SAXSdb — 3chn

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

Ig alpha-1 chain C region

OrganismNot specified

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 × 10 PDB declaration: decameric（10） Consistent with protein copy count	Chain A； UniProt 1–353 Chain B； UniProt 1–353 Chain C； UniProt 1–353 Chain D； UniProt 1–353	Not recorded	Immunoglobulin kappa light chain × 4 Secretory component × 1 （P01833） Secretory component × 1 （P01833）	SOLUTION SCATTERING mmCIF provides none of the parsed experimental conditions	Resolution not provided

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 3CHN	Assembly / Oligomeric State	Construct	Mutations and Modifications	Ligands, Ions and Non-polymers	Method and Experimental Conditions	Structure Quality
1IGA MODEL OF HUMAN IGA1 DETERMINED BY SOLUTION SCATTERING CURVE-FITTING AND HOMOLOGY MODELLING Deposited 1998-12-23	Different construct Different mutation/modification Different oligomeric state	Assembly 1 Protein heterocomplex Heteromer；Protein × 4 PDB declaration: tetrameric	Chain A 1–353（353 aa） Fragment：CHAINS A AND B, HEAVY, CHAINS C AND D, LIGHT Chain B 1–353（353 aa） Fragment：CHAINS A AND B, HEAVY, CHAINS C AND D, LIGHT	Not recorded	No recorded non-water small molecule	SOLUTION SCATTERING mmCIF provides none of the parsed conditions	Resolution not provided
1OW0 Crystal structure of human FcaRI bound to IgA1-Fc Deposited 2003-03-27	Different construct Different mutation/modification Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Other combination Homooligomer；Protein × 2 PDB declaration: dimeric	Chain A 122–335（214 aa） Fragment：Fc region Chain B 122–335（214 aa） Fragment：Fc region	Not recorded	No recorded non-water small molecule	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 6.5；296 K；magnesium sulfate heptahydrate, MES, pH 6.5, VAPOR DIFFUSION, HANGING DROP, temperature 296K	Resolution 3.10 Å R-free 0.284
1OW0 Crystal structure of human FcaRI bound to IgA1-Fc Deposited 2003-03-27	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 4 Other combination Heteromer；Protein × 4 PDB declaration: tetrameric	Chain A 122–335（214 aa） Fragment：Fc region Chain B 122–335（214 aa） Fragment：Fc region	Not recorded	NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 2	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 6.5；296 K；magnesium sulfate heptahydrate, MES, pH 6.5, VAPOR DIFFUSION, HANGING DROP, temperature 296K	Resolution 3.10 Å R-free 0.284
2QEJ Crystal structure of a Staphylococcus aureus protein (SSL7) in complex with Fc of human IgA1 Deposited 2007-06-26	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Other combination Heteromer；Protein × 4 PDB declaration: pentameric	Chain A 123–336（214 aa） Fragment：FC REGION Chain B 123–336（214 aa） Fragment：FC REGION	Not recorded	GOL GLYCEROL × 5 CA CALCIUM ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION；pH 6.5；291 K；12% PEG 8000, 66 mM sodium cacodylate pH 6.5, 130 mM calcium acetate, VAPOR DIFFUSION, temperature 291K	Resolution 3.20 Å R-free 0.312
