1xbt

Crystal Structure of Human Thymidine Kinase 1

Method: X-RAY DIFFRACTION

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

Thymidine kinase, cytosolic

Homo sapiens

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein homooligomer	Homooligomer	Protein 4	ZINC ION × 4 MAGNESIUM ION × 4 THYMIDINE-5'-TRIPHOSPHATE × 4 water × 4	Consistent with protein count
2	Protein homooligomer	Homooligomer	Protein 4	ZINC ION × 4 MAGNESIUM ION × 4 THYMIDINE-5'-TRIPHOSPHATE × 4 water × 4	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	KITH_HUMAN
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–193； UniProt 1–193 Author chain B； PDBConstruct 1–193； UniProt 1–193 Author chain C； PDBConstruct 1–193； UniProt 1–193 Author chain D； PDBConstruct 1–193； UniProt 1–193 Author chain E； PDBConstruct 1–193； UniProt 1–193 Author chain F； PDBConstruct 1–193； UniProt 1–193 Author chain G； PDBConstruct 1–193； UniProt 1–193 Author chain H； PDBConstruct 1–193； UniProt 1–193

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	1xbt
Deposition date deposition_date	2004-08-31
Structure title title	Crystal Structure of Human Thymidine Kinase 1
Keywords keywords	DEOXYRIBONUCLEOSIDE KINASE, ZINC-BINDING DOMAIN, FEEDBACK INHIBITOR, Transferase; TRANSFERASE
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.

1xbt__assembly_1__model_1

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

Download this curve (.dat)

1xbt__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

1xbt__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	25.28 Å
Rg (electron density)	24.45 Å
Total Rg	25.30 Å
Atom count	5098
Residues	642
Excluded volume	91949 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`1xbt__assembly_1__model_1`	tetrameric （4）	Success	4.1.3-1-20251215 (887e7ef)	View Download
2	1	`1xbt__assembly_2__model_1`	tetrameric （4）	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	Thymidine kinase, cytosolic
Molecular weight formula_weight	21327.0 kDa
EC 编号 ec_number	2.7.1.21
Source method src_method	man
Copy count entity_count	8

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,B,C,D,E,F,G,H
Atom count atom_count	10451

MSCINLPTVLPGSPSKTRGQIQVILGPMFSGKSTELMRRVRRFQIAQYKCLVIKYAKDTRYSSSFCTHDRNTMEALPACLLRDVAQEALGVAVIGIDEGQFFPDIVEFCEAMANAGKTVIVAALDGTFQRKPFGAILNLVPLAESVVKLTAVCMECFREAAYTKRLGTEKEVEVIGGADKYHSVCRLCYFKKA

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 non-polymer

Description description	ZINC ION
Molecular weight formula_weight	65.4 kDa
Source method src_method	syn
Copy count entity_count	8

Entity 3 Entity 3 non-polymer

Description description	MAGNESIUM ION
Molecular weight formula_weight	24.3 kDa
Source method src_method	syn
Copy count entity_count	8

Entity 4 Entity 4 non-polymer

Description description	THYMIDINE-5'-TRIPHOSPHATE
Molecular weight formula_weight	482.2 kDa
Source method src_method	syn
Copy count entity_count	8

Entity 5 Entity 5 water

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	213

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6. Fold Classification (SCOP + CATH) 32 domains

SCOP 2.08 (16 domains)

Domain ID domain_id	d1xbta1
Class class	c — Alpha and beta proteins (a/b)
Fold Fold fold	c.37 — P-loop containing nucleoside triphosphate hydrolases
Superfamily Superfamily superfamily	c.37.1 — P-loop containing nucleoside triphosphate hydrolases
Family Family family	c.37.1.24 — Type II thymidine kinase

