9r2e

Structure of ARGX-121 Fab fragment in complex with the Fc fragment of IgA1

Method: X-RAY DIFFRACTION

▼

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

Isoform 1 of Immunoglobulin heavy constant alpha 1

Homo sapiens

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 6	ARGX-121 Fab fragment heavy chain × 2 ARGX-121 Fab fragment light chain × 2 1,2-ETHANEDIOL × 4 DI(HYDROXYETHYL)ETHER × 5 MAGNESIUM ION × 3 water × 6	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	IGHA1_HUMAN
Isoform	P01876-1
PDB entities	3
Chains and sequence ranges	Author chain P； PDBConstruct 1–213； UniProt 123–335 Author chain Q； PDBConstruct 1–213； UniProt 123–335

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.

▼

2. Structure Basics 2. Structure Basics

Entry ID entry_id	9r2e
Deposition date deposition_date	2025-04-30
Last revision last_revision	2025-05-14
Structure title title	Structure of ARGX-121 Fab fragment in complex with the Fc fragment of IgA1
Keywords keywords	Antibody, immune system, IgA mediated autoimmunity, immunoglobulin, PROTEROS BIOSTRUCTURES GMBH; IMMUNE SYSTEM
Experimental Method method	X-RAY DIFFRACTION

▼

3. Official assembly/model SAXS Official SAXS Profiles

This page reads only the latest assembly calculations. Every curve maps to an explicit PDB entry, official biological assembly and coordinate model.

9r2e__assembly_1__model_1

Assembly 1 · Model 1 · CRYSOL 4.1.3-1-20251215 (887e7ef)

Download this curve (.dat)

9r2e__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

9r2e__assembly_1__model_1 | P(r) · Pending

P(r) will be calculated and displayed separately for the same assembly/model.

Rg（Guinier）	48.93 Å
Rg (electron density)	50.11 Å
Total Rg	50.11 Å
Atom count	9665
Residues	1283
Excluded volume	171460 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`9r2e__assembly_1__model_1`	hexameric （6）	Success	4.1.3-1-20251215 (887e7ef)	View Download

▶

4. Crystallography and Experiment 4. Crystallography & Experiment

▶

5. Entities and Polymers Entities & Polymers (7)

Entity 1 Entity 1 polymer

Description description	ARGX-121 Fab fragment heavy chain
Molecular weight formula_weight	25904.1 kDa
Source method src_method	man
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	H,A
Atom count atom_count	10097

MGWSCIILFLVATATGVHSEVQLLESGGGLVQPGGSLRLSCAASGFTSSNYLMSWVRQAPGKGLEWVSSIYHYGHNAYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAKVDSAYDFGSWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTH

Source Source

Source organism organism	Homo sapiens
NCBI taxonomy ID ncbi_taxonomy_id	9606
Host organism host_organism	Cricetulus griseus

Entity 2 Entity 2 polymer

Description description	ARGX-121 Fab fragment light chain
Molecular weight formula_weight	24725.7 kDa
Source method src_method	man
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	L,B

MGWSCIILFLVATATGVHSQSVLTQPPSVSGAPGQRVTISCAGTSSDIGGRTYVSWYQQLPGTAPKLLIYKVTIRASGVPDRFSGSKSGTSASLAITGLQAEDEADYYCASHRSNNNIVFGGGTKLTVLGQPKAAPSVTLFPPSSEELQANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPSKQSNNKYAASSYLSLTPEQWKSHRSYSCQVTHEGSTVEKTVAPTECS

Source Source

Source organism organism	Homo sapiens
NCBI taxonomy ID ncbi_taxonomy_id	9606
Host organism host_organism	Cricetulus griseus

Entity 3 Entity 3 polymer

Description description	Isoform 1 of Immunoglobulin heavy constant alpha 1
Molecular weight formula_weight	23155.3 kDa
Source method src_method	man
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	P,Q

