pH 6.5；293 K；Ionic strength (raw mmCIF value) 50 mM ammonium citrate, 5 mM CaCl2；Pressure ambient NMR sample composition 0.81 mM U-13C,15N HR2873B, 50 mM ammonium citrate, 5 mM CaCl2, 1x protease inhibitor, 0.02% NaN3, pH 6.5, 5% D2O / 95% H2O \| 5% D2O / 95% H2O NMR sample composition 0.9 mM 5%-13C,U-15N HR2873B, 50 mM ammonium citrate, 5 mM CaCl2, 1x protease inhibitor, 0.02% NaN3, pH 6.5, 5% D2O / 95% H2O \| 5% D2O / 95% H2O	Resolution not provided
3PHX OTU Domain of Crimean Congo Hemorrhagic Fever Virus in complex with ISG15 Deposited 2010-11-04	Different construct Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain B 79–156（78 aa） Fragment：UNP residues 79-156	Not recorded	ZN ZINC ION × 12 ACY ACETIC ACID × 2 NEH ETHANAMINE × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 6.5；293 K；10% PEG8K, 0.2M zinc acetate, 0.1M MES sodium salt, pH 6.5, VAPOR DIFFUSION, HANGING DROP, temperature 293K	Resolution 1.60 Å R-free 0.192
3PHX OTU Domain of Crimean Congo Hemorrhagic Fever Virus in complex with ISG15 Deposited 2010-11-04	Different construct Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 2 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain B 79–156（78 aa） Fragment：UNP residues 79-156	Not recorded	ZN ZINC ION × 12 ACY ACETIC ACID × 2 NEH ETHANAMINE × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 6.5；293 K；10% PEG8K, 0.2M zinc acetate, 0.1M MES sodium salt, pH 6.5, VAPOR DIFFUSION, HANGING DROP, temperature 293K	Resolution 1.60 Å R-free 0.192
3PSE Structure of a viral OTU domain protease bound to interferon-stimulated gene 15 (ISG15) Deposited 2010-12-01	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain B 1–156（156 aa）	Mutation：C78S	4LJ 1.7.6 3-bromanylpropan-1-amine × 1 GOL GLYCEROL × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 6.4；293 K；100 mM MES, 23% PEG6000, pH 6.4, VAPOR DIFFUSION, HANGING DROP, temperature 293K	Resolution 2.30 Å R-free 0.224
3R66 Crystal structure of human ISG15 in complex with NS1 N-terminal region from influenza virus B, Northeast Structural Genomics Consortium Target IDs HX6481, HR2873, and OR2 Deposited 2011-03-21	Different construct Different mutation/modification Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 4 PDB declaration: tetrameric	Chain C 1–157（157 aa） Chain D 1–157（157 aa）	Non-standard monomer：Yes (specific site not provided by mmCIF) Non-standard monomer：Yes (specific site not provided by mmCIF)	No recorded non-water small molecule	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 7.5；293 K；15% PEG3350, 1% dioxane, pH 7.5, VAPOR DIFFUSION, HANGING DROP, temperature 293K	Resolution 2.30 Å R-free 0.265
3RT3 Complex of influenza virus protein with host anti-viral factor Deposited 2011-05-03	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 4 PDB declaration: tetrameric	Chain B 1–158（158 aa）	Mutation：C78S	SIN SUCCINIC ACID × 4	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；291 K；20% PEG 8000, 0.1M HEPES, pH 7.5, VAPOR DIFFUSION, SITTING DROP, temperature 291K	Resolution 2.01 Å R-free 0.243
3SDL Crystal structure of human ISG15 in complex with NS1 N-terminal region from influenza B virus, Northeast Structural Genomics Consortium Target IDs HX6481, HR2873, and OR2 Deposited 2011-06-09	Different construct Different mutation/modification Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 4 PDB declaration: tetrameric	Chain C 1–157（157 aa） Chain D 1–157（157 aa）	Not recorded	No recorded non-water small molecule	X-RAY DIFFRACTION X-ray crystallization conditions EVAPORATION；pH 7.5；293 K；15% PEG3350, 1% dioxane, pH 7.5, VAPOR DIFFUSION, HANGING DROP, temperature 293K, EVAPORATION	Resolution 2.29 Å R-free 0.261
5TL6 Crystal structure of SARS-CoV papain-like protease in complex with the C-terminal domain of human ISG15 Deposited 2016-10-10	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain A 80–157（78 aa） Fragment：C-terminal domain (UNP residues 80-157)	Non-standard monomer：Yes (specific site not provided by mmCIF)	ZN ZINC ION × 1 SO4 SULFATE ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 6.5；293 K；0.1 M lithium sulfate, 0.1 M Bis-tris [pH 6.5], 22% PEG 3350, supplemented with 30% (v/v) glycerol additive in a 1:5 dilution	Resolution 2.62 Å R-free 0.250