2QTJ Solution structure of human dimeric immunoglobulin A Deposited 2007-08-02	Different construct Different mutation/modification Different oligomeric state	Assembly 1 Protein heterocomplex Heteromer；Protein × 4 PDB declaration: tetrameric	Chain A 1–475（475 aa） Chain B 1–475（475 aa）	Not recorded	No recorded non-water small molecule	SOLUTION SCATTERING mmCIF provides none of the parsed conditions	Resolution not provided
2QTJ Solution structure of human dimeric immunoglobulin A Deposited 2007-08-02	Different construct Different mutation/modification Different oligomeric state	Assembly 2 Protein heterocomplex Heteromer；Protein × 4 PDB declaration: tetrameric	Chain C 1–475（475 aa） Chain D 1–475（475 aa）	Not recorded	No recorded non-water small molecule	SOLUTION SCATTERING mmCIF provides none of the parsed conditions	Resolution not provided
6LX3 Cryo-EM structure of human secretory immunoglobulin A Deposited 2020-02-10	Different construct Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Insufficient information Heteromer；Protein × 6 PDB declaration: hexameric	Chain A 122–353（232 aa） Chain B 122–353（232 aa） Chain C 122–353（232 aa） Chain D 122–353（232 aa）	Not recorded	No recorded non-water small molecule	ELECTRON MICROSCOPY cryo-EM buffer pH 7.4 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.15 Å
6LXW Cryo-EM structure of human secretory immunoglobulin A in complex with the N-terminal domain of SpsA Deposited 2020-02-12	Different construct Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Insufficient information Heteromer；Protein × 7 PDB declaration: heptameric	Chain A 122–353（232 aa） Chain B 122–353（232 aa） Chain C 122–353（232 aa） Chain D 122–353（232 aa）	Not recorded	No recorded non-water small molecule	ELECTRON MICROSCOPY cryo-EM buffer pH 7.4 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.27 Å
6UE7 Structure of dimeric sIgA complex Deposited 2019-09-20	Different construct Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Other combination Heteromer；Protein × 6 PDB declaration: hexameric	Chain A 123–353（231 aa） Fragment：UNP residues 123-353 Chain B 123–353（231 aa） Fragment：UNP residues 123-353 Chain F 123–353（231 aa） Fragment：UNP residues 123-353 Chain G 123–353（231 aa） Fragment：UNP residues 123-353	Not recorded	NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 7	ELECTRON MICROSCOPY cryo-EM buffer pH 7.2 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 2.90 Å
6XJA Streptococcus Pneumoniae IgA1 Protease with IgA1 substrate Deposited 2020-06-23	Different construct Different mutation/modification Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 5 PDB declaration: pentameric	Chain A 122–331（210 aa） Chain B 122–331（210 aa）	Not recorded	No recorded non-water small molecule	ELECTRON MICROSCOPY cryo-EM buffer pH 7；20 mM Hepes, pH 7 150 mM NaCl cryo-EM vitrification conditions Cryogen ETHANE	Resolution 4.00 Å
7UVL IgA1 Protease with IgA1 substrate Deposited 2022-05-02	Different construct Different mutation/modification Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein heterocomplex Heteromer；Protein × 5 PDB declaration: pentameric	Chain A 123–331（209 aa） Chain B 123–331（209 aa）	Not recorded	No recorded non-water small molecule	ELECTRON MICROSCOPY cryo-EM buffer pH 7.4 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.56 Å
