SAXSdb — 8w18

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

Plasma protease C1 inhibitor

Homo sapiens

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 3	Complement C1s subcomponent light chain × 1 （P09871） Complement C1s subcomponent heavy chain × 1 （P09871）	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	IC1_HUMAN
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain I； PDBConstruct 6–395； UniProt 111–500

Complement C1s subcomponent light chain

Homo sapiens

UniProt P09871

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 3	Plasma protease C1 inhibitor × 1 （P05155）	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	C1S_HUMAN
Isoform	—
PDB entities	2, 3
Chains and sequence ranges	Author chain B； PDBConstruct 1–251； UniProt 438–688 Author chain A； PDBConstruct 6–151； UniProt 292–437

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	8w18
Deposition date deposition_date	2024-02-15
Structure title title	The crystal structure of the Michaelis-Menten complex of a C1s/C1-INH at 3.94 Angstroms
Keywords keywords	complement, C1s, C1 esterase inhibitor, Michaelis complex, reactive center loop, exosite, 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.

8w18__assembly_1__model_1

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

Download this curve (.dat)

8w18__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

8w18__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	37.37 Å
Rg (electron density)	37.13 Å
Total Rg	37.41 Å
Atom count	6029
Residues	773
Excluded volume	107810 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`8w18__assembly_1__model_1`	trimeric （3）	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	Plasma protease C1 inhibitor
Molecular weight formula_weight	43997.4 kDa
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	I
Atom count atom_count	6029

GSTGSTDSPTQPTTGSFCPGPVTLCSDLESHSTEAVLGDALVDFSLKLYHAFSAMKKVETNMAFSPFSIASLLTQVLLGAGENTKTNLESILSYPKDFTCVHQALKGFTTKGVTSVSQIFHSPDLAIRDTFVNASRTLYSSSPRVLSNNSDANLELINTWVAKNTNNKISRLLDSLPSDTRLVLLNAIYLSAKWKTTFDPKKTRMEPFHFKNSVIKVPMMNSKKYPVAHFIDQTLKAKVGQLQLSHNLSLVILVPQNLKHRLEDMEQALSPSVFKAIMEKLEMSKFQPTLLTLPRIKVTTSQDMLSIMEKLEFFDFSYDLNLCGLTEDPDLQVSAMQHQTVLELTETGVEAAAASAISVARTLLVFEVQQPFLFVLWDQQHKFPVFMGRVYDPRA

Source Source

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

Entity 2 Entity 2 polymer

Description description	Complement C1s subcomponent light chain
Molecular weight formula_weight	27668.5 kDa
Mutation mutation	S632A
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	B

IIGGSDADIKNFPWQVFFDNPWAGGALINEYWVLTAAHVVEGNREPTMYVGSTSVQTSRLAKSKMLTPEHVFIHPGWKLLEVPEGRTNFDNDIALVRLKDPVKMGPTVSPICLPGTSSDYNLMDGDLGLISGWGRTEKRDRAVRLKAARLPVAPLRKCKEVKVEKPTADAEAYVFTPNMICAGGEKGMDSCKGDAGGAFAVQDPNDKTKFYAAGLVSWGPQCGTYGLYTRVKNYVDWIMKTMQENSTPRED

Source Source

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

Entity 3 Entity 3 polymer

Description description	Complement C1s subcomponent heavy chain
Molecular weight formula_weight	16588.5 kDa
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A

GSTGSMPCPKEDTPNSVWEPAKAKYVFRDVVQITCLDGFEVVEGRVGATSFYSTCQSNGKWSNSKLKCQPVDCGIPESIENGKVEDPESTLFGSVIRYTCEEPYYYMENGGGGEYHCAGNGSWVNEVLGPELPKCVPVCGVPREPFEEKQR

Source Source

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

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Unit-cell length a length_a	168.628 Å
Unit-cell length b length_b	168.628 Å
Unit-cell length c length_c	88.342 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 42 21 2
Space-group number int_tables_number	94
Crystal system crystal_system	tetragonal

Resolution resolution	3.940 Å
Low-resolution limit resolution_low	47.420 Å
R factor r_factor	0.2639
R_work r_work	0.2620
R_free r_free	0.2807

The crystal structure of the Michaelis-Menten complex of a C1s/C1-INH at 3.94 Angstroms

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

Plasma protease C1 inhibitor

State in the Current Structure

Other States of the Same Protein in the Database

Complement C1s subcomponent light chain

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

8w18__assembly_1__model_1

8w18__assembly_1__model_1 | I(q)

8w18__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 (3)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

Entity 3 Entity 3 polymer

Polymer Polymer

Source Source

7. Citations (1)

The crystal structure of the Michaelis-Menten complex of a C1s/C1-INH at 3.94 Angstroms

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

Plasma protease C1 inhibitor

State in the Current Structure

Other States of the Same Protein in the Database

Monomer

Homodimer

Homotetramer

Other homooligomers

Heteromeric or nucleic-acid complex

Complement C1s subcomponent light chain

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

8w18__assembly_1__model_1

8w18__assembly_1__model_1 | I(q)

8w18__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 (3)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

Entity 3 Entity 3 polymer

Polymer Polymer

Source Source

7. Citations (1)