2r56

Crystal Structure of a Recombinant IgE Fab Fragment in Complex with Bovine Beta-Lactoglobulin Allergen

Method: X-RAY DIFFRACTION

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

Beta-lactoglobulin

Bos taurus

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 6	IgE Fab Fragment, light chain × 2 IgE Fab Fragment, heavy chain × 2 DODECYL-BETA-D-MALTOSIDE × 2	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	LACB_BOVIN
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–162； UniProt 17–178 Author chain B； PDBConstruct 1–162； UniProt 17–178

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	2r56
Deposition date deposition_date	2007-09-03
Structure title title	Crystal Structure of a Recombinant IgE Fab Fragment in Complex with Bovine Beta-Lactoglobulin Allergen
Keywords keywords	;Allergen, IgE, Epitope, Immunocomplex, Lipocalin, Fab, Milk protein, Polymorphism, Retinol-binding, Secreted, Transport, IMMUNE SYSTEM ;; IMMUNE SYSTEM
Experimental Method method	X-RAY DIFFRACTION

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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.

2r56__assembly_1__model_1

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

Download this curve (.dat)

2r56__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

2r56__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	48.54 Å
Rg (electron density)	49.90 Å
Total Rg	49.68 Å
Atom count	9136
Residues	1182
Excluded volume	162560 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`2r56__assembly_1__model_1`	hexameric （6）	Success	4.1.3-1-20251215 (887e7ef)	View Download

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4. Crystallography and Experiment 4. Crystallography & Experiment

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5. Entities and Polymers Entities & Polymers (4)

Entity 1 Entity 1 polymer

Description description	Beta-lactoglobulin
Molecular weight formula_weight	18301.2 kDa
Source method src_method	man
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,B
Atom count atom_count	9136

LIVTQTMKGLDIQKVAGTWYSLAMAASDISLLDAQSAPLRVYVEELKPTPEGDLEILLQKWENGECAQKKIIAEKTKIPAVFKIDALNENKVLVLDTDYKKYLLFCMENSAEPEQSLACQCLVRTPEVDDEALEKFDKALKALPMHIRLSFNPTQLEEQCHI

Source Source

Source organism organism	Bos taurus
Common name common_name	cattle
NCBI taxonomy ID ncbi_taxonomy_id	9913
Host organism host_organism	Escherichia coli

Entity 2 Entity 2 polymer

Description description	IgE Fab Fragment, light chain
Molecular weight formula_weight	23116.7 kDa
Source method src_method	nat
Copy count entity_count	2

Polymer Polymer

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

DIVMTQSPSSLSASVGDRVTITCRASQGISSRLAWYQQKPGKAPKLLIYAASSLQSGVPSRFSGSGSGTEFTLTISSLQPEDFATYYCQQYHSYPWTFGQGTKLEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNR

Entity 3 Entity 3 polymer

Description description	IgE Fab Fragment, heavy chain
Molecular weight formula_weight	23446.3 kDa
Source method src_method	nat
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	H,I

QVSLRESGGGLVQPGRSLRLSCTASGFTFRHHGMTWVRQAPGKGLEWVASLSGSGTKTHFADSVKGRFTISRDNSNNTLYLQMDNVRDEDTAIYYCAKAKRVGATGYFDLWGRGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKAEP

Entity 4 Entity 4 non-polymer

Description description	DODECYL-BETA-D-MALTOSIDE
Molecular weight formula_weight	510.6 kDa
Source method src_method	syn
Copy count entity_count	2

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6. Fold Classification (SCOP + CATH) 18 domains

SCOP 2.08 (8 domains)

Domain ID domain_id	d2r56a_
Class class	b — All beta proteins
Fold Fold fold	b.60 — Lipocalins
Superfamily Superfamily superfamily	b.60.1 — Lipocalins
Family Family family	b.60.1.1 — Retinol binding protein-like

Domain ID domain_id	d2r56b_
Class class	b — All beta proteins
Fold Fold fold	b.60 — Lipocalins
Superfamily Superfamily superfamily	b.60.1 — Lipocalins
Family Family family	b.60.1.1 — Retinol binding protein-like

Domain ID domain_id	d2r56h_
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.1 — Immunoglobulin
Family Family family	b.1.1.1 — V set domains (antibody variable domain-like)

Domain ID domain_id	d2r56i_
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.1 — Immunoglobulin
Family Family family	b.1.1.1 — V set domains (antibody variable domain-like)

Domain ID domain_id	d2r56l1
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.1 — Immunoglobulin
Family Family family	b.1.1.0 — automated matches

Domain ID domain_id	d2r56l2
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.1 — Immunoglobulin
Family Family family	b.1.1.2 — C1 set domains (antibody constant domain-like)

Domain ID domain_id	d2r56m1
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.1 — Immunoglobulin
Family Family family	b.1.1.0 — automated matches

Domain ID domain_id	d2r56m2
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.1 — Immunoglobulin
Family Family family	b.1.1.2 — C1 set domains (antibody constant domain-like)

CATH v4.4 (10 domains)

Domain ID domain_id	2r56A00
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	128 — Lipocalin
Homologous superfamily homologous superfamily	20 — Calycin beta-barrel core domain

Domain ID domain_id	2r56B00
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	128 — Lipocalin
Homologous superfamily homologous superfamily	20 — Calycin beta-barrel core domain

Domain ID domain_id	2r56H01
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	2r56H02
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	2r56I01
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	2r56I02
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	2r56L01
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	2r56L02
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	2r56M01
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	2r56M02
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

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Unit-cell length a length_a	67.040 Å
Unit-cell length b length_b	100.640 Å
Unit-cell length c length_c	168.050 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	8

Space group space_group	P 21 21 21
Space-group number int_tables_number	19
Crystal system crystal_system	—

Resolution resolution	2.800 Å
Low-resolution limit resolution_low	20.000 Å
R factor r_factor	—
R_work r_work	0.2460
R_free r_free	0.2910

Crystal Structure of a Recombinant IgE Fab Fragment in Complex with Bovine Beta-Lactoglobulin Allergen

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

Beta-lactoglobulin

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

2r56__assembly_1__model_1

2r56__assembly_1__model_1 | I(q)

2r56__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 (4)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

Entity 3 Entity 3 polymer

Polymer Polymer

Entity 4 Entity 4 non-polymer

6. Fold Classification (SCOP + CATH) 18 domains

SCOP 2.08 (8 domains)

CATH v4.4 (10 domains)

7. Citations (1)

Crystal Structure of a Recombinant IgE Fab Fragment in Complex with Bovine Beta-Lactoglobulin Allergen

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

Beta-lactoglobulin

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

2r56__assembly_1__model_1

2r56__assembly_1__model_1 | I(q)

2r56__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 (4)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

Entity 3 Entity 3 polymer

Polymer Polymer

Entity 4 Entity 4 non-polymer

6. Fold Classification (SCOP + CATH) 18 domains

SCOP 2.08 (8 domains)

CATH v4.4 (10 domains)

7. Citations (1)