8SKU Structure of human SIgA1 in complex with human CD89 (FcaR1) Deposited 2023-04-20	Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Other combination Heteromer；Protein × 8 PDB declaration: octameric	Chain A 1–353（353 aa） Chain B 1–353（353 aa） Chain C 1–353（353 aa） Chain D 1–353（353 aa）	Not recorded	NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 4	ELECTRON MICROSCOPY cryo-EM buffer pH 7 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.20 Å
8SKV Structure of human SIgA1 in complex with Streptococcus pyogenes protein M4 (Arp4) Deposited 2023-04-20	Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Other combination Heteromer；Protein × 8 PDB declaration: octameric	Chain A 1–353（353 aa） Chain B 1–353（353 aa） Chain C 1–353（353 aa） Chain D 1–353（353 aa）	Not recorded	NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 7	ELECTRON MICROSCOPY cryo-EM buffer pH 7 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.10 Å
9MBZ Cryo-EM structure of human FcRL4 bound to IgA-Fc/J Deposited 2025-03-17	Different construct Different oligomeric state Different experimental method Different structure-quality metrics	Assembly 1 Insufficient information Heteromer；Protein × 6 PDB declaration: hexameric	Chain A 122–353（232 aa） Chain B 122–353（232 aa） Chain C 122–353（232 aa） Chain D 122–353（232 aa）	Not recorded	No recorded non-water small molecule	ELECTRON MICROSCOPY mmCIF provides none of the parsed conditions	Resolution 3.30 Å
9OFR CRYSTAL STRUCTURE OF THE HUMAN IGA1 FC FRAGMENT-FC-ALPHA RECEPTOR (CD89) COMPLEX Deposited 2025-04-30	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Other combination Heteromer；Protein × 4 PDB declaration: tetrameric	Chain A 123–335（213 aa） Fragment：FC fragment, UNP residues 123-335 Chain B 123–335（213 aa） Fragment：FC fragment, UNP residues 123-335	Not recorded	NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 7	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 8；294 K；0.15M sodium chloride 0.1M Tris-HCl pH 8.0 8% PEG 6000	Resolution 2.65 Å R-free 0.264
9OFR CRYSTAL STRUCTURE OF THE HUMAN IGA1 FC FRAGMENT-FC-ALPHA RECEPTOR (CD89) COMPLEX Deposited 2025-04-30	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 × 4 PDB declaration: tetrameric	Chain E 123–335（213 aa） Fragment：FC fragment, UNP residues 123-335 Chain G 123–335（213 aa） Fragment：FC fragment, UNP residues 123-335	Not recorded	NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 7	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, HANGING DROP；pH 8；294 K；0.15M sodium chloride 0.1M Tris-HCl pH 8.0 8% PEG 6000	Resolution 2.65 Å R-free 0.264
9R2E Structure of ARGX-121 Fab fragment in complex with the Fc fragment of IgA1 Deposited 2025-04-30	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 × 6 PDB declaration: hexameric	Chain P 123–335（213 aa） Chain Q 123–335（213 aa）	Not recorded	EDO 1,2-ETHANEDIOL × 4 PEG DI(HYDROXYETHYL)ETHER × 5 MG MAGNESIUM ION × 3	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；277 K；16% (w/v) PEG8000, 20% (v/v) Glycerol, 0.16 M MgAcetate, 0.08 M Na Cacodylate pH 6.50	Resolution 2.54 Å R-free 0.252

