1qx7

Crystal structure of apoCaM bound to the gating domain of small conductance Ca2+-activated potassium channel

Method: X-RAY DIFFRACTION

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

Calmodulin

Rattus norvegicus

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein homooligomer	Homooligomer	Protein 2	No other associated polymer	Consistent with protein count
2	Protein homooligomer	Homooligomer	Protein 2	No other associated polymer	Consistent with protein count
3	Protein heterocomplex	Heteromer	Protein 2	Small conductance calcium-activated potassium channel protein 2 × 1 （P70604）	Consistent with protein count
4	Protein homooligomer	Homooligomer	Protein 3	No other associated polymer	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	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–148； UniProt 1–148 Author chain B； PDBConstruct 1–148； UniProt 1–148 Author chain I； PDBConstruct 1–148； UniProt 1–148 Author chain M； PDBConstruct 1–148； UniProt 1–148 Author chain R； PDBConstruct 1–148； UniProt 1–148

Small conductance calcium-activated potassium channel protein 2

Rattus norvegicus

UniProt P70604

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
3	Protein heterocomplex	Heteromer	Protein 2	Calmodulin × 1 （P62161）	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	2
Chains and sequence ranges	Author chain D； PDBConstruct 1–77； UniProt 411–487

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	1qx7
Deposition date deposition_date	2003-09-04
Structure title title	Crystal structure of apoCaM bound to the gating domain of small conductance Ca2+-activated potassium channel
Keywords keywords	;apoCalmodulin, SK channel, small conductance Ca2+ activated K+ channel, CaMBD, gating domain, Ca2+-activated gating, functioanl bipartism, 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.

1qx7__assembly_3__model_1

Assembly 3 · Model 1 · CRYSOL 4.1.3-1-20251215 (887e7ef)

Download this curve (.dat)

1qx7__assembly_3__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

1qx7__assembly_3__model_1 | P(r) · Pending

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

Rg（Guinier）	22.55 Å
Rg (electron density)	21.93 Å
Total Rg	22.42 Å
Atom count	1002
Residues	119
Excluded volume	17706 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`1qx7__assembly_1__model_1`	dimeric （2）	Success	4.1.3-1-20251215 (887e7ef)	View Download
2	1	`1qx7__assembly_2__model_1`	dimeric （2）	Success	4.1.3-1-20251215 (887e7ef)	View Download
3	1	`1qx7__assembly_3__model_1`	dimeric （2）	Success	4.1.3-1-20251215 (887e7ef)	View Download
4	1	`1qx7__assembly_4__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 (2)

Entity 1 Entity 1 polymer

Description description	Calmodulin
Molecular weight formula_weight	17143.4 kDa
Source method src_method	man
Copy count entity_count	5

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	I,R,A,B,M
Atom count atom_count	5523

ADQLTEEQIAEFKEAFSLFDKDGDGTITTKELGTVMRSLGQNPTEAELQDMINEVDADGNGTIDFPEFLTMMARKMKDTDSEEEIREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDEEVDEMIREADIDGDGQVNYEEFVQMMTAK

Source Source

Source organism organism	Rattus norvegicus
Common name common_name	Norway rat
NCBI taxonomy ID ncbi_taxonomy_id	10116
Host organism host_organism	Escherichia coli BL21(DE3)

Entity 2 Entity 2 polymer

Description description	Small conductance calcium-activated potassium channel protein 2
Molecular weight formula_weight	10217.0 kDa
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	D

MMDTQLTKRVKNAAANVLRETWLIYKNTKLVKKIDHAKVRKHQRKFLQAIHQLRSVKMEQRKLNDQANTLVDLAKTQLEHHHHHH

Source Source

Source organism organism	Rattus norvegicus
Common name common_name	Norway rat
NCBI taxonomy ID ncbi_taxonomy_id	10116
Host organism host_organism	Escherichia coli BL21(DE3)

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6. Fold Classification (SCOP + CATH) 13 domains

SCOP 2.08 (5 domains)

Domain ID domain_id	d1qx7a_
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

Domain ID domain_id	d1qx7b_
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

Domain ID domain_id	d1qx7i_
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

Domain ID domain_id	d1qx7m_
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

Domain ID domain_id	d1qx7r_
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 (8 domains)

Domain ID domain_id	1qx7A01
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	238 — Recoverin; domain 1
Homologous superfamily homologous superfamily	10 — EF-hand

Domain ID domain_id	1qx7A02
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	238 — Recoverin; domain 1
Homologous superfamily homologous superfamily	10 — EF-hand

Domain ID domain_id	1qx7B00
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	238 — Recoverin; domain 1
Homologous superfamily homologous superfamily	10 — EF-hand

Domain ID domain_id	1qx7I01
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	238 — Recoverin; domain 1
Homologous superfamily homologous superfamily	10 — EF-hand

Domain ID domain_id	1qx7I02
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	238 — Recoverin; domain 1
Homologous superfamily homologous superfamily	10 — EF-hand

Domain ID domain_id	1qx7M01
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	238 — Recoverin; domain 1
Homologous superfamily homologous superfamily	10 — EF-hand

Domain ID domain_id	1qx7R01
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	238 — Recoverin; domain 1
Homologous superfamily homologous superfamily	10 — EF-hand

Domain ID domain_id	1qx7R02
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	238 — Recoverin; domain 1
Homologous superfamily homologous superfamily	10 — EF-hand

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Unit-cell length a length_a	79.930 Å
Unit-cell length b length_b	79.930 Å
Unit-cell length c length_c	220.800 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	40

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

Resolution resolution	3.090 Å
Low-resolution limit resolution_low	75.160 Å
R factor r_factor	0.2860
R_work r_work	0.2860
R_free r_free	0.3080

Crystal structure of apoCaM bound to the gating domain of small conductance Ca2+-activated potassium channel

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

Calmodulin

State in the Current Structure

Other States of the Same Protein in the Database

Small conductance calcium-activated potassium channel protein 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

1qx7__assembly_3__model_1

1qx7__assembly_3__model_1 | I(q)

1qx7__assembly_3__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) 13 domains

SCOP 2.08 (5 domains)

CATH v4.4 (8 domains)

7. Citations (1)

Crystal structure of apoCaM bound to the gating domain of small conductance Ca2+-activated potassium channel

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

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

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

2. Structure Basics 2. Structure Basics

3. Official assembly/model SAXS Official SAXS Profiles

1qx7__assembly_3__model_1

1qx7__assembly_3__model_1 | I(q)

1qx7__assembly_3__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) 13 domains

SCOP 2.08 (5 domains)

CATH v4.4 (8 domains)

7. Citations (1)