5TL6 Crystal structure of SARS-CoV papain-like protease in complex with the C-terminal domain of human ISG15 Deposited 2016-10-10	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 2 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain C 80–157（78 aa） Fragment：C-terminal domain (UNP residues 80-157)	Non-standard monomer：Yes (specific site not provided by mmCIF)	ZN ZINC ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 6.5；293 K；0.1 M lithium sulfate, 0.1 M Bis-tris [pH 6.5], 22% PEG 3350, supplemented with 30% (v/v) glycerol additive in a 1:5 dilution	Resolution 2.62 Å R-free 0.250
5W8T Crystal structure of MERS-CoV papain-like protease in complex with the C-terminal domain of human ISG15 Deposited 2017-06-22	Different construct Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain B 80–156（77 aa）	Not recorded	AYE prop-2-en-1-amine × 1 ZN ZINC ION × 5 MPD (4S)-2-METHYL-2,4-PENTANEDIOL × 2	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；293 K；200 mM CaCl2, 100 mM NaO2C2H3 pH 4.6, 28% (v/v) MPD	Resolution 2.76 Å R-free 0.224
5W8T Crystal structure of MERS-CoV papain-like protease in complex with the C-terminal domain of human ISG15 Deposited 2017-06-22	Different construct Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 2 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain D 80–156（77 aa）	Not recorded	AYE prop-2-en-1-amine × 1 ZN ZINC ION × 1 MPD (4S)-2-METHYL-2,4-PENTANEDIOL × 4	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；293 K；200 mM CaCl2, 100 mM NaO2C2H3 pH 4.6, 28% (v/v) MPD	Resolution 2.76 Å R-free 0.224
5W8U Crystal structure of MERS-CoV papain-like protease in complex with the C-terminal domain of human ISG15 Deposited 2017-06-22	Different construct Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain B 80–156（77 aa） Fragment：UNP residues 80-156	Not recorded	ZN ZINC ION × 3 AYE prop-2-en-1-amine × 1 MPD (4S)-2-METHYL-2,4-PENTANEDIOL × 4	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；293 K；200 mM CaCl2, 100 mM NaO2C2H3 pH 4.6, 28% (v/v) MPD	Resolution 2.41 Å R-free 0.237
5W8U Crystal structure of MERS-CoV papain-like protease in complex with the C-terminal domain of human ISG15 Deposited 2017-06-22	Different construct Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 2 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain D 80–156（77 aa） Fragment：UNP residues 80-156	Not recorded	ZN ZINC ION × 3 AYE prop-2-en-1-amine × 1 MPD (4S)-2-METHYL-2,4-PENTANEDIOL × 4	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；293 K；200 mM CaCl2, 100 mM NaO2C2H3 pH 4.6, 28% (v/v) MPD	Resolution 2.41 Å R-free 0.237
6BI8 X-ray structure of MERS coronavirus papain-like protease in complex with human ISG15 Deposited 2017-11-01	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain C 1–156（156 aa）	Mutation：C78S	PGE TRIETHYLENE GLYCOL × 2 ZN ZINC ION × 1 GOL GLYCEROL × 2 AYE prop-2-en-1-amine × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 8.3；293.15 K；0.25 M Potassium Citrate, pH 8.3 20% PEG3350	Resolution 2.29 Å R-free 0.215
6BI8 X-ray structure of MERS coronavirus papain-like protease in complex with human ISG15 Deposited 2017-11-01	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 2 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain D 1–156（156 aa）	Mutation：C78S	PGE TRIETHYLENE GLYCOL × 2 ZN ZINC ION × 1 GOL GLYCEROL × 3 AYE prop-2-en-1-amine × 1 CIT CITRIC ACID × 1 EDO 1,2-ETHANEDIOL × 2	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 8.3；293.15 K；0.25 M Potassium Citrate, pH 8.3 20% PEG3350	Resolution 2.29 Å R-free 0.215
6FFA FMDV Leader protease bound to substrate ISG15 Deposited 2018-01-05	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain B 79–155（77 aa）	Non-standard monomer：Yes (specific site not provided by mmCIF)	GOL GLYCEROL × 5 SO4 SULFATE ION × 3	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；291 K；2 M Ammonium Sulfate 0.2 M Sodium potassium tartrate tetrahydrate 0.1 M Sodium citrate tribasic (pH 5.6)	Resolution 1.50 Å R-free 0.186
6XA9 SARS CoV-2 PLpro in complex with ISG15 C-terminal domain propargylamide Deposited 2020-06-04	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain B 79–157（79 aa） Fragment：C-terminal domain (UNP residues 79-157)	Mutation：G176 replaced with propargylamide Non-standard monomer：Yes (specific site not provided by mmCIF)	GOL GLYCEROL × 3 ZN ZINC ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 6.5；293 K；0.2 M lithium sulfate, 25% PEG3350, 0.1 M Bis-Tris chloride, pH 6.5	Resolution 2.90 Å R-free 0.231