14 other PDB entries and 17 assemblies. Open the comparison page and filter oligomeric states

View Construct and Data Evidence

UniProt name	IGHA1_HUMAN
Isoform	—
PDB entities	2
Chains and sequence ranges	Author chain A； PDBConstruct 123–475； UniProt 1–353 Author chain B； PDBConstruct 123–475； UniProt 1–353 Author chain C； PDBConstruct 123–475； UniProt 1–353 Author chain D； PDBConstruct 123–475； UniProt 1–353

Secretory component

OrganismNot specified

UniProt P01833

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 × 10 PDB declaration: decameric（10） Consistent with protein copy count	Chain J； UniProt 353–458 Chain S； UniProt 19–603	Fragment：Ig-like V-type domain 4	Immunoglobulin kappa light chain × 4 Ig alpha-1 chain C region × 4 （P01876）	SOLUTION SCATTERING mmCIF provides none of the parsed experimental conditions	Resolution not provided

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 3CHN	Assembly / Oligomeric State	Construct	Mutations and Modifications	Ligands, Ions and Non-polymers	Method and Experimental Conditions	Structure Quality
1XED Crystal Structure of a Ligand-Binding Domain of the Human Polymeric Ig Receptor, pIgR Deposited 2004-09-10	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric	Chain A 19–127（109 aa） Fragment：N-Terminal Domain I	Not recorded	MG MAGNESIUM ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions pH 6.5；293 K；PEG 8000, Magnesium acetate, cacodylate, pH 6.5, VAPOR DIFFUSION, HANGING DROP, temperature 293K, pH 6.50	Resolution 1.90 Å R-free 0.244
1XED Crystal Structure of a Ligand-Binding Domain of the Human Polymeric Ig Receptor, pIgR Deposited 2004-09-10	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 2 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric	Chain B 19–127（109 aa） Fragment：N-Terminal Domain I	Not recorded	MG MAGNESIUM ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions pH 6.5；293 K；PEG 8000, Magnesium acetate, cacodylate, pH 6.5, VAPOR DIFFUSION, HANGING DROP, temperature 293K, pH 6.50	Resolution 1.90 Å R-free 0.244
1XED Crystal Structure of a Ligand-Binding Domain of the Human Polymeric Ig Receptor, pIgR Deposited 2004-09-10	Different construct Different mutation/modification 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 19–127（109 aa） Fragment：N-Terminal Domain I	Not recorded	No recorded non-water small molecule	X-RAY DIFFRACTION X-ray crystallization conditions pH 6.5；293 K；PEG 8000, Magnesium acetate, cacodylate, pH 6.5, VAPOR DIFFUSION, HANGING DROP, temperature 293K, pH 6.50	Resolution 1.90 Å R-free 0.244
1XED Crystal Structure of a Ligand-Binding Domain of the Human Polymeric Ig Receptor, pIgR Deposited 2004-09-10	Different construct Different mutation/modification 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 19–127（109 aa） Fragment：N-Terminal Domain I	Not recorded	No recorded non-water small molecule	X-RAY DIFFRACTION X-ray crystallization conditions pH 6.5；293 K；PEG 8000, Magnesium acetate, cacodylate, pH 6.5, VAPOR DIFFUSION, HANGING DROP, temperature 293K, pH 6.50	Resolution 1.90 Å R-free 0.244
1XED Crystal Structure of a Ligand-Binding Domain of the Human Polymeric Ig Receptor, pIgR Deposited 2004-09-10	Different construct Different mutation/modification 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 19–127（109 aa） Fragment：N-Terminal Domain I	Not recorded	No recorded non-water small molecule	X-RAY DIFFRACTION X-ray crystallization conditions pH 6.5；293 K；PEG 8000, Magnesium acetate, cacodylate, pH 6.5, VAPOR DIFFUSION, HANGING DROP, temperature 293K, pH 6.50	Resolution 1.90 Å R-free 0.244
1XED Crystal Structure of a Ligand-Binding Domain of the Human Polymeric Ig Receptor, pIgR Deposited 2004-09-10	Different construct Different mutation/modification 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 19–127（109 aa） Fragment：N-Terminal Domain I	Not recorded	No recorded non-water small molecule	X-RAY DIFFRACTION X-ray crystallization conditions pH 6.5；293 K；PEG 8000, Magnesium acetate, cacodylate, pH 6.5, VAPOR DIFFUSION, HANGING DROP, temperature 293K, pH 6.50	Resolution 1.90 Å R-free 0.244