Domain ID domain_id	d1xbta2
Class class	g — Small proteins
Fold Fold fold	g.39 — Glucocorticoid receptor-like (DNA-binding domain)
Superfamily Superfamily superfamily	g.39.1 — Glucocorticoid receptor-like (DNA-binding domain)
Family Family family	g.39.1.14 — Type II thymidine kinase zinc finger

Domain ID domain_id	d1xbtb1
Class class	c — Alpha and beta proteins (a/b)
Fold Fold fold	c.37 — P-loop containing nucleoside triphosphate hydrolases
Superfamily Superfamily superfamily	c.37.1 — P-loop containing nucleoside triphosphate hydrolases
Family Family family	c.37.1.24 — Type II thymidine kinase

Domain ID domain_id	d1xbtb2
Class class	g — Small proteins
Fold Fold fold	g.39 — Glucocorticoid receptor-like (DNA-binding domain)
Superfamily Superfamily superfamily	g.39.1 — Glucocorticoid receptor-like (DNA-binding domain)
Family Family family	g.39.1.14 — Type II thymidine kinase zinc finger

Domain ID domain_id	d1xbtc1
Class class	c — Alpha and beta proteins (a/b)
Fold Fold fold	c.37 — P-loop containing nucleoside triphosphate hydrolases
Superfamily Superfamily superfamily	c.37.1 — P-loop containing nucleoside triphosphate hydrolases
Family Family family	c.37.1.24 — Type II thymidine kinase

Domain ID domain_id	d1xbtc2
Class class	g — Small proteins
Fold Fold fold	g.39 — Glucocorticoid receptor-like (DNA-binding domain)
Superfamily Superfamily superfamily	g.39.1 — Glucocorticoid receptor-like (DNA-binding domain)
Family Family family	g.39.1.14 — Type II thymidine kinase zinc finger

Domain ID domain_id	d1xbtd1
Class class	c — Alpha and beta proteins (a/b)
Fold Fold fold	c.37 — P-loop containing nucleoside triphosphate hydrolases
Superfamily Superfamily superfamily	c.37.1 — P-loop containing nucleoside triphosphate hydrolases
Family Family family	c.37.1.24 — Type II thymidine kinase

Domain ID domain_id	d1xbtd2
Class class	g — Small proteins
Fold Fold fold	g.39 — Glucocorticoid receptor-like (DNA-binding domain)
Superfamily Superfamily superfamily	g.39.1 — Glucocorticoid receptor-like (DNA-binding domain)
Family Family family	g.39.1.14 — Type II thymidine kinase zinc finger

Domain ID domain_id	d1xbte1
Class class	c — Alpha and beta proteins (a/b)
Fold Fold fold	c.37 — P-loop containing nucleoside triphosphate hydrolases
Superfamily Superfamily superfamily	c.37.1 — P-loop containing nucleoside triphosphate hydrolases
Family Family family	c.37.1.24 — Type II thymidine kinase

Domain ID domain_id	d1xbte2
Class class	g — Small proteins
Fold Fold fold	g.39 — Glucocorticoid receptor-like (DNA-binding domain)
Superfamily Superfamily superfamily	g.39.1 — Glucocorticoid receptor-like (DNA-binding domain)
Family Family family	g.39.1.14 — Type II thymidine kinase zinc finger

Domain ID domain_id	d1xbtf1
Class class	c — Alpha and beta proteins (a/b)
Fold Fold fold	c.37 — P-loop containing nucleoside triphosphate hydrolases
Superfamily Superfamily superfamily	c.37.1 — P-loop containing nucleoside triphosphate hydrolases
Family Family family	c.37.1.24 — Type II thymidine kinase

Domain ID domain_id	d1xbtf2
Class class	g — Small proteins
Fold Fold fold	g.39 — Glucocorticoid receptor-like (DNA-binding domain)
Superfamily Superfamily superfamily	g.39.1 — Glucocorticoid receptor-like (DNA-binding domain)
Family Family family	g.39.1.14 — Type II thymidine kinase zinc finger

