9zrq

Cryo-EM structure of KCa2.2/calmodulin channel in complex with SKA31.

Method: ELECTRON MICROSCOPY Dmax: 133.0 Å Quality: GOOD

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

Small conductance calcium-activated potassium channel protein 2

Homo sapiens

UniProt Q9H2S1

State in the Current Structure

Assembly Oligomeric State Construct Mutations and Modifications Ligands, Ions and Associated Components Method and Experimental Conditions Structure Quality
1 Protein heterocomplex Heteromer Protein × 8 PDB declaration: octameric(8) Consistent with protein copy count Chain A; UniProt 117–477 Chain B; UniProt 117–477 Chain C; UniProt 117–477 Chain D; UniProt 117–477 Not recorded Calmodulin-1 × 4 (P0DP23) K POTASSIUM ION × 4 A1C3Q naphtho[1,2-d][1,3]thiazol-2-amine × 4 CA CALCIUM ION × 8 ELECTRON MICROSCOPY cryo-EM buffer:pH 8 cryo-EM vitrification conditions:Cryogen ETHANE Resolution 2.77 Å

Other States of the Same Protein in the Database

Each row is a biological assembly of the same UniProt protein in another PDB entry. The “Difference from current entry” column identifies evidence-level differences; no tag means the currently parsed fields agree.

15 other PDB entries and 17 assemblies. Open the comparison page and filter oligomeric states

View Construct and Data Evidence
UniProt name KCNN2_HUMAN
Isoform
PDB entities 1
Chains and sequence ranges Author chain A; PDBConstruct 1–361; UniProt 117–477 Author chain B; PDBConstruct 1–361; UniProt 117–477 Author chain C; PDBConstruct 1–361; UniProt 117–477 Author chain D; PDBConstruct 1–361; UniProt 117–477

Calmodulin-1

Homo sapiens

UniProt P0DP23

State in the Current Structure

Assembly Oligomeric State Construct Mutations and Modifications Ligands, Ions and Associated Components Method and Experimental Conditions Structure Quality
1 Protein heterocomplex Heteromer Protein × 8 PDB declaration: octameric(8) Consistent with protein copy count Chain E; UniProt 3–148 Chain F; UniProt 3–148 Chain G; UniProt 3–148 Chain H; UniProt 3–148 Not recorded Small conductance calcium-activated potassium channel protein 2 × 4 (Q9H2S1) K POTASSIUM ION × 4 A1C3Q naphtho[1,2-d][1,3]thiazol-2-amine × 4 CA CALCIUM ION × 8 ELECTRON MICROSCOPY cryo-EM buffer:pH 8 cryo-EM vitrification conditions:Cryogen ETHANE Resolution 2.77 Å

Other States of the Same Protein in the Database

Each row is a biological assembly of the same UniProt protein in another PDB entry. The “Difference from current entry” column identifies evidence-level differences; no tag means the currently parsed fields agree.

213 other PDB entries and 279 assemblies. Open the comparison page and filter oligomeric states

View Construct and Data Evidence
UniProt name CALM1_HUMAN
Isoform
PDB entities 2
Chains and sequence ranges Author chain E; PDBConstruct 1–146; UniProt 3–148 Author chain F; PDBConstruct 1–146; UniProt 3–148 Author chain G; PDBConstruct 1–146; UniProt 3–148 Author chain H; PDBConstruct 1–146; UniProt 3–148

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.

SAXS scattering curve SAXS Profile

SAXS profile for 9zrq

P(r) Distance Distribution P(r) Distribution

P(r) distribution for 9zrq
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2. Structure Basics 2. Structure Basics

Entry ID entry_id9zrq
Deposition date deposition_date2025-12-20
Structure title titleCryo-EM structure of KCa2.2/calmodulin channel in complex with SKA31.
Keywords keywords;Intermediate conductance calcium-activated potassium channel, Ion channel, Calmodulin binding protein, TRANSPORT PROTEIN, MEMBRANE PROTEIN ;; MEMBRANE PROTEIN
Experimental Method methodELECTRON MICROSCOPY

3. SAXS Parameters (CRYSOL theoretical calculation) 3. SAXS Parameters (CRYSOL)

Radius of gyration Rg (Guinier) rg_guinier44.34
Radius of gyration Rg (electron density) rg_electron43.62
Forward intensity I(0) i01465840000.00
Molecular weight molecular_weight211470.0 kDa
Excluded volume excluded_volume205280 ų
Envelope volume envelope_volume438460 ų
Hydration-shell volume shell_volume81610 ų
Envelope diameter envelope_diameter142.6
Shell Rg shell_rg51.42
Envelope Rg envelope_rg41.88
Shape Rg shape_rg43.65
Total Rg total_rg43.84
Total atoms total_atoms15961
Residues n_residues2028
Spherical-harmonic order n_harmonics20
q range q_range— – 0.5000 −1
Data points n_points101
Shell type shell_typedirectional
Solvent electron density solvent_density0.3340 e/ų
Shell contrast contrast_shell0.0300 e/ų
CRYSOL version crysol_version4.1.3

4. P(r) Distance Distribution (GNOM inversion) 4. P(r) Analysis (GNOM)

Maximum dimension Dmax dmax133.0
Rg (real space) rg_real43.97
Rg uncertainty (real space) rg_real_error0.78
I(0) (real space) i0_real1.4660e+09
I(0) uncertainty (real space) i0_real_error2.3890e+07
Rg (reciprocal space) rg_reciprocal44.34
I(0) (reciprocal space) i0_reciprocal1466000000.0000
Solution quality estimate total_estimate0.8946
Solution quality rating solution_quality GOOD a GOOD solution
P(r) peaks n_peaks2
Primary peak position r_peak_primary62.8
Skewness Skewness skewness-0.050
Kurtosis Kurtosis kurtosis-0.547
Angular range angular_range— – 0.1800 −1
Current regularization parameter α current_alpha0.0000
Highest regularization parameter α highest_alpha78600000.0000
Real-space data points n_real_points37
GNOM version gnom_version4.1.3
Quality Criteria quality_criteria AN1: 0.000; Oscil: 0.913; Stabil: 1.000; Sysdev: 1.000; Positv: 1.000; Valcen: 0.953; Smooth: 0.933

5. Crystallography and Experiment 5. Crystallography & Experiment

6. Entities and Polymers Entities & Polymers (6)

8. Citations (1)

9. Files and Curves (10)