9UJ4: Human KCNQ1-CaM complex

Structure of human KCNQ1-CaM complex. Determined by electron microscopy at 2.59 Å resolution. Released 22 Apr 2026.

Method: Electron microscopy
Resolution: 2.59 Å
Organism: Homo sapiens
Chains: 8
Atoms: 15,968
Mol. weight: 370.25 kDa
Ligands: PC1, CA
Released: 22 Apr 2026

Explore 9UJ4 in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9UJ4 contains 103 α-helices and 16 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.

Chains A, C, E and G: 17 helices, 0 β-strands

Element	Residues	Length
α-helix	105-115	11
α-helix	121-143	23
α-helix	146-177	32
α-helix	178-180	3
α-helix	187-194	8
α-helix	197-216	20
α-helix	227-236	10
α-helix	237-239	3
α-helix	246-257	12
α-helix	259-284	26
α-helix	299-310	12
α-helix	323-335	13
α-helix	342-358	17
α-helix	367-383	17
α-helix	392-395	4
α-helix	508-532	25
α-helix	538-563	26

Chain B: 8 helices, 4 β-strands

Element	Residues	Length	Sheet
α-helix	7-20	14
β-strand	27-28	2	1
α-helix	30-40	11
α-helix	46-54	9
β-strand	64-65	2	1
α-helix	66-74	9
α-helix	81-91	11
β-strand	100-102	3	2
α-helix	103-112	10
α-helix	119-127	9
β-strand	136-138	3	2
α-helix	139-148	10

Chains D, F and H: 9 helices, 4 β-strands

Element	Residues	Length	Sheet
α-helix	7-20	14
β-strand	27-28	2	7
α-helix	30-40	11
α-helix	46-54	9
β-strand	64-65	2	7
α-helix	66-74	9
α-helix	81-91	11
β-strand	100-102	3	8
α-helix	103-112	10
α-helix	116-118	3
α-helix	119-127	9
β-strand	136-138	3	8
α-helix	139-148	10

Molecules and chains

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

Sequence of entity 1 (A, C, E, G), FASTA

>9UJ4_1 Potassium voltage-gated channel subfamily KQT member 1 (chains A, C, E, G)
MAAASSPPRAERKRWGWGRLPGARRGSAGLAKKCPFSLELAEGGPAGGALYAPIAPGAPG
PAPPASPAAPAAPPVASDLGPRPPVSLDPRVSIYSTRRPVLARTHVQGRVYNFLERPTGW
KCFVYHFAVFLIVLVCLIFSVLSTIEQYAALATGTLFWMEIVLVVFFGTEYVVRLWSAGC
RSKYVGLWGRLRFARKPISIIDLIVVVASMVVLCVGSKGQVFATSAIRGIRFLQILRMLH
VDRQGGTWRLLGSVVFIHRQELITTLYIGFLGLIFSSYFVYLAEKDAVNESGRVEFGSYA
DALWWGVVTVTTIGYGDKVPQTWVGKTIASCFSVFAISFFALPAGILGSGFALKVQQKQR
QKHFNRQIPAAASLIQTAWRCYAAENPDSSTWKIYIRKAPRSHTLLSPSPKPKKSVVVKK
KKFKLDKDNGVTPGEKMLTVPHITCDPPEERRLDHFSVDGYDSSVRKSPTLLEVSMPHFM
RTNSFAEDLDLEGETLLTPITHISQLREHHRATIKVIRRMQYFVAKKKFQQARKPYDVRD
VIEQYSQGHLNLMVRIKELQRRLDQSIGKPSLFISVSEKSKDRGSNTIGARLNRVEDKVT
QLDQRLALITDMLHQLLSLHGGSTPGSGGPPREGGAHITQPCGSGGSVDPELFLPSNTLP
TYEQLTVPRRGPDEGS

Sequence of entity 2 (B, D, F, H), FASTA

>9UJ4_2 Calmodulin-1 (chains B, D, F, H)
MADQLTEEQIAEFKEAFSLFDKDGDGTITTKELGTVMRSLGQNPTEAELQDMINEVDADG
NGTIDFPEFLTMMARKMKDTDSEEEIREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDE
EVDEMIREADIDGDGQVNYEEFVQMMTAK

Ligands and cofactors

ID	Name	Formula	Copies
PC1	1,2-diacyl-sn-glycero-3-phosphocholine	C44 H88 N O8 P	4
CA	Calcium ion	Ca	8

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

Primary citation

Structure of human KCNQ1-CaM complex. Hou, P.P., Zhang, J., Cheng, X.Y. et al. To be published.

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
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
4UMO 3.0 Å, Crystal Structure of the Kv7.1 proximal C-terminal Domain in Complex with Calmodulin

Browse structure collections

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