Domain ID domain_id	d1xbtg1
Class class	c — Alpha and beta proteins (a/b)
Fold Fold fold	c.37 — P-loop containing nucleoside triphosphate hydrolases
Superfamily Superfamily superfamily	c.37.1 — P-loop containing nucleoside triphosphate hydrolases
Family Family family	c.37.1.24 — Type II thymidine kinase

Domain ID domain_id	d1xbtg2
Class class	g — Small proteins
Fold Fold fold	g.39 — Glucocorticoid receptor-like (DNA-binding domain)
Superfamily Superfamily superfamily	g.39.1 — Glucocorticoid receptor-like (DNA-binding domain)
Family Family family	g.39.1.14 — Type II thymidine kinase zinc finger

Domain ID domain_id	d1xbth1
Class class	c — Alpha and beta proteins (a/b)
Fold Fold fold	c.37 — P-loop containing nucleoside triphosphate hydrolases
Superfamily Superfamily superfamily	c.37.1 — P-loop containing nucleoside triphosphate hydrolases
Family Family family	c.37.1.24 — Type II thymidine kinase

Domain ID domain_id	d1xbth2
Class class	g — Small proteins
Fold Fold fold	g.39 — Glucocorticoid receptor-like (DNA-binding domain)
Superfamily Superfamily superfamily	g.39.1 — Glucocorticoid receptor-like (DNA-binding domain)
Family Family family	g.39.1.14 — Type II thymidine kinase zinc finger

CATH v4.4 (16 domains)

Domain ID domain_id	1xbtA01
Class class	3 — Alpha Beta
Architecture architecture	40 — 3-Layer(aba) Sandwich
Topology topology	50 — Rossmann fold
Homologous superfamily homologous superfamily	300 — P-loop containing nucleotide triphosphate hydrolases

Domain ID domain_id	1xbtA02
Class class	3 — Alpha Beta
Architecture architecture	30 — 2-Layer Sandwich
Topology topology	60 — Wheat Germ Agglutinin (Isolectin 2); domain 1
Homologous superfamily homologous superfamily	20 —

Domain ID domain_id	1xbtB01
Class class	3 — Alpha Beta
Architecture architecture	40 — 3-Layer(aba) Sandwich
Topology topology	50 — Rossmann fold
Homologous superfamily homologous superfamily	300 — P-loop containing nucleotide triphosphate hydrolases

Domain ID domain_id	1xbtB02
Class class	3 — Alpha Beta
Architecture architecture	30 — 2-Layer Sandwich
Topology topology	60 — Wheat Germ Agglutinin (Isolectin 2); domain 1
Homologous superfamily homologous superfamily	20 —

Domain ID domain_id	1xbtC01
Class class	3 — Alpha Beta
Architecture architecture	40 — 3-Layer(aba) Sandwich
Topology topology	50 — Rossmann fold
Homologous superfamily homologous superfamily	300 — P-loop containing nucleotide triphosphate hydrolases

Domain ID domain_id	1xbtC02
Class class	3 — Alpha Beta
Architecture architecture	30 — 2-Layer Sandwich
Topology topology	60 — Wheat Germ Agglutinin (Isolectin 2); domain 1
Homologous superfamily homologous superfamily	20 —

Domain ID domain_id	1xbtD01
Class class	3 — Alpha Beta
Architecture architecture	40 — 3-Layer(aba) Sandwich
Topology topology	50 — Rossmann fold
Homologous superfamily homologous superfamily	300 — P-loop containing nucleotide triphosphate hydrolases

Domain ID domain_id	1xbtD02
Class class	3 — Alpha Beta
Architecture architecture	30 — 2-Layer Sandwich
Topology topology	60 — Wheat Germ Agglutinin (Isolectin 2); domain 1
Homologous superfamily homologous superfamily	20 —

Domain ID domain_id	1xbtE01
Class class	3 — Alpha Beta
Architecture architecture	40 — 3-Layer(aba) Sandwich
Topology topology	50 — Rossmann fold
Homologous superfamily homologous superfamily	300 — P-loop containing nucleotide triphosphate hydrolases