CHPRLSLHRPALEDLLLGSEANLTCTLTGLRDASGVTFTWTPSSGKSAVQGPPERDLCGCYSVSSVLPGCAEPWNHGKTFTCTAAYPESKTPLTATLSKSGNTFRPEVHLLPPPSEELALNELVTLTCLARGFSPKDVLVRWLQGSQELPREKYLTWASRQEPSQGTTTFAVTSILRVAAEDWKKGDTFSCMVGHEALPLAFTQKTIDRLAGK

Source Source

Source organism organism	Homo sapiens
Common name common_name	human
NCBI taxonomy ID ncbi_taxonomy_id	9606
Host organism host_organism	Homo sapiens

Entity 4 Entity 4 non-polymer

Description description	1,2-ETHANEDIOL
Molecular weight formula_weight	62.1 kDa
Source method src_method	syn
Copy count entity_count	4

Entity 5 Entity 5 non-polymer

Description description	DI(HYDROXYETHYL)ETHER
Molecular weight formula_weight	106.1 kDa
Source method src_method	syn
Copy count entity_count	5

Entity 6 Entity 6 non-polymer

Description description	MAGNESIUM ION
Molecular weight formula_weight	24.3 kDa
Source method src_method	syn
Copy count entity_count	3

Entity 7 Entity 7 water

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	377

▶

Unit-cell length a length_a	77.291 Å
Unit-cell length b length_b	232.312 Å
Unit-cell length c length_c	105.519 Å
Unit-cell angle α angle_alpha	90.00 °
Unit-cell angle β angle_beta	90.35 °
Unit-cell angle γ angle_gamma	90.00 °
Molecules per unit cell Z z_pdb	8

Space group space_group	C 1 2 1
Space-group number int_tables_number	5
Crystal system crystal_system	—

Resolution resolution	2.540 Å
Low-resolution limit resolution_low	116.160 Å
R factor r_factor	0.2131
R_work r_work	0.2109
R_free r_free	0.2518

Structure of ARGX-121 Fab fragment in complex with the Fc fragment of IgA1

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

Isoform 1 of Immunoglobulin heavy constant alpha 1

State in the Current Structure

Other States of the Same Protein in the Database

2. Structure Basics 2. Structure Basics

3. Official assembly/model SAXS Official SAXS Profiles

9r2e__assembly_1__model_1

9r2e__assembly_1__model_1 | I(q)

9r2e__assembly_1__model_1 | P(r) · Pending

4. Crystallography and Experiment 4. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

Refinement Refinement

Diffraction experiment Diffraction

5. Entities and Polymers Entities & Polymers (7)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

Entity 3 Entity 3 polymer

Polymer Polymer

Source Source

Entity 4 Entity 4 non-polymer

Entity 5 Entity 5 non-polymer

Entity 6 Entity 6 non-polymer

Entity 7 Entity 7 water

7. Citations (1)

Structure of ARGX-121 Fab fragment in complex with the Fc fragment of IgA1

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

Isoform 1 of Immunoglobulin heavy constant alpha 1

State in the Current Structure

Other States of the Same Protein in the Database

Monomer

Homodimer

Homotetramer

Other homooligomers

Heteromeric or nucleic-acid complex

2. Structure Basics 2. Structure Basics

3. Official assembly/model SAXS Official SAXS Profiles

9r2e__assembly_1__model_1

9r2e__assembly_1__model_1 | I(q)

9r2e__assembly_1__model_1 | P(r) · Pending

4. Crystallography and Experiment 4. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

Refinement Refinement

Diffraction experiment Diffraction

5. Entities and Polymers Entities & Polymers (7)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

Entity 3 Entity 3 polymer

Polymer Polymer

Source Source

Entity 4 Entity 4 non-polymer

Entity 5 Entity 5 non-polymer

Entity 6 Entity 6 non-polymer

Entity 7 Entity 7 water

7. Citations (1)