SAXSdb — 4qnh

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

Small conductance calcium-activated potassium channel protein 2

Rattus norvegicus

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 4	Calmodulin × 2 （P62161） SULFATE ION × 2 CALCIUM ION × 4 water × 4	Consistent with protein count
2	Protein heterocomplex	Heteromer	Protein 2	Calmodulin × 1 （P62161） SULFATE ION × 1 CALCIUM ION × 2 water × 2	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	KCNN2_RAT
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain B； PDBConstruct 3–94； UniProt 396–487

Calmodulin

Rattus norvegicus

UniProt P62161

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 4	Small conductance calcium-activated potassium channel protein 2 × 2 （P70604） SULFATE ION × 2 CALCIUM ION × 4 water × 4	Consistent with protein count
2	Protein heterocomplex	Heteromer	Protein 2	Small conductance calcium-activated potassium channel protein 2 × 1 （P70604） SULFATE ION × 1 CALCIUM ION × 2 water × 2	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	CALM_RAT
Isoform	—
PDB entities	2
Chains and sequence ranges	Author chain R； PDBConstruct 1–149； UniProt 1–149

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	4qnh
Deposition date deposition_date	2014-06-17
Structure title title	Calcium-calmodulin (T79D) complexed with the calmodulin binding domain from a small conductance potassium channel SK2-a
Keywords keywords	ion channel, ion transport-protein binding complex; ion transport/protein binding
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.

4qnh__assembly_1__model_1

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

Download this curve (.dat)

4qnh__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

4qnh__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	27.04 Å
Rg (electron density)	26.27 Å
Total Rg	26.97 Å
Atom count	7418
Residues	466
Excluded volume	66083 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`4qnh__assembly_1__model_1`	tetrameric （4）	Success	4.1.3-1-20251215 (887e7ef)	View Download
2	1	`4qnh__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 (5)

Entity 1 Entity 1 polymer

Description description	Small conductance calcium-activated potassium channel protein 2
Molecular weight formula_weight	12243.4 kDa
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	B
Atom count atom_count	3964

MGRKLELTKAEKHVHNFMMDTQLTKRVKNAAANVLRETWLIYKNTKLVKKIDHAKVRKHQRKFLQAIHQLRSVKMEQRKLNDQANTLVDLAKTQLEHHHHHH

Source Source

Source organism organism	Rattus norvegicus
Common name common_name	rat
NCBI taxonomy ID ncbi_taxonomy_id	10116
Host organism host_organism	Escherichia coli

Entity 2 Entity 2 polymer

Description description	Calmodulin
Molecular weight formula_weight	16866.5 kDa
Mutation mutation	T79D
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	R

MADQLTEEQIAEFKEAFSLFDKDGDGTITTKELGTVMRSLGQNPTEAELQDMINEVDADGNGTIDFPEFLTMMARKMKDDDSEEEIREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDEEVDEMIREADIDGDGQVNYEEFVQMMTAK

Source Source

Source organism organism	Rattus norvegicus
Common name common_name	rat
NCBI taxonomy ID ncbi_taxonomy_id	10116
Host organism host_organism	Escherichia coli

Entity 3 Entity 3 non-polymer

Description description	SULFATE ION
Molecular weight formula_weight	96.1 kDa
Source method src_method	syn
Copy count entity_count	1

Entity 4 Entity 4 non-polymer

Description description	CALCIUM ION
Molecular weight formula_weight	40.1 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	187

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6. Fold Classification (SCOP + CATH) 5 domains

SCOP 2.08 (4 domains)

Domain ID domain_id	d4qnhb1
Class class	f — Membrane and cell surface proteins and peptides
Fold Fold fold	f.15 — Small-conductance potassium channel
Superfamily Superfamily superfamily	f.15.1 — Small-conductance potassium channel
Family Family family	f.15.1.1 — Small-conductance potassium channel

Domain ID domain_id	d4qnhb2
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	d4qnhb3
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	d4qnhr_
Class class	a — All alpha proteins
Fold Fold fold	a.39 — EF Hand-like
Superfamily Superfamily superfamily	a.39.1 — EF-hand
Family Family family	a.39.1.5 — Calmodulin-like

CATH v4.4 (1 domains)

Domain ID domain_id	4qnhB00
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	287 — Helix Hairpins
Homologous superfamily homologous superfamily	70 —

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Unit-cell length a length_a	77.160 Å
Unit-cell length b length_b	65.960 Å
Unit-cell length c length_c	64.680 Å
Unit-cell angle α angle_alpha	90.00 °
Unit-cell angle β angle_beta	93.56 °
Unit-cell angle γ angle_gamma	90.00 °
Molecules per unit cell Z z_pdb	4

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

Resolution resolution	2.020 Å
Low-resolution limit resolution_low	26.648 Å
R factor r_factor	0.1843
R_work r_work	0.1818
R_free r_free	0.2344

Calcium-calmodulin (T79D) complexed with the calmodulin binding domain from a small conductance potassium channel SK2-a

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

Small conductance calcium-activated potassium channel protein 2

State in the Current Structure

Other States of the Same Protein in the Database

Calmodulin

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

4qnh__assembly_1__model_1

4qnh__assembly_1__model_1 | I(q)

4qnh__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 polymer

Polymer Polymer

Source Source

Entity 3 Entity 3 non-polymer

Entity 4 Entity 4 non-polymer

Entity 5 Entity 5 water

6. Fold Classification (SCOP + CATH) 5 domains

SCOP 2.08 (4 domains)

CATH v4.4 (1 domains)

7. Citations (1)

Calcium-calmodulin (T79D) complexed with the calmodulin binding domain from a small conductance potassium channel SK2-a

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

Small conductance calcium-activated potassium channel protein 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

Calmodulin

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

4qnh__assembly_1__model_1

4qnh__assembly_1__model_1 | I(q)

4qnh__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 polymer

Polymer Polymer

Source Source

Entity 3 Entity 3 non-polymer

Entity 4 Entity 4 non-polymer

Entity 5 Entity 5 water

6. Fold Classification (SCOP + CATH) 5 domains

SCOP 2.08 (4 domains)

CATH v4.4 (1 domains)

7. Citations (1)