1XED Crystal Structure of a Ligand-Binding Domain of the Human Polymeric Ig Receptor, pIgR Deposited 2004-09-10	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 7 Protein homooligomer Homooligomer；Protein × 4 PDB declaration: tetrameric	Chain A 19–127（109 aa） Fragment：N-Terminal Domain I Chain B 19–127（109 aa） Fragment：N-Terminal Domain I Chain C 19–127（109 aa） Fragment：N-Terminal Domain I Chain D 19–127（109 aa） Fragment：N-Terminal Domain I	Not recorded	MG MAGNESIUM ION × 2	X-RAY DIFFRACTION X-ray crystallization conditions pH 6.5；293 K；PEG 8000, Magnesium acetate, cacodylate, pH 6.5, VAPOR DIFFUSION, HANGING DROP, temperature 293K, pH 6.50	Resolution 1.90 Å R-free 0.244
1XED Crystal Structure of a Ligand-Binding Domain of the Human Polymeric Ig Receptor, pIgR Deposited 2004-09-10	Different construct Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 8 Protein homooligomer Homooligomer；Protein × 2 PDB declaration: dimeric	Chain B 19–127（109 aa） Fragment：N-Terminal Domain I Chain D 19–127（109 aa） Fragment：N-Terminal Domain I	Not recorded	MG MAGNESIUM ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions pH 6.5；293 K；PEG 8000, Magnesium acetate, cacodylate, pH 6.5, VAPOR DIFFUSION, HANGING DROP, temperature 293K, pH 6.50	Resolution 1.90 Å R-free 0.244
1XED Crystal Structure of a Ligand-Binding Domain of the Human Polymeric Ig Receptor, pIgR Deposited 2004-09-10	Different construct Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 9 Protein homooligomer Homooligomer；Protein × 2 PDB declaration: dimeric	Chain A 19–127（109 aa） Fragment：N-Terminal Domain I Chain C 19–127（109 aa） Fragment：N-Terminal Domain I	Not recorded	MG MAGNESIUM ION × 1	X-RAY DIFFRACTION X-ray crystallization conditions pH 6.5；293 K；PEG 8000, Magnesium acetate, cacodylate, pH 6.5, VAPOR DIFFUSION, HANGING DROP, temperature 293K, pH 6.50	Resolution 1.90 Å R-free 0.244
2OCW Solution structure of human secretory component Deposited 2006-12-21	Different construct Different mutation/modification Different oligomeric state	Assembly 1 Protein monomer Monomer；Protein × 1 PDB declaration: monomeric	Chain A 19–603（585 aa）	Not recorded	No recorded non-water small molecule	SOLUTION SCATTERING mmCIF provides none of the parsed conditions	Resolution not provided
3CM9 Solution Structure of Human SIgA2 Deposited 2008-03-21	Parsed fields agree	Assembly 1 Protein heterocomplex Heteromer；Protein × 10 PDB declaration: decameric	Chain J 353–458（106 aa） Fragment：Ig-like V-type domain 4 Chain S 19–603（585 aa）	Not recorded	No recorded non-water small molecule	SOLUTION SCATTERING mmCIF provides none of the parsed conditions	Resolution not provided
5D4K Crystal structure of the human polymeric Ig receptor (pIgR) ectodomain Deposited 2015-08-07	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Other combination Monomer；Protein × 1 PDB declaration: monomeric	Chain A 19–565（547 aa） Fragment：ectodomain (UNP residues 19-565)	Not recorded	NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 3 SO4 SULFATE ION × 2	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 5.5；295 K；0.2 M ammonium sulfate, 0.1M BisTris pH 5.5, 31% Polyethylene glycol 3350	Resolution 2.60 Å R-free 0.254
5D4K Crystal structure of the human polymeric Ig receptor (pIgR) ectodomain Deposited 2015-08-07	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 2 Other combination Monomer；Protein × 1 PDB declaration: monomeric	Chain B 19–565（547 aa） Fragment：ectodomain (UNP residues 19-565)	Not recorded	NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 3 SO4 SULFATE ION × 2	X-RAY DIFFRACTION X-ray crystallization conditions VAPOR DIFFUSION, SITTING DROP；pH 5.5；295 K；0.2 M ammonium sulfate, 0.1M BisTris pH 5.5, 31% Polyethylene glycol 3350	Resolution 2.60 Å R-free 0.254
6KXS Cryo-EM structure of human IgM-Fc in complex with the J chain and the ectodomain of pIgR Deposited 2019-09-12	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Other combination Heteromer；Protein × 12 PDB declaration: dodecameric	Chain P 19–565（547 aa）	Not recorded	NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 10	ELECTRON MICROSCOPY cryo-EM buffer pH 7.4 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.40 Å
