SAXSdb — 2qtj

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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 × 4 PDB declaration: tetrameric（4） Consistent with protein copy count	Chain A； UniProt 1–475 Chain B； UniProt 1–475	Not recorded	Kappa light chain IgA1 × 2	SOLUTION SCATTERING mmCIF provides none of the parsed experimental conditions	Resolution not provided
2	Protein heterocomplex Heteromer Protein × 4 PDB declaration: tetrameric（4） Consistent with protein copy count	Chain C； UniProt 1–475 Chain D； UniProt 1–475	Not recorded	Kappa light chain IgA1 × 2	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 2QTJ	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	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 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 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 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
3CHN Solution structure of human secretory IgA1 Deposited 2008-03-10	Different construct Different mutation/modification Different oligomeric state	Assembly 1 Protein heterocomplex Heteromer；Protein × 10 PDB declaration: decameric	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	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 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 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 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 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 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 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 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 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 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 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 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 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 mutation/modification 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 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 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 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 16 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 1–475； UniProt 1–475 Author chain B； PDBConstruct 1–475； UniProt 1–475 Author chain C； PDBConstruct 1–475； UniProt 1–475 Author chain D； PDBConstruct 1–475； UniProt 1–475

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	2qtj
Deposition date deposition_date	2007-08-02
Structure title title	Solution structure of human dimeric immunoglobulin A
Keywords keywords	;X-ray and neutron solution scattering, immunology, antibody, immunoglobulin A1, Chromophore, Glycoprotein, Immunoglobulin C region, Immunoglobulin domain, 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	97.68 Å
Radius of gyration Rg (electron density) rg_electron	98.56 Å
Forward intensity I(0) i0	124231000000.00
Molecular weight molecular_weight	2968600.0 kDa
Excluded volume excluded_volume	3600600 Å³
Envelope volume envelope_volume	1727900 Å³
Hydration-shell volume shell_volume	135930 Å³
Envelope diameter envelope_diameter	303.7 Å
Shell Rg shell_rg	91.68 Å
Envelope Rg envelope_rg	99.99 Å
Shape Rg shape_rg	98.65 Å
Total Rg total_rg	98.55 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	253.9 Å
Rg (real space) rg_real	94.20 Å
Rg uncertainty (real space) rg_real_error	1.23 Å
I(0) (real space) i0_real	1.2030e+11
I(0) uncertainty (real space) i0_real_error	2.6820e+09
Rg (reciprocal space) rg_reciprocal	92.00 Å
I(0) (reciprocal space) i0_reciprocal	121900000000.0000
Solution quality estimate total_estimate	0.8939
Solution quality rating solution_quality	GOOD a GOOD solution
P(r) peaks n_peaks	2
Primary peak position r_peak_primary	95.2 Å
Skewness Skewness skewness	0.288
Kurtosis Kurtosis kurtosis	-0.809
Angular range angular_range	— – 0.0800 Å⁻¹
Current regularization parameter α current_alpha	0.1864
Highest regularization parameter α highest_alpha	62780000.0000
Real-space data points n_real_points	17
GNOM version gnom_version	4.1.3
Quality Criteria quality_criteria	AN1: 0.000; Oscil: 0.810; Stabil: 0.922; Sysdev: 1.000; Positv: 1.000; Valcen: 0.879; Smooth: 0.555

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5. Crystallography and Experiment 5. Crystallography & Experiment

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6. Entities and Polymers Entities & Polymers (2)

Entity 1 Entity 1 polymer

Description description	Kappa light chain IgA1
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	27560

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,C,D

QVKLLEQSGAEVKKPGASVKVSCKASGYSFTSYGLHWVRQAPGQRLEWMGWISAGTGNTKYSQKFRGRVTFTRDTSATTAYMGLSSLRPEDTAVYYCARDPYGGGKSEFDYWGQGTLVTVSSASPTSPKVFPLSLCSTQPDGNVVIACLVQGFFPQEPLSVTWSESGQGVTARNFPPSQDASGDLYTTSSQLTLPATQCLAGKSVTCHVKHYTNPSQDVTVPCPVPSTPPTPSPSTPPTPSPSCCHPRLSLHRPALEDLLLGSEANLTCTLTGLRDASGVTFTWTPSSGKSAVQGPPERDLCGCYSVSSVLPGCAEPWNHGKTFTCTAAYPESKTPLTATLSKSGNTFRPEVHLLPPPSEELALNELVTLTCLARGFSPKDVLVRWLQGSQELPREKYLTWASRQEPSQGTTTFAVTSILRVAAEDWKKGDTFSCMVGHEALPLAFTQKTIDRLAGKPTHVNVSVVMAEVDGTCY

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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	1

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

fit	/app/data/saxs_computation/qt/2qtj/2qtj.fit
pddf	/app/data/pr_computation/qt/2qtj/2qtj.pr.out
profile	/app/data/saxs_computation/qt/2qtj/2qtj.dat

Solution structure of human dimeric immunoglobulin A

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

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 (2)

Entity 1 Entity 1 polymer

Polymer Polymer

Entity 2 Entity 2 polymer

Polymer Polymer

8. Citations (1)

9. Files and Curves (10)

Files (7)

Curves (3)