SAXSdb — 3f31

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

Spectrin alpha chain, brain

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
2	Protein monomer	Monomer	Protein 1	water × 1	Consistent with protein count
3	Protein monomer	Monomer	Protein 1	water × 1	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	SPTA2_HUMAN
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 3–149； UniProt 1–147 Author chain B； PDBConstruct 3–149； UniProt 1–147

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	3f31
Deposition date deposition_date	2008-10-30
Structure title title	Crystal Structure of the N-terminal region of AlphaII-spectrin Tetramerization Domain
Keywords keywords	;lone helix followed by a triple helical bundle, Actin capping, Actin-binding, Alternative splicing, Calcium, Calmodulin-binding, Cytoplasm, Cytoskeleton, Phosphoprotein, Polymorphism, SH3 domain, SPECTRIN, ACTIN BINDING, STRUCTURAL PROTEIN ;; ACTIN BINDING, STRUCTURAL PROTEIN
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.

3f31__assembly_1__model_1

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

Download this curve (.dat)

3f31__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

3f31__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	26.55 Å
Rg (electron density)	26.37 Å
Total Rg	26.98 Å
Atom count	2322
Residues	277
Excluded volume	41000 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`3f31__assembly_1__model_1`	dimeric （2）	Success	4.1.3-1-20251215 (887e7ef)	View Download
2	1	`3f31__assembly_2__model_1`	monomeric （1）	Success	4.1.3-1-20251215 (887e7ef)	View Download
3	1	`3f31__assembly_3__model_1`	monomeric （1）	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) 4 domains

SCOP 2.08 (2 domains)

Domain ID domain_id	d3f31a_
Class class	a — All alpha proteins
Fold Fold fold	a.7 — Spectrin repeat-like
Superfamily Superfamily superfamily	a.7.1 — Spectrin repeat
Family Family family	a.7.1.0 — automated matches

Domain ID domain_id	d3f31b_
Class class	a — All alpha proteins
Fold Fold fold	a.7 — Spectrin repeat-like
Superfamily Superfamily superfamily	a.7.1 — Spectrin repeat
Family Family family	a.7.1.0 — automated matches

CATH v4.4 (2 domains)

Domain ID domain_id	3f31A00
Class class	1 — Mainly Alpha
Architecture architecture	20 — Up-down Bundle
Topology topology	58 — Methane Monooxygenase Hydroxylase; Chain G, domain 1
Homologous superfamily homologous superfamily	60 —

Domain ID domain_id	3f31B00
Class class	1 — Mainly Alpha
Architecture architecture	20 — Up-down Bundle
Topology topology	58 — Methane Monooxygenase Hydroxylase; Chain G, domain 1
Homologous superfamily homologous superfamily	60 —

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Unit-cell length a length_a	57.720 Å
Unit-cell length b length_b	71.460 Å
Unit-cell length c length_c	80.810 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	2.300 Å
Low-resolution limit resolution_low	18.984 Å
R factor r_factor	0.2200
R_work r_work	0.2140
R_free r_free	0.2798

Description description	Spectrin alpha chain, brain
Molecular weight formula_weight	17691.0 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	2570

Crystal Structure of the N-terminal region of AlphaII-spectrin Tetramerization Domain

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

Spectrin alpha chain, brain

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

3f31__assembly_1__model_1

3f31__assembly_1__model_1 | I(q)

3f31__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) 4 domains

SCOP 2.08 (2 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	206

Crystal Structure of the N-terminal region of AlphaII-spectrin Tetramerization Domain

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

Spectrin alpha chain, brain

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

3f31__assembly_1__model_1

3f31__assembly_1__model_1 | I(q)

3f31__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) 4 domains

SCOP 2.08 (2 domains)

CATH v4.4 (2 domains)

7. Citations (1)