6LX3 Cryo-EM structure of human secretory immunoglobulin A Deposited 2020-02-10	Different construct Different mutation/modification Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Insufficient information Heteromer；Protein × 6 PDB declaration: hexameric	Chain P 1–565（565 aa）	Not recorded	No recorded non-water small molecule	ELECTRON MICROSCOPY cryo-EM buffer pH 7.4 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.15 Å
6LXW Cryo-EM structure of human secretory immunoglobulin A in complex with the N-terminal domain of SpsA Deposited 2020-02-12	Different construct Different mutation/modification Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Insufficient information Heteromer；Protein × 7 PDB declaration: heptameric	Chain P 1–565（565 aa）	Not recorded	No recorded non-water small molecule	ELECTRON MICROSCOPY cryo-EM buffer pH 7.4 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.27 Å
6UE7 Structure of dimeric sIgA complex Deposited 2019-09-20	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Other combination Heteromer；Protein × 6 PDB declaration: hexameric	Chain C 19–603（585 aa） Fragment：UNP residues 19-603	Not recorded	NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 7	ELECTRON MICROSCOPY cryo-EM buffer pH 7.2 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 2.90 Å
6UE8 Structure of tetrameric sIgA complex (Class 1) Deposited 2019-09-20	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Other combination Heteromer；Protein × 10 PDB declaration: decameric	Chain C 19–603（585 aa） Fragment：UNP residues 19-603	Not recorded	NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 5	ELECTRON MICROSCOPY cryo-EM buffer pH 7.2 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.00 Å
6UE9 Structure of tetrameric sIgA complex (Class 2) Deposited 2019-09-20	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Other combination Heteromer；Protein × 10 PDB declaration: decameric	Chain C 19–603（585 aa） Fragment：UNP residues 19-603	Not recorded	NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 7	ELECTRON MICROSCOPY cryo-EM buffer pH 7.2 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 2.90 Å
6UEA Structure of pentameric sIgA complex Deposited 2019-09-20	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Other combination Heteromer；Protein × 12 PDB declaration: dodecameric	Chain C 19–603（585 aa） Fragment：UNP residues 19-603	Not recorded	NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 2	ELECTRON MICROSCOPY cryo-EM buffer pH 7.2 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.00 Å
7K0C Structure of Secretory IgM Core Deposited 2020-09-04	Different construct Different mutation/modification Different oligomeric state Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Other combination Heteromer；Protein × 12 PDB declaration: dodecameric	Chain C 19–603（585 aa）	Not recorded	No recorded non-water small molecule	ELECTRON MICROSCOPY cryo-EM buffer pH 7.2 cryo-EM vitrification conditions Cryogen ETHANE；Blot for 3.5 seconds before plunging with blot force 7.	Resolution 3.30 Å
7YSG Cryo-EM structure of human FcmR bound to sIgM Deposited 2022-08-12	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Other combination Heteromer；Protein × 16 PDB declaration: hexadecameric	Chain P 19–559（541 aa）	Not recorded	NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 10	ELECTRON MICROSCOPY cryo-EM buffer pH 7.4 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.18 Å
8SKU Structure of human SIgA1 in complex with human CD89 (FcaR1) Deposited 2023-04-20	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Other combination Heteromer；Protein × 8 PDB declaration: octameric	Chain E 19–565（547 aa）	Not recorded	NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 4	ELECTRON MICROSCOPY cryo-EM buffer pH 7 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.20 Å
8SKV Structure of human SIgA1 in complex with Streptococcus pyogenes protein M4 (Arp4) Deposited 2023-04-20	Different construct Different mutation/modification Different oligomeric state Different ligand/ion Different experimental method Different experimental conditions Different structure-quality metrics	Assembly 1 Other combination Heteromer；Protein × 8 PDB declaration: octameric	Chain E 19–565（547 aa）	Not recorded	NAG 2-acetamido-2-deoxy-beta-D-glucopyranose × 7	ELECTRON MICROSCOPY cryo-EM buffer pH 7 cryo-EM vitrification conditions Cryogen ETHANE	Resolution 3.10 Å

