2b26

The crystal structure of the protein complex of yeast Hsp40 Sis1 and Hsp70 Ssa1

Method: X-RAY DIFFRACTION

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

SIS1 protein

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	Heat shock 70 kDa protein cognate 2 × 1 （P11146）	Consistent with protein count
2	Protein homooligomer	Homooligomer	Protein 2	No other associated polymer	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	SIS1_YEAST
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 2–173； UniProt 181–352 Author chain B； PDBConstruct 2–173； UniProt 181–352 Author chain C； PDBConstruct 2–173； UniProt 181–352

Heat shock 70 kDa protein cognate 2

Drosophila melanogaster

UniProt P11146

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 3	SIS1 protein × 2 （P25294）	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	HSP7B_DROME
Isoform	—
PDB entities	2
Chains and sequence ranges	Author chain D； PDBConstruct 1–7； UniProt 626–632

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	2b26
Deposition date deposition_date	2005-09-16
Structure title title	The crystal structure of the protein complex of yeast Hsp40 Sis1 and Hsp70 Ssa1
Keywords keywords	Hsp40 Sis1 Hsp70 Ssa1, CHAPERONE-PROTEIN TRANSPORT COMPLEX; CHAPERONE/PROTEIN TRANSPORT
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.

2b26__assembly_1__model_1

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

Download this curve (.dat)

2b26__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

2b26__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	28.23 Å
Rg (electron density)	27.28 Å
Total Rg	28.18 Å
Atom count	2463
Residues	311
Excluded volume	44329 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`2b26__assembly_1__model_1`	trimeric （3）	Success	4.1.3-1-20251215 (887e7ef)	View Download
2	1	`2b26__assembly_2__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 (2)

Entity 1 Entity 1 polymer

Description description	SIS1 protein
Molecular weight formula_weight	19488.2 kDa
Source method src_method	man
Copy count entity_count	3

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,B,C
Atom count atom_count	3428

ETVQVNLPVSLEDLFVGKKKSFKIGRKGPHGASEKTQIDIQLKPGWKAGTKITYKNQGDYNPQTGRRKTLQFVIQEKSHPNFKRDGDDLIYTLPLSFKESLLGFSKTIQTIDGRTLPLSRVQPVQPSQTSTYPGQGMPTPKNPSQRGNLIVKYKVDYPISLNDAQKRAIDENF

Source Source

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

Entity 2 Entity 2 polymer

Description description	Heat shock 70 kDa protein cognate 2
Molecular weight formula_weight	787.8 kDa
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	D

PTVEEVD

Source Source

Source organism organism	Drosophila melanogaster
Common name common_name	fruit fly
NCBI taxonomy ID ncbi_taxonomy_id	7227
Host organism host_organism	Escherichia coli

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6. Fold Classification (SCOP + CATH) 12 domains

SCOP 2.08 (6 domains)

Domain ID domain_id	d2b26a1
Class class	b — All beta proteins
Fold Fold fold	b.4 — HSP40/DnaJ peptide-binding domain
Superfamily Superfamily superfamily	b.4.1 — HSP40/DnaJ peptide-binding domain
Family Family family	b.4.1.1 — HSP40/DnaJ peptide-binding domain

Domain ID domain_id	d2b26a2
Class class	b — All beta proteins
Fold Fold fold	b.4 — HSP40/DnaJ peptide-binding domain
Superfamily Superfamily superfamily	b.4.1 — HSP40/DnaJ peptide-binding domain
Family Family family	b.4.1.1 — HSP40/DnaJ peptide-binding domain

Domain ID domain_id	d2b26a3
Class class	l — Artifacts
Fold Fold fold	l.1 — Tags
Superfamily Superfamily superfamily	l.1.1 — Tags
Family Family family	l.1.1.1 — Tags

Domain ID domain_id	d2b26b1
Class class	b — All beta proteins
Fold Fold fold	b.4 — HSP40/DnaJ peptide-binding domain
Superfamily Superfamily superfamily	b.4.1 — HSP40/DnaJ peptide-binding domain
Family Family family	b.4.1.1 — HSP40/DnaJ peptide-binding domain

Domain ID domain_id	d2b26b2
Class class	b — All beta proteins
Fold Fold fold	b.4 — HSP40/DnaJ peptide-binding domain
Superfamily Superfamily superfamily	b.4.1 — HSP40/DnaJ peptide-binding domain
Family Family family	b.4.1.1 — HSP40/DnaJ peptide-binding domain

Domain ID domain_id	d2b26b3
Class class	l — Artifacts
Fold Fold fold	l.1 — Tags
Superfamily Superfamily superfamily	l.1.1 — Tags
Family Family family	l.1.1.1 — Tags

CATH v4.4 (6 domains)

Domain ID domain_id	2b26A01
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	260 — HSP40/DNAj peptide-binding domain
Homologous superfamily homologous superfamily	20 — Urease metallochaperone UreE, N-terminal domain

Domain ID domain_id	2b26A02
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	260 — HSP40/DNAj peptide-binding domain
Homologous superfamily homologous superfamily	20 — Urease metallochaperone UreE, N-terminal domain

Domain ID domain_id	2b26B01
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	260 — HSP40/DNAj peptide-binding domain
Homologous superfamily homologous superfamily	20 — Urease metallochaperone UreE, N-terminal domain

Domain ID domain_id	2b26B02
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	260 — HSP40/DNAj peptide-binding domain
Homologous superfamily homologous superfamily	20 — Urease metallochaperone UreE, N-terminal domain

Domain ID domain_id	2b26C01
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	260 — HSP40/DNAj peptide-binding domain
Homologous superfamily homologous superfamily	20 — Urease metallochaperone UreE, N-terminal domain

Domain ID domain_id	2b26C02
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	260 — HSP40/DNAj peptide-binding domain
Homologous superfamily homologous superfamily	20 — Urease metallochaperone UreE, N-terminal domain

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Unit-cell length a length_a	113.867 Å
Unit-cell length b length_b	113.867 Å
Unit-cell length c length_c	173.881 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	24

Space group space_group	P 41 21 2
Space-group number int_tables_number	92
Crystal system crystal_system	—

Resolution resolution	3.200 Å
Low-resolution limit resolution_low	30.000 Å
R factor r_factor	0.2760
R_work r_work	0.2760
R_free r_free	0.3390

The crystal structure of the protein complex of yeast Hsp40 Sis1 and Hsp70 Ssa1

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

SIS1 protein

State in the Current Structure

Other States of the Same Protein in the Database

Heat shock 70 kDa protein cognate 2

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

2b26__assembly_1__model_1

2b26__assembly_1__model_1 | I(q)

2b26__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 (2)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

6. Fold Classification (SCOP + CATH) 12 domains

SCOP 2.08 (6 domains)

CATH v4.4 (6 domains)

7. Citations (1)

The crystal structure of the protein complex of yeast Hsp40 Sis1 and Hsp70 Ssa1

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

SIS1 protein

State in the Current Structure

Other States of the Same Protein in the Database

Monomer

Homodimer

Homotetramer

Other homooligomers

Heteromeric or nucleic-acid complex

Heat shock 70 kDa protein cognate 2

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

2b26__assembly_1__model_1

2b26__assembly_1__model_1 | I(q)

2b26__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 (2)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

6. Fold Classification (SCOP + CATH) 12 domains

SCOP 2.08 (6 domains)

CATH v4.4 (6 domains)

7. Citations (1)