9VUA: Channel A complex with 1
channel A complex with 1. Determined by electron microscopy at 3.23 Å resolution. Released 11 Mar 2026.
- Method
- Electron microscopy
- Resolution
- 3.23 Å
- Organisms
- Homo sapiens, Apis mellifera
- Chains
- 8
- Atoms
- 12,285
- Mol. weight
- 311.16 kDa
- Ligands
- POV
- Released
- 11 Mar 2026
Explore 9VUA in 3D
Show helices and sheets
RCSB PDB
PDBe
Secondary structure: helices and β-sheets
9VUA contains 78 α-helices and 8 β-strands across 8 chains. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.
Chain A: 17 helices, 2 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 119-156 | 38 | |
| α-helix | 165-199 | 35 | |
| α-helix | 205-208 | 4 | |
| α-helix | 211-223 | 13 | |
| β-strand | 234-240 | 7 | 1 |
| β-strand | 247-253 | 7 | 1 |
| α-helix | 254-259 | 6 | |
| α-helix | 260-266 | 7 | |
| α-helix | 267-276 | 10 | |
| α-helix | 278-281 | 4 | |
| α-helix | 298-308 | 11 | |
| α-helix | 310-333 | 24 | |
| α-helix | 334-336 | 3 | |
| α-helix | 345-356 | 12 | |
| α-helix | 369-396 | 28 | |
| α-helix | 398-400 | 3 | |
| α-helix | 401-434 | 34 | |
| α-helix | 435-439 | 5 | |
| α-helix | 445-472 | 28 | |
Chain B: 17 helices, 2 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 119-156 | 38 | |
| α-helix | 165-199 | 35 | |
| α-helix | 205-208 | 4 | |
| α-helix | 211-223 | 13 | |
| α-helix | 228-229 | 2 | |
| β-strand | 234-240 | 7 | 2 |
| β-strand | 247-253 | 7 | 2 |
| α-helix | 254-259 | 6 | |
| α-helix | 260-266 | 7 | |
| α-helix | 267-276 | 10 | |
| α-helix | 283-292 | 10 | |
| α-helix | 298-308 | 11 | |
| α-helix | 310-333 | 24 | |
| α-helix | 334-336 | 3 | |
| α-helix | 345-356 | 12 | |
| α-helix | 369-396 | 28 | |
| α-helix | 401-434 | 34 | |
| α-helix | 435-439 | 5 | |
| α-helix | 445-472 | 28 | |
Chain C: 17 helices, 2 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 119-155 | 37 | |
| α-helix | 165-199 | 35 | |
| α-helix | 205-208 | 4 | |
| α-helix | 211-223 | 13 | |
| β-strand | 234-240 | 7 | 3 |
| β-strand | 247-253 | 7 | 3 |
| α-helix | 255-259 | 5 | |
| α-helix | 260-266 | 7 | |
| α-helix | 267-275 | 9 | |
| α-helix | 278-281 | 4 | |
| α-helix | 283-291 | 9 | |
| α-helix | 298-308 | 11 | |
| α-helix | 310-333 | 24 | |
| α-helix | 345-356 | 12 | |
| α-helix | 369-396 | 28 | |
| α-helix | 398-400 | 3 | |
| α-helix | 401-434 | 34 | |
| α-helix | 435-439 | 5 | |
| α-helix | 445-472 | 28 | |
Chain D: 13 helices, 2 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 120-156 | 37 | |
| α-helix | 165-199 | 35 | |
| α-helix | 205-207 | 3 | |
| α-helix | 211-223 | 13 | |
| β-strand | 234-240 | 7 | 4 |
| β-strand | 247-253 | 7 | 4 |
| α-helix | 254-259 | 6 | |
| α-helix | 260-266 | 7 | |
| α-helix | 267-276 | 10 | |
| α-helix | 278-281 | 4 | |
| α-helix | 283-291 | 9 | |
| α-helix | 298-308 | 11 | |
| α-helix | 310-333 | 24 | |
| α-helix | 345-356 | 12 | |
| α-helix | 369-396 | 28 | |
Chain E: 4 helices, 0 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 83-87 | 5 | |
| α-helix | 102-109 | 8 | |
| α-helix | 118-128 | 11 | |
| α-helix | 138-145 | 8 | |
Chain F: 5 helices, 0 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 83-90 | 8 | |
| α-helix | 102-106 | 5 | |
| α-helix | 107-111 | 5 | |
| α-helix | 118-128 | 11 | |
| α-helix | 138-145 | 8 | |
