2a73

Human Complement Component C3

Method: X-RAY DIFFRACTION

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

Complement C3

OrganismNot specified

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Other combination	Homooligomer	Protein 2 其他Polymer 2	2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose × 1 ;alpha-D-mannopyranose-(1-3)-[beta-D-mannopyranose-(1-6)]alpha-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose ; × 1	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	CO3_HUMAN
Isoform	—
PDB entities	1, 2
Chains and sequence ranges	Author chain A； PDBConstruct 1–643； UniProt 23–665 Author chain B； PDBConstruct 1–991； UniProt 673–1663

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	2a73
Deposition date deposition_date	2005-07-04
Structure title title	Human Complement Component C3
Keywords keywords	INTACT THIOESTER, 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.

2a73__assembly_1__model_1

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

Download this curve (.dat)

2a73__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

2a73__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	43.40 Å
Rg (electron density)	42.97 Å
Total Rg	43.15 Å
Atom count	12860
Residues	1611
Excluded volume	229670 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`2a73__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	Complement C3
Molecular weight formula_weight	71267.2 kDa
Source method src_method	nat
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A
Atom count atom_count	12860

SPMYSIITPNILRLESEETMVLEAHDAQGDVPVTVTVHDFPGKKLVLSSEKTVLTPATNHMGNVTFTIPANREFKSEKGRNKFVTVQATFGTQVVEKVVLVSLQSGYLFIQTDKTIYTPGSTVLYRIFTVNHKLLPVGRTVMVNIENPEGIPVKQDSLSSQNQLGVLPLSWDIPELVNMGQWKIRAYYENSPQQVFSTEFEVKEYVLPSFEVIVEPTEKFYYIYNEKGLEVTITARFLYGKKVEGTAFVIFGIQDGEQRISLPESLKRIPIEDGSGEVVLSRKVLLDGVQNLRAEDLVGKSLYVSATVILHSGSDMVQAERSGIPIVTSPYQIHFTKTPKYFKPGMPFDLMVFVTNPDGSPAYRVPVAVQGEDTVQSLTQGDGVAKLSINTHPSQKPLSITVRTKKQELSEAEQATRTMQALPYSTVGNSNNYLHLSVLRTELRPGETLNVNFLLRMDRAHEAKIRYYTYLIMNKGRLLKAGRQVREPGQDLVVLPLSITTDFIPSFRLVAYYTLIGASGQREVVADSVWVDVKDSCVGSLVVKSGQSEDRQPVPGQQMTLKIEGDHGARVVLVAVDKGVFVLNKKNKLTQSKIWDVVEKADIGCTPGSGKDYAGVFSDAGLTFTSSSGQQTAQRAELQCPQP

Entity 2 Entity 2 polymer

Description description	Complement C3
Molecular weight formula_weight	113082.8 kDa
Source method src_method	nat
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	B

VQLTEKRMDKVGKYPKELRKCCEDGMRENPMRFSCQRRTRFISLGEACKKVFLDCCNYITELRRQHARASHLGLARSNLDEDIIAEENIVSRSEFPESWLWNVEDLKEPPKNGISTKLMNIFLKDSITTWEILAVSMSDKKGICVADPFEVTVMQDFFIDLRLPYSVVRNEQVEIRAVLYNYRQNQELKVRVELLHNPAFCSLATTKRRHQQTVTIPPKSSLSVPYVIVPLKTGLQEVEVKAAVYHHFISDGVRKSLKVVPEGIRMNKTVAVRTLDPERLGREGVQKEDIPPADLSDQVPDTESETRILLQGTPVAQMTEDAVDAERLKHLIVTPSGCGEQNMIGMTPTVIAVHYLDETEQWEKFGLEKRQGALELIKKGYTQQLAFRQPSSAFAAFVKRAPSTWLTAYVVKVFSLAVNLIAIDSQVLCGAVKWLILEKQKPDGVFQEDAPVIHQEMIGGLRNNNEKDMALTAFVLISLQEAKDICEEQVNSLPGSITKAGDFLEANYMNLQRSYTVAIAGYALAQMGRLKGPLLNKFLTTAKDKNRWEDPGKQLYNVEATSYALLALLQLKDFDFVPPVVRWLNEQRYYGGGYGSTQATFMVFQALAQYQKDAPDHQELNLDVSLQLPSRSSKITHRIHWESASLLRSEETKENEGFTVTAEGKGQGTLSVVTMYHAKAKDQLTCNKFDLKVTIKPAPETEKRPQDAKNTMILEICTRYRGDQDATMSILDISMMTGFAPDTDDLKQLANGVDRYISKYELDKAFSDRNTLIIYLDKVSHSEDDCLAFKVHQYFNVELIQPGAVKVYAYYNLEESCTRFYHPEKEDGKLNKLCRDELCRCAEENCFIQKSDDKVTLEERLDKACEPGVDYVYKTRLVKVQLSNDFDEYIMAIEQTIKSGSDEVQVGQQRTFISPIKCREALKLEEKKHYLMWGLSSDFWGEKPNLSYIIGKDTWVEHWPEEDECQDEENQKQCQDLGAFTESMVVFGCPN

