SAXSdb — 1qb2

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

HUMAN SIGNAL RECOGNITION PARTICLE 54 KD PROTEIN

Homo sapiens

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein homooligomer	Homooligomer	Protein 2	water × 2	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	SRP54_HUMAN
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–109； UniProt 326–434 Author chain B； PDBConstruct 1–109； UniProt 326–434

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	1qb2
Deposition date deposition_date	1999-04-29
Structure title title	CRYSTAL STRUCTURE OF THE CONSERVED SUBDOMAIN OF HUMAN PROTEIN SRP54M AT 2.1A RESOLUTION: EVIDENCE FOR THE MECHANISM OF SIGNAL PEPTIDE BINDING
Keywords keywords	ALPHA-HELIX, HELIX-TURN-HELIX, SIGNALING PROTEIN; SIGNALING PROTEIN
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.

1qb2__assembly_1__model_1

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

Download this curve (.dat)

1qb2__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

1qb2__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	21.68 Å
Rg (electron density)	21.02 Å
Total Rg	21.66 Å
Atom count	1706
Residues	216
Excluded volume	30446 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`1qb2__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 (2)

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6. Fold Classification (SCOP + CATH) 4 domains

SCOP 2.08 (2 domains)

Domain ID domain_id	d1qb2a_
Class class	a — All alpha proteins
Fold Fold fold	a.36 — Signal peptide-binding domain
Superfamily Superfamily superfamily	a.36.1 — Signal peptide-binding domain
Family Family family	a.36.1.1 — Signal peptide-binding domain

Domain ID domain_id	d1qb2b_
Class class	a — All alpha proteins
Fold Fold fold	a.36 — Signal peptide-binding domain
Superfamily Superfamily superfamily	a.36.1 — Signal peptide-binding domain
Family Family family	a.36.1.1 — Signal peptide-binding domain

CATH v4.4 (2 domains)

Domain ID domain_id	1qb2A00
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	260 — 434 Repressor (Amino-terminal Domain)
Homologous superfamily homologous superfamily	30 — Signal recognition particle, SRP54 subunit, M-domain

Domain ID domain_id	1qb2B00
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	260 — 434 Repressor (Amino-terminal Domain)
Homologous superfamily homologous superfamily	30 — Signal recognition particle, SRP54 subunit, M-domain

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Unit-cell length a length_a	28.910 Å
Unit-cell length b length_b	61.340 Å
Unit-cell length c length_c	129.220 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 21 21 21
Space-group number int_tables_number	19
Crystal system crystal_system	—

Resolution resolution	2.100 Å
Low-resolution limit resolution_low	50.000 Å
R factor r_factor	—
R_work r_work	0.2450
R_free r_free	0.3180

Description description	HUMAN SIGNAL RECOGNITION PARTICLE 54 KD PROTEIN
Molecular weight formula_weight	12473.4 kDa
Source method src_method	man
Copy count entity_count	2

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,B
Atom count atom_count	1790

CRYSTAL STRUCTURE OF THE CONSERVED SUBDOMAIN OF HUMAN PROTEIN SRP54M AT 2.1A RESOLUTION: EVIDENCE FOR THE MECHANISM OF SIGNAL PEPTIDE BINDING

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

HUMAN SIGNAL RECOGNITION PARTICLE 54 KD PROTEIN

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

1qb2__assembly_1__model_1

1qb2__assembly_1__model_1 | I(q)

1qb2__assembly_1__model_1 | P(r) · Pending

4. Crystallography and Experiment 4. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

Refinement Refinement

5. Entities and Polymers Entities & Polymers (2)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 water

6. Fold Classification (SCOP + CATH) 4 domains

SCOP 2.08 (2 domains)

CATH v4.4 (2 domains)

7. Citations (1)

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

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	84

CRYSTAL STRUCTURE OF THE CONSERVED SUBDOMAIN OF HUMAN PROTEIN SRP54M AT 2.1A RESOLUTION: EVIDENCE FOR THE MECHANISM OF SIGNAL PEPTIDE BINDING

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

HUMAN SIGNAL RECOGNITION PARTICLE 54 KD 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

2. Structure Basics 2. Structure Basics

3. Official assembly/model SAXS Official SAXS Profiles

1qb2__assembly_1__model_1

1qb2__assembly_1__model_1 | I(q)

1qb2__assembly_1__model_1 | P(r) · Pending

4. Crystallography and Experiment 4. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

Refinement Refinement

5. Entities and Polymers Entities & Polymers (2)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 water

6. Fold Classification (SCOP + CATH) 4 domains

SCOP 2.08 (2 domains)

CATH v4.4 (2 domains)

7. Citations (1)