6XA9 SARS CoV-2 PLpro in complex with ISG15 C-terminal domain propargylamide Deposited 2020-06-04	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 2 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain D 79–157（79 aa） Fragment：C-terminal domain (UNP residues 79-157)	Mutation：G176 replaced with propargylamide Non-standard monomer：Yes (specific site not provided by mmCIF)	GOL GLYCEROL × 3 ZN ZINC ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 6.5；293 K；0.2 M lithium sulfate, 25% PEG3350, 0.1 M Bis-Tris chloride, pH 6.5	Resolution 2.90 Å R-free 0.231
6XA9 SARS CoV-2 PLpro in complex with ISG15 C-terminal domain propargylamide Deposited 2020-06-04	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 3 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain F 79–157（79 aa） Fragment：C-terminal domain (UNP residues 79-157)	Mutation：G176 replaced with propargylamide Non-standard monomer：Yes (specific site not provided by mmCIF)	GOL GLYCEROL × 2 ZN ZINC ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 6.5；293 K；0.2 M lithium sulfate, 25% PEG3350, 0.1 M Bis-Tris chloride, pH 6.5	Resolution 2.90 Å R-free 0.231
7RBS The crystal structure of Papain-Like Protease of SARS CoV-2, C111S mutant, in complex with human ISG15 Deposited 2021-07-06	Different construct Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain B 2–157（156 aa）	Not recorded	ZN ZINC ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；289 K；0.02 M MgCl2, 0.1 M HEPES buffer, 22% poly(acrylicacid sodium salt) 5100	Resolution 2.98 Å R-free 0.236
7RBS The crystal structure of Papain-Like Protease of SARS CoV-2, C111S mutant, in complex with human ISG15 Deposited 2021-07-06	Different construct Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 2 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain D 2–157（156 aa）	Not recorded	ZN ZINC ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；289 K；0.02 M MgCl2, 0.1 M HEPES buffer, 22% poly(acrylicacid sodium salt) 5100	Resolution 2.98 Å R-free 0.236
7RBS The crystal structure of Papain-Like Protease of SARS CoV-2, C111S mutant, in complex with human ISG15 Deposited 2021-07-06	Different construct Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 3 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain F 2–157（156 aa）	Not recorded	ZN ZINC ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；289 K；0.02 M MgCl2, 0.1 M HEPES buffer, 22% poly(acrylicacid sodium salt) 5100	Resolution 2.98 Å R-free 0.236
7RBS The crystal structure of Papain-Like Protease of SARS CoV-2, C111S mutant, in complex with human ISG15 Deposited 2021-07-06	Different construct Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 4 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain H 2–157（156 aa）	Not recorded	ZN ZINC ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；289 K；0.02 M MgCl2, 0.1 M HEPES buffer, 22% poly(acrylicacid sodium salt) 5100	Resolution 2.98 Å R-free 0.236
7RBS The crystal structure of Papain-Like Protease of SARS CoV-2, C111S mutant, in complex with human ISG15 Deposited 2021-07-06	Different construct Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 5 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain J 2–157（156 aa）	Not recorded	ZN ZINC ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；289 K；0.02 M MgCl2, 0.1 M HEPES buffer, 22% poly(acrylicacid sodium salt) 5100	Resolution 2.98 Å R-free 0.236
7S6P The crystal structure of human ISG15 Deposited 2021-09-14	Different construct Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric	Chain A 2–157（156 aa）	Not recorded	No recorded non-water small molecule	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；289 K；0.04 M potassium phosphate, 16% PEG8000, 20% glycerol	Resolution 2.15 Å R-free 0.268
7S6P The crystal structure of human ISG15 Deposited 2021-09-14	Different construct Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 2 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric	Chain B 2–157（156 aa）	Not recorded	No recorded non-water small molecule	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；289 K；0.04 M potassium phosphate, 16% PEG8000, 20% glycerol	Resolution 2.15 Å R-free 0.268
7S6P The crystal structure of human ISG15 Deposited 2021-09-14	Different construct Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 3 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric	Chain C 2–157（156 aa）	Not recorded	No recorded non-water small molecule	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；289 K；0.04 M potassium phosphate, 16% PEG8000, 20% glycerol	Resolution 2.15 Å R-free 0.268