Entity 3 Entity 3 branched

Description description	2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose
Molecular weight formula_weight	424.4 kDa
Source method src_method	man
Copy count entity_count	1

Entity 4 Entity 4 branched

Description description	;alpha-D-mannopyranose-(1-3)-[beta-D-mannopyranose-(1-6)]alpha-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose ;
Molecular weight formula_weight	910.8 kDa
Source method src_method	man
Copy count entity_count	1

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6. Fold Classification (SCOP + CATH) 28 domains

SCOP 2.08 (15 domains)

Domain ID domain_id	d2a73.1
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.29 — Macroglobulin
Family Family family	b.1.29.7 — Complement C3 MG6-like

Domain ID domain_id	d2a73a1
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.29 — Macroglobulin
Family Family family	b.1.29.2 — Complement C3 MG1-like

Domain ID domain_id	d2a73a2
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.29 — Macroglobulin
Family Family family	b.1.29.3 — Complement C3 MG2-like

Domain ID domain_id	d2a73a3
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.29 — Macroglobulin
Family Family family	b.1.29.4 — Complement C3 MG3-like

Domain ID domain_id	d2a73a4
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.29 — Macroglobulin
Family Family family	b.1.29.5 — Complement C3 MG4-like

Domain ID domain_id	d2a73a5
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.29 — Macroglobulin
Family Family family	b.1.29.6 — Complement C3 MG5-like

Domain ID domain_id	d2a73a6
Class class	g — Small proteins
Fold Fold fold	g.94 — Complement C3 linker domain-like
Superfamily Superfamily superfamily	g.94.1 — Complement C3 linker domain-like
Family Family family	g.94.1.1 — Complement C3 linker domain-like

Domain ID domain_id	d2a73b1
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.29 — Macroglobulin
Family Family family	b.1.29.8 — Complement C3 MG7-like

Domain ID domain_id	d2a73b2
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.29 — Macroglobulin
Family Family family	b.1.29.1 — Alpha-macroglobulin receptor domain

Domain ID domain_id	d2a73b3
Class class	a — All alpha proteins
Fold Fold fold	a.50 — Anaphylotoxins (complement system)
Superfamily Superfamily superfamily	a.50.1 — Anaphylotoxins (complement system)
Family Family family	a.50.1.1 — Anaphylotoxins (complement system)

Domain ID domain_id	d2a73b4
Class class	j — Peptides
Fold Fold fold	j.127 — Complement system alpha-prime linker
Superfamily Superfamily superfamily	j.127.1 — Complement system alpha-prime linker
Family Family family	j.127.1.1 — Complement system alpha-prime linker

Domain ID domain_id	d2a73b5
Class class	j — Peptides
Fold Fold fold	j.128 — Complement system anchor region
Superfamily Superfamily superfamily	j.128.1 — Complement system anchor region
Family Family family	j.128.1.1 — Complement system anchor region

