SAXSdb — 1iv5

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

CD81 antigen

Homo sapiens

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein homooligomer	Homooligomer	Protein 2	water × 2	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	CD81_HUMAN
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–89； UniProt 113–201 Author chain B； PDBConstruct 1–89； UniProt 113–201

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	1iv5
Deposition date deposition_date	2002-03-14
Structure title title	New Crystal Form of Human CD81 Large Extracellular Loop.
Keywords keywords	Alpha domain, Five Helix, 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.

1iv5__assembly_1__model_1

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

Download this curve (.dat)

1iv5__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

1iv5__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	17.40 Å
Rg (electron density)	16.67 Å
Total Rg	17.65 Å
Atom count	1388
Residues	180
Excluded volume	24492 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`1iv5__assembly_1__model_1`	dimeric （2）	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 (2)

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6. Fold Classification (SCOP + CATH) 6 domains

SCOP 2.08 (4 domains)

Domain ID domain_id	d1iv5a1
Class class	a — All alpha proteins
Fold Fold fold	a.135 — Tetraspanin
Superfamily Superfamily superfamily	a.135.1 — Tetraspanin
Family Family family	a.135.1.1 — Tetraspanin

Domain ID domain_id	d1iv5a2
Class class	l — Artifacts
Fold Fold fold	l.1 — Tags
Superfamily Superfamily superfamily	l.1.1 — Tags
Family Family family	l.1.1.1 — Tags

Domain ID domain_id	d1iv5b1
Class class	a — All alpha proteins
Fold Fold fold	a.135 — Tetraspanin
Superfamily Superfamily superfamily	a.135.1 — Tetraspanin
Family Family family	a.135.1.1 — Tetraspanin

Domain ID domain_id	d1iv5b2
Class class	l — Artifacts
Fold Fold fold	l.1 — Tags
Superfamily Superfamily superfamily	l.1.1 — Tags
Family Family family	l.1.1.1 — Tags

CATH v4.4 (2 domains)

Domain ID domain_id	1iv5A00
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	1450 — Cd81 Antigen, Extracellular Domain; Chain: A
Homologous superfamily homologous superfamily	10 — Tetraspanin

Domain ID domain_id	1iv5B00
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	1450 — Cd81 Antigen, Extracellular Domain; Chain: A
Homologous superfamily homologous superfamily	10 — Tetraspanin

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Unit-cell length a length_a	102.052 Å
Unit-cell length b length_b	102.052 Å
Unit-cell length c length_c	35.283 Å
Unit-cell angle α angle_alpha	90.00 °
Unit-cell angle β angle_beta	90.00 °
Unit-cell angle γ angle_gamma	120.00 °
Molecules per unit cell Z z_pdb	12

Space group space_group	P 64
Space-group number int_tables_number	172
Crystal system crystal_system	—

Resolution resolution	2.600 Å
Low-resolution limit resolution_low	18.730 Å
R factor r_factor	0.2338
R_work r_work	0.2287
R_free r_free	0.2822

Description description	CD81 antigen
Molecular weight formula_weight	9917.1 kDa
Source method src_method	man
Copy count entity_count	2

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,B
Atom count atom_count	1403

New Crystal Form of Human CD81 Large Extracellular Loop.

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

CD81 antigen

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

1iv5__assembly_1__model_1

1iv5__assembly_1__model_1 | I(q)

1iv5__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 (2)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 water

6. Fold Classification (SCOP + CATH) 6 domains

SCOP 2.08 (4 domains)

CATH v4.4 (2 domains)

7. Citations (1)

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

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	15

New Crystal Form of Human CD81 Large Extracellular Loop.

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

CD81 antigen

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

1iv5__assembly_1__model_1

1iv5__assembly_1__model_1 | I(q)

1iv5__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 (2)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 water

6. Fold Classification (SCOP + CATH) 6 domains

SCOP 2.08 (4 domains)

CATH v4.4 (2 domains)

7. Citations (1)