15 other PDB entries and 24 assemblies. Open the comparison page and filter oligomeric states

View Construct and Data Evidence

UniProt name	PIGR_HUMAN
Isoform	—
PDB entities	3, 4
Chains and sequence ranges	Author chain J； PDBConstruct 1–106； UniProt 353–458 Author chain S； PDBConstruct 1–585； UniProt 19–603

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.

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2. Structure Basics 2. Structure Basics

Entry ID entry_id	3chn
Deposition date deposition_date	2008-03-10
Structure title title	Solution structure of human secretory IgA1
Keywords keywords	;Immunoglobulin A, Secretory immunoglobulin A, Mucosal immunity, neutron scattering, X-ray scattering, Chromophore, Glycoprotein, Immunoglobulin C region, Immunoglobulin domain, Membrane, Phosphoprotein, Secreted, Transmembrane, IMMUNE SYSTEM ;; IMMUNE SYSTEM
Experimental Method method	SOLUTION SCATTERING

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

Radius of gyration Rg (Guinier) rg_guinier	89.50 Å
Radius of gyration Rg (electron density) rg_electron	89.86 Å
Forward intensity I(0) i0	195871000000.00
Molecular weight molecular_weight	3729900.0 kDa
Excluded volume excluded_volume	4526600 Å³
Envelope volume envelope_volume	952620 Å³
Hydration-shell volume shell_volume	101280 Å³
Envelope diameter envelope_diameter	275.8 Å
Shell Rg shell_rg	71.27 Å
Envelope Rg envelope_rg	80.11 Å
Shape Rg shape_rg	90.09 Å
Total Rg total_rg	89.83 Å
Total atoms total_atoms	—
Residues n_residues	—
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	239.7 Å
Rg (real space) rg_real	85.99 Å
Rg uncertainty (real space) rg_real_error	0.92 Å
I(0) (real space) i0_real	1.8850e+11
I(0) uncertainty (real space) i0_real_error	3.7710e+09
Rg (reciprocal space) rg_reciprocal	86.78 Å
I(0) (reciprocal space) i0_reciprocal	194200000000.0000
Solution quality estimate total_estimate	0.9105
Solution quality rating solution_quality	EXCELLENT a EXCELLENT solution
P(r) peaks n_peaks	1
Primary peak position r_peak_primary	112.8 Å
Skewness Skewness skewness	0.171
Kurtosis Kurtosis kurtosis	-0.736
Angular range angular_range	— – 0.0850 Å⁻¹
Current regularization parameter α current_alpha	0.9160
Highest regularization parameter α highest_alpha	49890000.0000
Real-space data points n_real_points	18
GNOM version gnom_version	4.1.3
Quality Criteria quality_criteria	AN1: 0.000; Oscil: 0.999; Stabil: 0.967; Sysdev: 1.000; Positv: 1.000; Valcen: 0.946; Smooth: 0.001

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5. Crystallography and Experiment 5. Crystallography & Experiment

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6. Entities and Polymers Entities & Polymers (4)

Entity 1 Entity 1 polymer

Description description	Immunoglobulin kappa light chain
Molecular weight formula_weight	23216.8 kDa
Source method src_method	nat
Copy count entity_count	4

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	L,M,N,O
Atom count atom_count	34470

ELVMTQSPSSLSASVGDRVNIACRASQGISSALAWYQQKPGKAPRLLIYDASNLESGVPSRFSGSGSGTDFTLTISSLQPEDFAIYYCQQFNSYPLTFGGGTKVEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC

Entity 2 Entity 2 polymer

Description description	Ig alpha-1 chain C region
Molecular weight formula_weight	51068.4 kDa
Source method src_method	nat
Copy count entity_count	4

