3ks0

Crystal structure of the heme domain of flavocytochrome b2 in complex with Fab B2B4

Method: X-RAY DIFFRACTION

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

Cytochrome b2, mitochondrial

Saccharomyces cerevisiae

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 3	heme domain of flavocytochrome b2 × 1 Fragment Antigen Binding B2B4 × 1 PROTOPORPHYRIN IX CONTAINING FE × 1 water × 3	Consistent with protein count
2	Protein heterocomplex	Heteromer	Protein 3	heme domain of flavocytochrome b2 × 1 Fragment Antigen Binding B2B4 × 1 PROTOPORPHYRIN IX CONTAINING FE × 1 water × 3	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	CYB2_YEAST
Isoform	—
PDB entities	3
Chains and sequence ranges	Author chain A； PDBConstruct 1–95； UniProt 86–180 Author chain B； PDBConstruct 1–95； UniProt 86–180

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	3ks0
Deposition date deposition_date	2009-11-20
Structure title title	Crystal structure of the heme domain of flavocytochrome b2 in complex with Fab B2B4
Keywords keywords	;electron transfer, epitope, domain mobility, flavocytochrome b2, antibody, Fab, heme domain, Electron transport, Flavoprotein, FMN, Heme, Metal-binding, Mitochondrion, Oxidoreductase, Respiratory chain, Transit peptide, Transport ;; OXIDOREDUCTASE
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.

3ks0__assembly_1__model_1

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

Download this curve (.dat)

3ks0__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

3ks0__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	28.18 Å
Rg (electron density)	27.81 Å
Total Rg	28.50 Å
Atom count	3944
Residues	518
Excluded volume	70091 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`3ks0__assembly_1__model_1`	trimeric （3）	Success	4.1.3-1-20251215 (887e7ef)	View Download
2	1	`3ks0__assembly_2__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 (5)

Entity 1 Entity 1 polymer

Description description	heme domain of flavocytochrome b2
Molecular weight formula_weight	22876.4 kDa
Source method src_method	nat
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	L,J
Atom count atom_count	8021

QAVVTQESALTTSPGETVTLTCRSSTGAVTTSNYANWVQEKPDHLFTGLIGGTNKRAPGVPARFSGSLIGDKAALTITGAQTEDEAIYFCALWDSNHLVFGGGTKLTVLGQPKSSPSVTLFPPSSEELETNKATLVCTITDFYPGVVTVDWKVDGTPVTQGMETTQPSKQSNNKYMASSYLTLTARAWERHSSYSCQVTHEGHTVEKSLSPADC

Entity 2 Entity 2 polymer

Description description	Fragment Antigen Binding B2B4
Molecular weight formula_weight	24475.3 kDa
Source method src_method	nat
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	H,K

EVQLQESGPSLVKPSQTLSLTCSVTGDSITSGYWNWIRKFPGNKLEYMGYISYGGSTYYNPSLESRISITRDTSKNQYYLQLNSVTTEDTATYFCARLFGSYYFDYWGQGTTLTVSSAKTTPPSVYPLAPGSAAQTNSMVTLGCLVKGYFPEPVTVTWNSGSLSSGVHTFPAVLQSDLYTLSSSVTVPSSTWPSETVTCNVAHPASSTKVDKKIVPRDCGCKPCI

Entity 3 Entity 3 polymer

Description description	Cytochrome b2, mitochondrial
Molecular weight formula_weight	10464.1 kDa
EC 编号 ec_number	1.1.2.3
Source method src_method	man
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,B

MNKQKISPAEVAKHNKPDDCWVVINGYVYDLTRFLPNHPGGQDVIKFNAGKDVTAIFEPLHAPNVIDKYIAPEKKLGPLQGSMPPELVCPPYAPG

Source Source

Source organism organism	Saccharomyces cerevisiae
Common name common_name	yeast
NCBI taxonomy ID ncbi_taxonomy_id	4932
Host organism host_organism	Escherichia coli

Entity 4 Entity 4 non-polymer

Description description	PROTOPORPHYRIN IX CONTAINING FE
Molecular weight formula_weight	616.5 kDa
Source method src_method	syn
Copy count entity_count	2