7S6P The crystal structure of human ISG15 Deposited 2021-09-14	Different construct Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 4 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric	Chain D 2–157（156 aa）	Not recorded	No recorded non-water small molecule	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；289 K；0.04 M potassium phosphate, 16% PEG8000, 20% glycerol	Resolution 2.15 Å R-free 0.268
7S6P The crystal structure of human ISG15 Deposited 2021-09-14	Different construct Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 5 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric	Chain E 2–157（156 aa）	Not recorded	No recorded non-water small molecule	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；289 K；0.04 M potassium phosphate, 16% PEG8000, 20% glycerol	Resolution 2.15 Å R-free 0.268
7S6P The crystal structure of human ISG15 Deposited 2021-09-14	Different construct Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 6 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric	Chain F 2–157（156 aa）	Not recorded	No recorded non-water small molecule	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 7.5；289 K；0.04 M potassium phosphate, 16% PEG8000, 20% glycerol	Resolution 2.15 Å R-free 0.268
8OIF Structure of the UBE1L activating enzyme bound to ISG15 and UBE2L6 Deposited 2023-03-22	Different ligand/ion Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 3 PDB declaration: trimeric	Chain I 1–157（157 aa）	Not recorded	AMP ADENOSINE MONOPHOSPHATE × 1	ELECTRON MICROSCOPY cryo-EM buffer pH 8 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.50 Å
8SE9 Cryo-EM structure of a double loaded human UBA7-UBE2L6-ISG15 thioester mimetic complex (Form 2) Deposited 2023-04-08	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 4 PDB declaration: tetrameric	Chain B 1–157（157 aa） Chain D 1–157（157 aa）	Mutation：C78S Mutation：C78S	AMP ADENOSINE MONOPHOSPHATE × 1	ELECTRON MICROSCOPY cryo-EM buffer pH 7.5 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.20 Å
8SEA Cryo-EM structure of a double loaded human UBA7-UBE2L6-ISG15 thioester mimetic complex (Form 1) Deposited 2023-04-08	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 4 PDB declaration: tetrameric	Chain B 1–157（157 aa） Chain D 1–157（157 aa）	Mutation：C78S Mutation：C78S	AMP ADENOSINE MONOPHOSPHATE × 1	ELECTRON MICROSCOPY cryo-EM buffer pH 7.5 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.40 Å
8SEB Cryo-EM structure of a single loaded human UBA7-UBE2L6-ISG15 adenylate complex Deposited 2023-04-08	Different mutation/modification Different ligand/ion Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 3 PDB declaration: trimeric	Chain B 1–157（157 aa）	Mutation：C78S	AMP ADENOSINE MONOPHOSPHATE × 1	ELECTRON MICROSCOPY cryo-EM buffer pH 7.5 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.24 Å
8SV8 Cryo-EM structure of a double loaded human UBA7-UBE2L6-ISG15 thioester mimetic complex from a composite map Deposited 2023-05-15	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 4 PDB declaration: tetrameric	Chain B 1–157（157 aa） Chain D 1–157（157 aa）	Mutation：C78S Mutation：C78S	AMP ADENOSINE MONOPHOSPHATE × 1	ELECTRON MICROSCOPY cryo-EM buffer pH 7.5 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.38 Å
9NN9 ISG15 complexed with nanobody Deposited 2025-03-05	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain A 1–157（157 aa） Fragment：residues 1-157	Mutation：C78S	EDO 1,2-ETHANEDIOL × 1 SO4 SULFATE ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；292 K；25 % PEG 3350, 0.1 M trisodium citrate pH 5.6, 0.2 M ammonium sulfate	Resolution 2.59 Å R-free 0.244
9NN9 ISG15 complexed with nanobody Deposited 2025-03-05	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 2 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain C 1–157（157 aa） Fragment：residues 1-157	Mutation：C78S	EDO 1,2-ETHANEDIOL × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；292 K；25 % PEG 3350, 0.1 M trisodium citrate pH 5.6, 0.2 M ammonium sulfate	Resolution 2.59 Å R-free 0.244
9NN9 ISG15 complexed with nanobody Deposited 2025-03-05	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 3 Protein heterocomplex Heteromer；Protein × 2 PDB declaration: dimeric	Chain E 1–157（157 aa） Fragment：residues 1-157	Mutation：C78S	EDO 1,2-ETHANEDIOL × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；292 K；25 % PEG 3350, 0.1 M trisodium citrate pH 5.6, 0.2 M ammonium sulfate	Resolution 2.59 Å R-free 0.244