Domain ID domain_id	d2a73b6
Class class	b — All beta proteins
Fold Fold fold	b.23 — CUB-like
Superfamily Superfamily superfamily	b.23.4 — Complement system CUB domain
Family Family family	b.23.4.1 — Complement system CUB domain

Domain ID domain_id	d2a73b7
Class class	a — All alpha proteins
Fold Fold fold	a.102 — alpha/alpha toroid
Superfamily Superfamily superfamily	a.102.4 — Terpenoid cyclases/Protein prenyltransferases
Family Family family	a.102.4.4 — Complement components

Domain ID domain_id	d2a73b8
Class class	b — All beta proteins
Fold Fold fold	b.40 — OB-fold
Superfamily Superfamily superfamily	b.40.3 — TIMP-like
Family Family family	b.40.3.3 — Netrin-like domain (NTR/C345C module)

CATH v4.4 (13 domains)

Domain ID domain_id	2a73A01
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	1930 — Macroglobulin (MG2) domain

Domain ID domain_id	2a73A02
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	1930 — Macroglobulin (MG2) domain

Domain ID domain_id	2a73A03
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	1940 —

Domain ID domain_id	2a73A04
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	2a73A05
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	1930 — Macroglobulin (MG2) domain

Domain ID domain_id	2a73A06
Class class	6 — Special
Architecture architecture	20 — Other non-globular
Topology topology	50 — N-terminal domain of TfIIb
Homologous superfamily homologous superfamily	160 —

Domain ID domain_id	2a73B01
Class class	1 — Mainly Alpha
Architecture architecture	20 — Up-down Bundle
Topology topology	91 — Influenza Virus Matrix Protein; Chain A, domain 1
Homologous superfamily homologous superfamily	20 — Anaphylotoxins (complement system)

Domain ID domain_id	2a73B02
Class class	2 — Mainly Beta
Architecture architecture	20 — Single Sheet
Topology topology	130 — S-adenosyl-L-methionine-dependent methyltransferases
Homologous superfamily homologous superfamily	20 —

Domain ID domain_id	2a73B03
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	2a73B04
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	120 — Jelly Rolls
Homologous superfamily homologous superfamily	1540 —

Domain ID domain_id	2a73B05
Class class	1 — Mainly Alpha
Architecture architecture	50 — Alpha/alpha barrel
Topology topology	10 — Glycosyltransferase
Homologous superfamily homologous superfamily	20 —

Domain ID domain_id	2a73B06
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	690 — Alpha-macroglobulin, receptor-binding domain

Domain ID domain_id	2a73B07
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	50 — OB fold (Dihydrolipoamide Acetyltransferase, E2P)
Homologous superfamily homologous superfamily	120 —

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Unit-cell length a length_a	116.980 Å
Unit-cell length b length_b	156.260 Å
Unit-cell length c length_c	271.200 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	I 2 2 2
Space-group number int_tables_number	23
Crystal system crystal_system	—

Resolution resolution	3.300 Å
Low-resolution limit resolution_low	40.000 Å
R factor r_factor	0.2330
R_work r_work	0.2301
R_free r_free	0.2894

Human Complement Component C3

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

Complement C3

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

2a73__assembly_1__model_1

2a73__assembly_1__model_1 | I(q)

2a73__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

Entity 2 Entity 2 polymer

Polymer Polymer

Entity 3 Entity 3 branched

Entity 4 Entity 4 branched

6. Fold Classification (SCOP + CATH) 28 domains

SCOP 2.08 (15 domains)

CATH v4.4 (13 domains)

7. Citations (1)

Human Complement Component C3

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

Complement C3

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

2a73__assembly_1__model_1

2a73__assembly_1__model_1 | I(q)

2a73__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

Entity 2 Entity 2 polymer

Polymer Polymer

Entity 3 Entity 3 branched

Entity 4 Entity 4 branched

6. Fold Classification (SCOP + CATH) 28 domains

SCOP 2.08 (15 domains)

CATH v4.4 (13 domains)

7. Citations (1)