Entity 5 Entity 5 water

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	132

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6. Fold Classification (SCOP + CATH) 18 domains

SCOP 2.08 (8 domains)

Domain ID domain_id	d3ks0a_
Class class	d — Alpha and beta proteins (a+b)
Fold Fold fold	d.120 — Cytochrome b5-like heme/steroid binding domain
Superfamily Superfamily superfamily	d.120.1 — Cytochrome b5-like heme/steroid binding domain
Family Family family	d.120.1.0 — automated matches

Domain ID domain_id	d3ks0b_
Class class	d — Alpha and beta proteins (a+b)
Fold Fold fold	d.120 — Cytochrome b5-like heme/steroid binding domain
Superfamily Superfamily superfamily	d.120.1 — Cytochrome b5-like heme/steroid binding domain
Family Family family	d.120.1.0 — automated matches

Domain ID domain_id	d3ks0h_
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	d3ks0j1
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.1.1.0 — automated matches

Domain ID domain_id	d3ks0j2
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.1.1.0 — automated matches

Domain ID domain_id	d3ks0k_
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	d3ks0l1
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.1.1.0 — automated matches

Domain ID domain_id	d3ks0l2
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.1.1.0 — automated matches

CATH v4.4 (10 domains)

Domain ID domain_id	3ks0A00
Class class	3 — Alpha Beta
Architecture architecture	10 — Roll
Topology topology	120 — Flavocytochrome B2; Chain A, domain 1
Homologous superfamily homologous superfamily	10 — Cytochrome b5-like heme/steroid binding domain

Domain ID domain_id	3ks0B00
Class class	3 — Alpha Beta
Architecture architecture	10 — Roll
Topology topology	120 — Flavocytochrome B2; Chain A, domain 1
Homologous superfamily homologous superfamily	10 — Cytochrome b5-like heme/steroid binding domain

Domain ID domain_id	3ks0H01
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	3ks0H02
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	3ks0J01
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	3ks0J02
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	3ks0K01
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	3ks0K02
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	3ks0L01
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	3ks0L02
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	72.580 Å
Unit-cell length b length_b	83.680 Å
Unit-cell length c length_c	92.165 Å
Unit-cell angle α angle_alpha	90.00 °
Unit-cell angle β angle_beta	96.80 °
Unit-cell angle γ angle_gamma	90.00 °
Molecules per unit cell Z z_pdb	4

Space group space_group	P 1 21 1
Space-group number int_tables_number	4
Crystal system crystal_system	—

Resolution resolution	2.700 Å
Low-resolution limit resolution_low	24.750 Å
R factor r_factor	0.2177
R_work r_work	0.2140
R_free r_free	0.2891

Crystal structure of the heme domain of flavocytochrome b2 in complex with Fab B2B4

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

Cytochrome b2, mitochondrial

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

3ks0__assembly_1__model_1

3ks0__assembly_1__model_1 | I(q)

3ks0__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 (5)

Entity 1 Entity 1 polymer

Polymer Polymer

Entity 2 Entity 2 polymer

Polymer Polymer

Entity 3 Entity 3 polymer

Polymer Polymer

Source Source

Entity 4 Entity 4 non-polymer

Entity 5 Entity 5 water

6. Fold Classification (SCOP + CATH) 18 domains

SCOP 2.08 (8 domains)

CATH v4.4 (10 domains)

7. Citations (3)

Crystal structure of the heme domain of flavocytochrome b2 in complex with Fab B2B4

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

Cytochrome b2, mitochondrial

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

3ks0__assembly_1__model_1

3ks0__assembly_1__model_1 | I(q)

3ks0__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 (5)

Entity 1 Entity 1 polymer

Polymer Polymer

Entity 2 Entity 2 polymer

Polymer Polymer

Entity 3 Entity 3 polymer

Polymer Polymer

Source Source

Entity 4 Entity 4 non-polymer

Entity 5 Entity 5 water

6. Fold Classification (SCOP + CATH) 18 domains

SCOP 2.08 (8 domains)

CATH v4.4 (10 domains)

7. Citations (3)