9UC8: Human KCNQ1-KCNE1-CaM complex with PIP2

structure of human KCNQ1-KCNE1-CaM complex with PIP2. Determined by electron microscopy at 3.36 Å resolution. Released 5 Nov 2025.

Method: Electron microscopy
Resolution: 3.36 Å
Organism: Homo sapiens
Chains: 12
Atoms: 15,595
Mol. weight: 386.32 kDa
Ligands: PIO
Released: 5 Nov 2025

Explore 9UC8 in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9UC8 contains 100 α-helices and 0 β-strands across 12 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.

Chains A, D, G and J: 15 helices, 0 β-strands

Element	Residues	Length
α-helix	105-114	10
α-helix	121-142	22
α-helix	156-174	19
α-helix	186-194	9
α-helix	197-217	21
α-helix	226-238	13
α-helix	248-257	10
α-helix	261-283	23
α-helix	299-310	12
α-helix	326-335	10
α-helix	342-344	3
α-helix	347-351	5
α-helix	356-385	30
α-helix	507-532	26
α-helix	549-575	27

Chains B, E, H and K: 9 helices, 0 β-strands

Element	Residues	Length
α-helix	7-21	15
α-helix	26-35	10
α-helix	36-39	4
α-helix	46-57	12
α-helix	66-74	9
α-helix	80-93	14
α-helix	105-112	8
α-helix	123-131	9
α-helix	139-148	10

Chains C, F, I and L: 1 helix, 0 β-strands

Element	Residues	Length	Sheet
α-helix	43-62	20

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Potassium voltage-gated channel subfamily KQT member 1	A, D, G, J	protein	676	Homo sapiens	P51787 (AlphaFold model)
Calmodulin-1	B, E, H, K	protein	149	Homo sapiens	P0DP23 (AlphaFold model)
Potassium voltage-gated channel subfamily E member 1	C, F, I, L	protein	30	Homo sapiens	P15382 (AlphaFold model)

Sequence of entity 1 (A, D, G, J), FASTA

>9UC8_1 Potassium voltage-gated channel subfamily KQT member 1 (chains A, D, G, J)
MAAASSPPRAERKRWGWGRLPGARRGSAGLAKKCPFSLELAEGGPAGGALYAPIAPGAPG
PAPPASPAAPAAPPVASDLGPRPPVSLDPRVSIYSTRRPVLARTHVQGRVYNFLERPTGW
KCFVYHFAVFLIVLVCLIFSVLSTIEQYAALATGTLFWMEIVLVVFFGTEYVVRLWSAGC
RSKYVGLWGRLRFARKPISIIDLIVVVASMVVLCVGSKGQVFATSAIRGIRFLQILRMLH
VDRQGGTWRLLGSVVFIHRQELITTLYIGFLGLIFSSYFVYLAEKDAVNESGRVEFGSYA
DALWWGVVTVTTIGYGDKVPQTWVGKTIASCFSVFAISFFALPAGILGSGFALKVQQKQR
QKHFNRQIPAAASLIQTAWRCYAAENPDSSTWKIYIRKAPRSHTLLSPSPKPKKSVVVKK
KKFKLDKDNGVTPGEKMLTVPHITCDPPEERRLDHFSVDGYDSSVRKSPTLLEVSMPHFM
RTNSFAEDLDLEGETLLTPITHISQLREHHRATIKVIRRMQYFVAKKKFQQARKPYDVRD
VIEQYSQGHLNLMVRIKELQRRLDQSIGKPSLFISVSEKSKDRGSNTIGARLNRVEDKVT
QLDQRLALITDMLHQLLSLHGGSTPGSGGPPREGGAHITQPCGSGGSVDPELFLPSNTLP
TYEQLTVPRRGPDEGS

Sequence of entity 2 (B, E, H, K), FASTA

>9UC8_2 Calmodulin-1 (chains B, E, H, K)
MADQLTEEQIAEFKEAFSLFDKDGDGTITTKELGTVMRSLGQNPTEAELQDMINEVDADG
NGTIDFPEFLTMMARKMKDTDSEEEIREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDE
EVDEMIREADIDGDGQVNYEEFVQMMTAK

Sequence of entity 3 (C, F, I, L), FASTA

>9UC8_3 Potassium voltage-gated channel subfamily E member 1 (chains C, F, I, L)
DGKLEALYVLMVLGFFGFFTLGIMLSYIRS

Ligands and cofactors

ID	Name	Formula	Copies
PIO	[(2R)-2-octanoyloxy-3-[oxidanyl-[(1R,2R,3S,4R,5R,6S)-2,3,6-tris(oxidanyl)-4,5-d…	C25 H49 O19 P3	8

Water and common crystallization additives (K) are not listed.

Primary citation

Secondary structure transitions and dual PIP2 binding define cardiac KCNQ1-KCNE1 channel gating. Zhong, L., Lin, X., Cheng, X. et al. Cell Res (2025) 35:887-899. DOI 10.1038/s41422-025-01182-9 · PubMed

Other PDB entries of the same protein (UniProt P51787 (AlphaFold model), which also has an AlphaFold model), best resolution first:

3HFE 1.7 Å, A trimeric form of the Kv7.1 A domain Tail
3BJ4 2.0 Å, The KCNQ1 (Kv7.1) C-terminus, a multi-tiered scaffold for subunit assembly and protein…
7VVH 2.3 Å, Crystal Structure of the Kv7.1 C-terminal Domain in Complex with Calmodulin disease…
3HFC 2.45 Å, A trimeric form of the Kv7.1 A domain Tail, L602M/L606M mutant Semet
7XNN 2.5 Å, human KCNQ1-CaM-ML277-PIP2 complex in state B
9UJ4 2.59 Å, Structure of human KCNQ1-CaM complex
7XNK 2.6 Å, human KCNQ1-CaM in complex with ML277
7VUO 2.68 Å, Crystal Structure of the Kv7.1 C-terminal Domain in Complex with Calmodulin disease…
9VEC 2.7 Å, structure of human KCNQ1-KCNE1-CaM complex
4V0C 2.86 Å, Crystal Structure of the Kv7.1 proximal C-terminal Domain in Complex with Calmodulin
8SIK 2.9 Å, KCNQ1 with voltage sensor in the up conformation
9U7F 2.9 Å, structure of human KCNQ1-KCNE1-CaM complex

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