SAXSdb — 4iw4

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

Ecotin

OrganismNot specified

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 4	Mannan-binding lectin serine protease 3 × 2 （P48740） water × 2	Consistent with protein count
2	Protein heterocomplex	Heteromer	Protein 8	Mannan-binding lectin serine protease 3 × 4 （P48740） water × 4	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	ECOT_ECOLI
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain C； PDBConstruct 1–142； UniProt 21–162 Author chain D； PDBConstruct 1–142； UniProt 21–162

Mannan-binding lectin serine protease 3

Homo sapiens

UniProt P48740

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 4	Ecotin × 2 （P23827） water × 2	Consistent with protein count
2	Protein heterocomplex	Heteromer	Protein 8	Ecotin × 4 （P23827） water × 4	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	MASP1_HUMAN
Isoform	—
PDB entities	2
Chains and sequence ranges	Author chain E； PDBConstruct 1–279； UniProt 450–728 Author chain F； PDBConstruct 1–279； UniProt 450–728

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	4iw4
Deposition date deposition_date	2013-01-23
Structure title title	Crystal structure of the serine protease domain of MASP-3 in complex with ecotin
Keywords keywords	trypsin-like fold, protease, inhibitor, extracellular, HYDROLASE-HYDROLASE INHIBITOR complex; HYDROLASE/HYDROLASE INHIBITOR
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.

4iw4__assembly_1__model_1

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

Download this curve (.dat)

4iw4__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

4iw4__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	30.69 Å
Rg (electron density)	30.47 Å
Total Rg	31.06 Å
Atom count	5731
Residues	755
Excluded volume	102150 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`4iw4__assembly_1__model_1`	tetrameric （4）	Success	4.1.3-1-20251215 (887e7ef)	View Download
2	1	`4iw4__assembly_2__model_1`	octameric （8）	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 (3)

Entity 1 Entity 1 polymer

Description description	Ecotin
Molecular weight formula_weight	16120.5 kDa
Source method src_method	nat
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	C,D
Atom count atom_count	5735

AESVQPLEKIAPYPQAEKGMKRQVIQLTPQEDESTLKVELLIGQTLEVDCNLHRLGGKLENKTLEGWGYDYYVFDKVSSPVSTMMACPDGKKEKKFVTAYLGDAGMLRYNSKLPIVVYTPDNVDVKYRVWKAEEKIDNAVVR

Entity 2 Entity 2 polymer

Description description	Mannan-binding lectin serine protease 3
Molecular weight formula_weight	30584.5 kDa
Source method src_method	man
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	E,F

IIGGRNAEPGLFPWQALIVVEDTSRVPNDKWFGSGALLSASWILTAAHVLRSQRRDTTVIPVSKEHVTVYLGLHDVRDKSGAVNSSAARVVLHPDFNIQNYNHDIALVQLQEPVPLGPHVMPVCLPRLEPEGPAPHMLGLVAGWGISNPNVTVDEIISSGTRTLSDVLQYVKLPVVPHAECKTSYESRSGNYSVTENMFCAGYYEGGKDTCLGDSGGAFVIFDDLSQRWVVQGLVSWGGPEECGSKQVYGVYTKVSNYVDWVWEQMGLPQSVVEPQVER

Source Source

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

Entity 3 Entity 3 water

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	4

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6. Fold Classification (SCOP + CATH) 6 domains

CATH v4.4 (6 domains)

Domain ID domain_id	4iw4C00
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	550 — Ecotin

Domain ID domain_id	4iw4D00
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	550 — Ecotin

Domain ID domain_id	4iw4E01
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	10 — Thrombin, subunit H
Homologous superfamily homologous superfamily	10 — Trypsin-like serine proteases

Domain ID domain_id	4iw4E02
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	10 — Thrombin, subunit H
Homologous superfamily homologous superfamily	10 — Trypsin-like serine proteases

Domain ID domain_id	4iw4F01
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	10 — Thrombin, subunit H
Homologous superfamily homologous superfamily	10 — Trypsin-like serine proteases

Domain ID domain_id	4iw4F02
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	10 — Thrombin, subunit H
Homologous superfamily homologous superfamily	10 — Trypsin-like serine proteases

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Unit-cell length a length_a	66.720 Å
Unit-cell length b length_b	164.620 Å
Unit-cell length c length_c	90.650 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 2
Space-group number int_tables_number	18
Crystal system crystal_system	—

Resolution resolution	3.200 Å
Low-resolution limit resolution_low	19.980 Å
R factor r_factor	0.2109
R_work r_work	0.2078
R_free r_free	0.2691

Crystal structure of the serine protease domain of MASP-3 in complex with ecotin

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

Ecotin

State in the Current Structure

Other States of the Same Protein in the Database

Mannan-binding lectin serine protease 3

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

4iw4__assembly_1__model_1

4iw4__assembly_1__model_1 | I(q)

4iw4__assembly_1__model_1 | P(r) · Pending

4. Crystallography and Experiment 4. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

Refinement Refinement

5. Entities and Polymers Entities & Polymers (3)

Entity 1 Entity 1 polymer

Polymer Polymer

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

Entity 3 Entity 3 water

6. Fold Classification (SCOP + CATH) 6 domains

CATH v4.4 (6 domains)

7. Citations (1)

Crystal structure of the serine protease domain of MASP-3 in complex with ecotin

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

Ecotin

State in the Current Structure

Other States of the Same Protein in the Database

Monomer

Homodimer

Homotetramer

Other homooligomers

Heteromeric or nucleic-acid complex

Mannan-binding lectin serine protease 3

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

4iw4__assembly_1__model_1

4iw4__assembly_1__model_1 | I(q)

4iw4__assembly_1__model_1 | P(r) · Pending

4. Crystallography and Experiment 4. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

Refinement Refinement

5. Entities and Polymers Entities & Polymers (3)

Entity 1 Entity 1 polymer

Polymer Polymer

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

Entity 3 Entity 3 water

6. Fold Classification (SCOP + CATH) 6 domains

CATH v4.4 (6 domains)

7. Citations (1)