21 other PDB entries and 39 assemblies. Open the comparison page and filter oligomeric states

View Construct and Data Evidence

UniProt name	ISG15_HUMAN
Isoform	—
PDB entities	3
Chains and sequence ranges	Author chain I； PDBConstruct 1–157； UniProt 1–157

The page prioritizes protein identity, the current assembly, associated components, oligomeric state and cross-PDB links. Chain mapping and sequence ranges are retained as data evidence. Internal IDs, import timestamps and assembly operation expressions are maintenance fields and are not shown here.

SAXS scattering curve SAXS Profile

P(r) Distance Distribution P(r) Distribution

Download Download SAXS (.dat) P(r) (.pr.out) CIF

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2. Structure Basics 2. Structure Basics

Entry ID entry_id	9zfo
Deposition date deposition_date	2025-12-01
Structure title title	Cryo-EM Structure of Human STAT2-USP18-ISG15 Complex
Keywords keywords	Deubiquitinating Enzyme, ISGylation, Transcription Factor, SIGNALING PROTEIN; SIGNALING PROTEIN
Experimental Method method	ELECTRON MICROSCOPY

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3. SAXS Parameters (CRYSOL theoretical calculation) 3. SAXS Parameters (CRYSOL)

Radius of gyration Rg (Guinier) rg_guinier	37.37 Å
Radius of gyration Rg (electron density) rg_electron	37.11 Å
Forward intensity I(0) i0	128793000.00
Molecular weight molecular_weight	94272.0 kDa
Excluded volume excluded_volume	119310 Å³
Envelope volume envelope_volume	163970 Å³
Hydration-shell volume shell_volume	37765 Å³
Envelope diameter envelope_diameter	126.4 Å
Shell Rg shell_rg	41.82 Å
Envelope Rg envelope_rg	37.11 Å
Shape Rg shape_rg	37.08 Å
Total Rg total_rg	37.54 Å
Total atoms total_atoms	6635
Residues n_residues	827
Spherical-harmonic order n_harmonics	20
q range q_range	— – 0.5000 Å⁻¹
Data points n_points	101
Shell type shell_type	directional
Solvent electron density solvent_density	0.3340 e/Å³
Shell contrast contrast_shell	0.0300 e/Å³
CRYSOL version crysol_version	4.1.3

