SAXSdb — 4i1n

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

Dihydrofolate reductase

Escherichia coli

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 2	Protein ca1697 (nanobody) × 1 FOLIC ACID × 1 water × 2	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	DYR_ECOLI
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–159； UniProt 1–159

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	4i1n
Deposition date deposition_date	2012-11-21
Structure title title	R104A-ca1697 nanobody binding to the binary DHFR.folate complex
Keywords keywords	alpha/beta fold, immunoglobulin fold, reductase, NADPH, folate derivatives, hydride transfer, OXIDOREDUCTASE-IMMUNE SYSTEM complex; OXIDOREDUCTASE/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.

4i1n__assembly_1__model_1

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

Download this curve (.dat)

4i1n__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

4i1n__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	21.80 Å
Rg (electron density)	20.96 Å
Total Rg	21.78 Å
Atom count	2265
Residues	287
Excluded volume	39914 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`4i1n__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 (4)

Entity 1 Entity 1 polymer

Description description	Dihydrofolate reductase
Molecular weight formula_weight	18019.3 kDa
EC 编号 ec_number	1.5.1.3
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A
Atom count atom_count	2585

MISLIAALAVDRVIGMENAMPWNLPADLAWFKRNTLNKPVIMGRHTWESIGRPLPGRKNIILSSQPGTDDRVTWVKSVDEAIAACGDVPEIMVIGGGRVYEQFLPKAQKLYLTHIDAEVEGDTHFPDYEPDDWESVFSEFHDADAQNSHSYCFEILERR

Source Source

Source organism organism	Escherichia coli
NCBI taxonomy ID ncbi_taxonomy_id	83333
Host organism host_organism	Escherichia coli

Entity 2 Entity 2 polymer

Description description	Protein ca1697 (nanobody)
Molecular weight formula_weight	14740.5 kDa
Mutation mutation	R104A
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	B

QVQLQESGGGLVQAGASLRLSCAASERLTVDYAIGWFRQAPGKEREFVAAISWGGGLTVYGESVEGRFTISRDIAKNTMNLQMNVLRPEDTANYYCAASRISYAVWNTIPYNKLTLWGRGTQVTVSSHHHHHH

Source Source

Source organism organism	lama glama
NCBI taxonomy ID ncbi_taxonomy_id	9844
Host organism host_organism	Escherichia coli

Entity 3 Entity 3 non-polymer

Description description	FOLIC ACID
Molecular weight formula_weight	441.4 kDa
Source method src_method	syn
Copy count entity_count	1

Entity 4 Entity 4 water

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	302

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6. Fold Classification (SCOP + CATH) 5 domains

SCOP 2.08 (3 domains)

Domain ID domain_id	d4i1na_
Class class	c — Alpha and beta proteins (a/b)
Fold Fold fold	c.71 — Dihydrofolate reductase-like
Superfamily Superfamily superfamily	c.71.1 — Dihydrofolate reductase-like
Family Family family	c.71.1.1 — Dihydrofolate reductases

Domain ID domain_id	d4i1nb1
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	d4i1nb2
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	4i1nA00
Class class	3 — Alpha Beta
Architecture architecture	40 — 3-Layer(aba) Sandwich
Topology topology	430 — Dihydrofolate Reductase, subunit A
Homologous superfamily homologous superfamily	10 — Dihydrofolate Reductase, subunit A

Domain ID domain_id	4i1nB00
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	49.267 Å
Unit-cell length b length_b	55.642 Å
Unit-cell length c length_c	119.213 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	4

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

Resolution resolution	1.888 Å
Low-resolution limit resolution_low	19.596 Å
R factor r_factor	0.1793
R_work r_work	0.1773
R_free r_free	0.2139

R104A-ca1697 nanobody binding to the binary DHFR.folate complex

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

Dihydrofolate reductase

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

4i1n__assembly_1__model_1

4i1n__assembly_1__model_1 | I(q)

4i1n__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

Source Source

Entity 3 Entity 3 non-polymer

Entity 4 Entity 4 water

6. Fold Classification (SCOP + CATH) 5 domains

SCOP 2.08 (3 domains)

CATH v4.4 (2 domains)

7. Citations (1)

R104A-ca1697 nanobody binding to the binary DHFR.folate complex

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

Dihydrofolate reductase

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

4i1n__assembly_1__model_1

4i1n__assembly_1__model_1 | I(q)

4i1n__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

Source Source

Entity 3 Entity 3 non-polymer

Entity 4 Entity 4 water

6. Fold Classification (SCOP + CATH) 5 domains

SCOP 2.08 (3 domains)

CATH v4.4 (2 domains)

7. Citations (1)