Chain G: 4 helices, 0 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 83-87 | 5 | |
| α-helix | 102-108 | 7 | |
| α-helix | 118-128 | 11 | |
| α-helix | 138-144 | 7 | |
Chain H: 1 helix, 0 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 9-15 | 7 | |
Molecules and chains
| Molecule | Chains | Type | Length | Organism | UniProt |
|---|
| Calmodulin-1 | E, F, G | protein | 149 | Homo sapiens | P0DP23 (AlphaFold model) |
| Small conductance calcium-activated potassium channel protein 2 | A, B, C, D | protein | 579 | Homo sapiens | Q9H2S1 (AlphaFold model) |
| Apamin | H | protein | 18 | Apis mellifera | P01500 (AlphaFold model) |
Sequence of entity 1 (E, F, G), FASTA
>9VUA_1 Calmodulin-1 (chains E, F, G)
MADQLTEEQIAEFKEAFSLFDKDGDGTITTKELGTVMRSLGQNPTEAELQDMINEVDADG
NGTIDFPEFLTMMARKMKDTDSEEEIREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDE
EVDEMIREADIDGDGQVNYEEFVQMMTAK
Sequence of entity 2 (A, B, C, D), FASTA
>9VUA_2 Small conductance calcium-activated potassium channel protein 2 (chains A, B, C, D)
MSSCRYNGGVMRPLSNLSASRRNLHEMDSEAQPLQPPASVGGGGGASSPSAAAAAAAAVS
SSAPEIVVSKPEHNNSNNLALYGTGGGGSTGGGGGGGGSGHGSSSGTKSSKKKNQNIGYK
LGHRRALFEKRKRLSDYALIFGMFGIVVMVIETELSWGAYDKASLYSLALKCLISLSTII
LLGLIIVYHAREIQLFMVDNGADDWRIAMTYERIFFICLEILVCAIHPIPGNYTFTWTAR
LAFSYAPSTTTADVDIILSIPMFLRLYLIARVMLLHSKLFTDASSRSIGALNKINFNTRF
VMKTLMTICPGTVLLVFSISLWIIAAWTVRACERYHDQQDVTSNFLGAMWLISITFLSIG
YGDMVPNTYCGKGVCLLTGIMGAGCTALVVAVVARKLELTKAEKHVHNFMMDTQLTKRVK
NAAANVLRETWLIYKNTKLVKKIDHAKVRKHQRKFLQAIHQLRSVKMEQRKLNDQANTLV
DLAKTQNIMYDMISDLNERSEDFEKRIVTLETKLETLIGSIHALPGLISQTIRQQQRDFI
EAQMESYDKHVTYNAERSRSSSRRRRSSSTAPPTSSESS
Sequence of entity 3 (H), FASTA
>9VUA_3 Apamin (chains H)
CNCKAPETALCARRCQQH
Ligands and cofactors
| ID | Name | Formula | Copies |
|---|
| POV | (2S)-3-(hexadecanoyloxy)-2-[(9Z)-octadec-9-enoyloxy]propyl… | C42 H82 N O8 P | 4 |
Water and common crystallization additives (K) are not listed.
Primary citation
Structural mechanisms for inhibition and activation of human small-conductance Ca 2+ -activated potassium channel SK2. Ma, B., Wu, D., Cao, E. et al. Nat Commun (2026) 17:1770-1770. DOI 10.1038/s41467-026-68475-4 · PubMed
Other PDB entries of the same protein (UniProt P0DP23 (AlphaFold model), which also has an AlphaFold model), best resolution first:
- 9MXD 1.17 Å, Human E104A calmodulin:MLCK RM20 complex
- 7BF1 1.24 Å, Ca2+-Calmodulin in complex with peptide from brain-type creatine kinase in extended 1:2…
- 6XXX 1.25 Å, 1.25 Angstrom crystal structure of Ca/CaM A102V:RyR2 peptide complex
- 4DJC 1.35 Å, 1.35 A crystal structure of the NaV1.5 DIII-IV-Ca/CaM complex
- 7BF2 1.43 Å, Ca2+-Calmodulin in complex with human muscle form creatine kinase peptide in extended…
- 2F3Y 1.45 Å, Calmodulin/IQ domain complex
- 2W73 1.45 Å, High-resolution structure of the complex between calmodulin and a peptide from…
- 4LZX 1.5 Å, Complex of IQCG and Ca2+-free CaM
- 5V03 1.58 Å, A positive allosteric modulator binding pocket in SK2 ion channels is shared by Riluzole…
- 9MVW 1.58 Å, Crystal structure of S101F calmodulin - CaM:RM20 analog complex
- 2F3Z 1.6 Å, Calmodulin/IQ-AA domain complex
- 6M7H 1.6 Å, Structure of calmodulin with KN93
Browse structure collections
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