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4. P(r) Distance Distribution (GNOM inversion) 4. P(r) Analysis (GNOM)

Maximum dimension Dmax dmax	126.5 Å
Rg (real space) rg_real	37.66 Å
Rg uncertainty (real space) rg_real_error	0.99 Å
I(0) (real space) i0_real	1.2880e+08
I(0) uncertainty (real space) i0_real_error	1.8440e+06
Rg (reciprocal space) rg_reciprocal	37.49 Å
I(0) (reciprocal space) i0_reciprocal	128800000.0000
Solution quality estimate total_estimate	0.8435
Solution quality rating solution_quality	GOOD a GOOD solution
P(r) peaks n_peaks	1
Primary peak position r_peak_primary	30.1 Å
Skewness Skewness skewness	0.426
Kurtosis Kurtosis kurtosis	-0.565
Angular range angular_range	— – 0.2100 Å⁻¹
Current regularization parameter α current_alpha	0.0000
Highest regularization parameter α highest_alpha	38740000.0000
Real-space data points n_real_points	43
GNOM version gnom_version	4.1.3
Quality Criteria quality_criteria	AN1: 0.000; Oscil: 0.790; Stabil: 1.000; Sysdev: 1.000; Positv: 1.000; Valcen: 0.829; Smooth: 0.762

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5. Crystallography and Experiment 5. Crystallography & Experiment

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6. Entities and Polymers Entities & Polymers (3)

Entity 1 Entity 1 polymer

Description description	Ubl carboxyl-terminal hydrolase 18
Molecular weight formula_weight	40401.7 kDa
EC 编号 ec_number	3.4.19.12
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	U
Atom count atom_count	6635

LEEKKEEDSNMKREQPRERPRAWDYPHGLVGLHNIGQTCCLNSLIQVFVMNVDFTRILKRITVPRGADEQRRSVPFQMLLLLEKMQDSRQKAVRPLELAYCLQKCNVPLFVQHDAAQLYLKLWNLIKDQITDVHLVERLQALYTIRVKDSLICVDCAMESSRNSSMLTLPLSLFDVDSKPLKTLEDALHCFFQPRELSSKSKCFCENCGKKTRGKQVLKLTHLPQTLTIHLMRFSIRNSQTRKICHSLYFPQSLDFSQILPMKRESCDAEEQSGGQYELFAVIAHVGMADSGHYCVYIRNAVDGKWFCFNDSNICLVSWEDIQCTYGNPNYHWQETAYLLVYMKMEC

来源 Source

来源生物 organism	Homo sapiens
通用名 common_name	human
NCBI Class编号 ncbi_taxonomy_id	9606
宿主生物 host_organism	Spodoptera frugiperda

Entity 2 Entity 2 polymer

Description description	Signal transducer and activator of transcription 2
Molecular weight formula_weight	82825.8 kDa
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	S