Domain ID domain_id	1xbtE02
Class class	3 — Alpha Beta
Architecture architecture	30 — 2-Layer Sandwich
Topology topology	60 — Wheat Germ Agglutinin (Isolectin 2); domain 1
Homologous superfamily homologous superfamily	20 —

Domain ID domain_id	1xbtF01
Class class	3 — Alpha Beta
Architecture architecture	40 — 3-Layer(aba) Sandwich
Topology topology	50 — Rossmann fold
Homologous superfamily homologous superfamily	300 — P-loop containing nucleotide triphosphate hydrolases

Domain ID domain_id	1xbtF02
Class class	3 — Alpha Beta
Architecture architecture	30 — 2-Layer Sandwich
Topology topology	60 — Wheat Germ Agglutinin (Isolectin 2); domain 1
Homologous superfamily homologous superfamily	20 —

Domain ID domain_id	1xbtG01
Class class	3 — Alpha Beta
Architecture architecture	40 — 3-Layer(aba) Sandwich
Topology topology	50 — Rossmann fold
Homologous superfamily homologous superfamily	300 — P-loop containing nucleotide triphosphate hydrolases

Domain ID domain_id	1xbtG02
Class class	3 — Alpha Beta
Architecture architecture	30 — 2-Layer Sandwich
Topology topology	60 — Wheat Germ Agglutinin (Isolectin 2); domain 1
Homologous superfamily homologous superfamily	20 —

Domain ID domain_id	1xbtH01
Class class	3 — Alpha Beta
Architecture architecture	40 — 3-Layer(aba) Sandwich
Topology topology	50 — Rossmann fold
Homologous superfamily homologous superfamily	300 — P-loop containing nucleotide triphosphate hydrolases

Domain ID domain_id	1xbtH02
Class class	3 — Alpha Beta
Architecture architecture	30 — 2-Layer Sandwich
Topology topology	60 — Wheat Germ Agglutinin (Isolectin 2); domain 1
Homologous superfamily homologous superfamily	20 —

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Unit-cell length a length_a	157.672 Å
Unit-cell length b length_b	123.177 Å
Unit-cell length c length_c	116.000 Å
Unit-cell angle α angle_alpha	90.00 °
Unit-cell angle β angle_beta	130.20 °
Unit-cell angle γ angle_gamma	90.00 °
Molecules per unit cell Z z_pdb	32

Space group space_group	C 1 2 1
Space-group number int_tables_number	5
Crystal system crystal_system	—

Resolution resolution	2.400 Å
Low-resolution limit resolution_low	42.070 Å
R factor r_factor	0.2029
R_work r_work	0.2013
R_free r_free	0.2320

Crystal Structure of Human Thymidine Kinase 1

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

Thymidine kinase, cytosolic

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

1xbt__assembly_1__model_1

1xbt__assembly_1__model_1 | I(q)

1xbt__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

Source Source

Entity 2 Entity 2 non-polymer

Entity 3 Entity 3 non-polymer

Entity 4 Entity 4 non-polymer

Entity 5 Entity 5 water

6. Fold Classification (SCOP + CATH) 32 domains

SCOP 2.08 (16 domains)

CATH v4.4 (16 domains)

7. Citations (1)

Crystal Structure of Human Thymidine Kinase 1

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

Thymidine kinase, cytosolic

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

1xbt__assembly_1__model_1

1xbt__assembly_1__model_1 | I(q)

1xbt__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

Source Source

Entity 2 Entity 2 non-polymer

Entity 3 Entity 3 non-polymer

Entity 4 Entity 4 non-polymer

Entity 5 Entity 5 water

6. Fold Classification (SCOP + CATH) 32 domains

SCOP 2.08 (16 domains)

CATH v4.4 (16 domains)

7. Citations (1)