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,B,D,C

QVKLLEQSGAEVKKPGASVKVSCKASGYSFTSYGLHWVRQAPGQRLEWMGWISAGTGNTKYSQKFRGRVTFTRDTSATTAYMGLSSLRPEDTAVYYCARDPYGGGKSEFDYWGQGTLVTVSSASPTSPKVFPLSLCSTQPDGNVVIACLVQGFFPQEPLSVTWSESGQGVTARNFPPSQDASGDLYTTSSQLTLPATQCLAGKSVTCHVKHYTNPSQDVTVPCPVPSTPPTPSPSTPPTPSPSCCHPRLSLHRPALEDLLLGSEANLTCTLTGLRDASGVTFTWTPSSGKSAVQGPPERDLCGCYSVSSVLPGCAEPWNHGKTFTCTAAYPESKTPLTATLSKSGNTFRPEVHLLPPPSEELALNELVTLTCLARGFSPKDVLVRWLQGSQELPREKYLTWASRQEPSQGTTTFAVTSILRVAAEDWKKGDTFSCMVGHEALPLAFTQKTIDRLAGKPTHVNVSVVMAEVDGTCY

Entity 3 Entity 3 polymer

Description description	Secretory component
Molecular weight formula_weight	11850.5 kDa
Source method src_method	nat
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	J

PRSPTVVKGVAGSSVAVLCPYNRKESKSIKYWCLWEGAQNGRCPLLVDSEGWVKAQYEGRLSLLEEPGNGTFTVILNQLTSRDAGFYWCLTNGDTLWRTTVEIKII

Entity 4 Entity 4 polymer

Description description	Secretory component
Molecular weight formula_weight	64355.2 kDa
Source method src_method	nat
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	S

KSPIFGPEEVNSVEGNSVSITCYYPPTSVNRHTRKYWCRQGARGGCITLISSEGYVSSKYAGRANLTNFPENGTFVVNIAQLSQDDSGRYKCGLGINSRGLSFDVSLEVSQGPGLLNDTKVYTVDLGRTVTINCPFKTENAQKRKSLYKQIGLYPVLVIDSSGYVNPNYTGRIRLDIQGTGQLLFSVVINQLRLSDAGQYLCQAGDDSNSNKKNADLQVLKPEPELVYEDLRGSVTFHCALGPEVANVAKFLCRQSSGENCDVVVNTLGKRAPAFEGRILLNPQDKDGSFSVVITGLRKEDAGRYLCGAHSDGQLQEGSPIQAWQLFVNEESTIPRSPTVVKGVAGSSVAVLCPYNRKESKSIKYWCLWEGAQNGRCPLLVDSEGWVKAQYEGRLSLLEEPGNGTFTVILNQLTSRDAGFYWCLTNGDTLWRTTVEIKIIEGEPNLKVPGNVTAVLGETLKVPCHFPCKFSSYEKYWCKWNNTGCQALPSQDEGPSKAFVNCDENSRLVSLTLNLVTRADEGWYWCGVKQGHFYGETAAVYVAVEERKAAGSRDVSLAKADAAPDEKVLDSGFREIENKAIQDPR

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8. Citations (4)

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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	1

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

fit	/app/data/saxs_computation/ch/3chn/3chn.fit
pddf	/app/data/pr_computation/ch/3chn/3chn.pr.out
profile	/app/data/saxs_computation/ch/3chn/3chn.dat

Solution structure of human secretory IgA1

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

Ig alpha-1 chain C region

State in the Current Structure

Other States of the Same Protein in the Database

Secretory component

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

6. Entities and Polymers Entities & Polymers (4)

Entity 1 Entity 1 polymer

Polymer Polymer

Entity 2 Entity 2 polymer

Polymer Polymer

Entity 3 Entity 3 polymer

Polymer Polymer

Entity 4 Entity 4 polymer

Polymer Polymer

8. Citations (4)

9. Files and Curves (10)

Files (7)

Curves (3)