MAQWEMLQNLDSPFQDQLHQLYSHSLLPVDIRQYLAVWIEDQNWQEAALGSDDSKATMLFFHFLDQLNYECGRCSQDPESLLLQHNLRKFCRDIQPFSQDPTQLAEMIFNLLLEEKRILIQAQRAQLEQGEPVLETPVESQQHEIESRILDLRAMMEKLVKSISQLKDQQDVFCFRYKIQAKGKTPSLDPHQTKEQKILQETLNELDKRRKEVLDASKALLGRLTTLIELLLPKLEEWKAQQQKACIRAPIDHGLEQLETWFTAGAKLLFHLRQLLKELKGLSCLVSYQDDPLTKGVDLRNAQVTELLQRLLHRAFVVETQPCMPQTPHRPLILKTGSKFTVRTRLLVRLQEGNESLTVEVSIDRNPPQLQGFRKFNILTSNQKTLTPEKGQSQGLIWDFGYLTLVEQRSGGSGKGSNKGPLGVTEELHIISFTVKYTYQGLKQELKTDTLPVVIISNMNQLSIAWASVLWFNLLSPNLQNQQFFSNPPKAPWSLLGPALSWQFSSYVGRGLNSDQLSMLRNKLFGQNCRTEDPLLSWADFTKRESPPGKLPFWTWLDKILELVHDHLKDLWNDGRIMGFVSRSQERRLLKKTMSGTFLLRFSESSEGGITCSWVEHQDDDKVLIYSVQPYTKEVLQSLPLTEIIRHYQLLTEENIPENPLRFLYPRIPRDEAFGCYYQEKVNLQERRKYLKHRLIVVSNRQVDELQQPLELK

来源 Source

来源生物 organism	Homo sapiens
通用名 common_name	human
NCBI Class编号 ncbi_taxonomy_id	9606
宿主生物 host_organism	Spodoptera frugiperda

Entity 3 Entity 3 polymer

Description description	Ubiquitin-like protein ISG15
Molecular weight formula_weight	17147.6 kDa
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	I

MGWDLTVKMLAGNEFQVSLSSSMSVSELKAQITQKIGVHAFQQRLAVHPSGVALQDRVPLASQGLGPGSTVLLVVDKSDEPLSILVRNNKGRSSTYEVRLTQTVAHLKQQVSGLEGVQDDLFWLTFEGKPLEDQLPLGEYGLKPLSTVFMNLRLRGG

来源 Source

来源生物 organism	Homo sapiens
通用名 common_name	human
NCBI Class编号 ncbi_taxonomy_id	9606
宿主生物 host_organism	Spodoptera frugiperda

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8. Citations (1)

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Unit-cell length a length_a	1.000 Å
Unit-cell length b length_b	1.000 Å
Unit-cell length c length_c	1.000 Å
Unit-cell angle α angle_alpha	90.00 °
Unit-cell angle β angle_beta	90.00 °
Unit-cell angle γ angle_gamma	90.00 °
Molecules per unit cell Z z_pdb	—

Space group space_group	P 1
Space-group number int_tables_number	1
Crystal system crystal_system	—

Resolution resolution	3.050 Å
Low-resolution limit resolution_low	— Å
R factor r_factor	—
R_work r_work	—
R_free r_free	—

Resolution resolution	3.05 Å
Resolution测定方法 resolution_method	—
颗粒数 num_particles	143496

fit	/app/data/saxs_computation/zf/9zfo/9zfo.fit
pddf	/app/data/pr_computation/zf/9zfo/9zfo.pr.out
profile	/app/data/saxs_computation/zf/9zfo/9zfo.dat

Cryo-EM Structure of Human STAT2-USP18-ISG15 Complex

1. Protein Identity and Related Structures Protein Identity & Related Structures

Ubl carboxyl-terminal hydrolase 18

State in the Current Structure

Other States of the Same Protein in the Database

Signal transducer and activator of transcription 2

State in the Current Structure

Other States of the Same Protein in the Database

Ubiquitin-like protein ISG15

State in the Current Structure

Other States of the Same Protein in the Database

SAXS scattering curve SAXS Profile

P(r) Distance Distribution P(r) Distribution

2. Structure Basics 2. Structure Basics

3. SAXS Parameters (CRYSOL theoretical calculation) 3. SAXS Parameters (CRYSOL)

4. P(r) Distance Distribution (GNOM inversion) 4. P(r) Analysis (GNOM)

5. Crystallography and Experiment 5. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

Refinement Refinement

冷冻电镜 EM 3D

6. Entities and Polymers Entities & Polymers (3)

Entity 1 Entity 1 polymer

Polymer Polymer

来源 Source

Entity 2 Entity 2 polymer

Polymer Polymer

来源 Source

Entity 3 Entity 3 polymer

Polymer Polymer

来源 Source

8. Citations (1)

9. Files and Curves (10)

Files (7)

Curves (3)