6CNM: Human SK4/calmodulin channel complex

Cryo-EM structure of the human SK4/calmodulin channel complex. Determined by electron microscopy at 3.4 Å resolution. Released 2 May 2018.

Method: Electron microscopy
Resolution: 3.4 Å
Organism: Homo sapiens
Chains: 8
Atoms: 12,541
Mol. weight: 265.76 kDa
Ligands: LMT, POV
Released: 2 May 2018

Explore 6CNM in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

6CNM contains 76 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.

Chains A, B and C: 15 helices, 0 β-strands

Element	Residues	Length
α-helix	12-50	39
α-helix	57-91	35
α-helix	96-99	4
α-helix	104-114	11
α-helix	149-154	6
α-helix	157-161	5
α-helix	162-170	9
α-helix	177-186	10
α-helix	192-202	11
α-helix	204-226	23
α-helix	237-248	12
α-helix	261-287	27
α-helix	293-330	38
α-helix	338-368	31
α-helix	370-384	15

Chain D: 15 helices, 0 β-strands

Element	Residues	Length
α-helix	12-50	39
α-helix	57-91	35
α-helix	96-99	4
α-helix	104-114	11
α-helix	149-154	6
α-helix	157-161	5
α-helix	162-170	9
α-helix	177-186	10
α-helix	192-202	11
α-helix	204-226	23
α-helix	237-248	12
α-helix	261-287	27
α-helix	293-330	38
α-helix	338-368	31
α-helix	370-383	14

Chains E, F, G and H: 4 helices, 2 β-strands

Element	Residues	Length	Sheet
α-helix	82-89	8
β-strand	99-101	3	1
α-helix	102-111	10
α-helix	118-128	11
β-strand	135-137	3	1
α-helix	138-145	8

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Intermediate conductance calcium-activated potassium channel protein 4	A, B, C, D	protein	427	Homo sapiens	O15554 (AlphaFold model)
Calmodulin-1	E, F, G, H	protein	149	Homo sapiens	P0DP23 (AlphaFold model)

Sequence of entity 1 (A, B, C, D), FASTA

>6CNM_1 Intermediate conductance calcium-activated potassium channel protein 4 (chains A, B, C, D)
MGGDLVLGLGALRRRKRLLEQEKSLAGWALVLAGTGIGLMVLHAEMLWFGGCSWALYLFL
VKCTISISTFLLLCLIVAFHAKEVQLFMTDNGLRDWRVALTGRQAAQIVLELVVCGLHPA
PVRGPPCVQDLGAPLTSPQPWPGFLGQGEALLSLAMLLRLYLVPRAVLLRSGVLLNASYR
SIGALNQVRFRHWFVAKLYMNTHPGRLLLGLTLGLWLTTAWVLSVAERQAVNATGHLSDT
LWLIPITFLTIGYGDVVPGTMWGKIVCLCTGVMGVCCTALLVAVVARKLEFNKAEKHVHN
FMMDIQYTKEMKESAARVLQEAWMFYKHTRRKESHAARRHQRKLLAAINAFRQVRLKHRK
LREQVNSMVDISKMHMILYDLQQNLSSSHRALEKQIDTLAGKLDALTELLSTALGPRQLP
EPSQQSK

Sequence of entity 2 (E, F, G, H), FASTA

>6CNM_2 Calmodulin-1 (chains E, F, G, H)
MADQLTEEQIAEFKEAFSLFDKDGDGTITTKELGTVMRSLGQNPTEAELQDMINEVDADG
NGTIDFPEFLTMMARKMKDTDSEEEIREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDE
EVDEMIREADIDGDGQVNYEEFVQMMTAK

Ligands and cofactors

ID	Name	Formula	Copies
LMT	Dodecyl-beta-D-maltoside	C24 H46 O11	8
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

Activation mechanism of a human SK-calmodulin channel complex elucidated by cryo-EM structures. Lee, C.H., MacKinnon, R. Science (2018) 360:508-513. DOI 10.1126/science.aas9466 · PubMed

Other PDB entries of the same protein (UniProt O15554 (AlphaFold model), which also has an AlphaFold model), best resolution first:

6D42 1.75 Å, Crystal structure of the KCa3.1 C-terminal four-helix bundle (with copper)
9ZRK 2.99 Å, Cryo-EM structure of KCa3.1_I/calmodulin channel in complex with SKA111.
9O48 3.1 Å, Cryo-EM structure of the human SK2-4 chimera/calmodulin channel complex in the Ca2+…
9O5O 3.1 Å, Cryo-EM structure of the human SK2-4 chimera/calmodulin channel complex bound to a small…
9O52 3.18 Å, Cryo-EM structure of the human SK2-4 chimera/calmodulin channel complex bound to the bee…
9O53 3.3 Å, Cryo-EM structure of the human SK2-4 chimera/calmodulin channel complex bound to a small…
9ZRL 3.38 Å, Cryo-EM structure of KCa3.1_II/calmodulin channel in complex with SKA111.
9ZPT 3.39 Å, Cryo-EM structure of KCa3.1_II/calmodulin channel in complex with SKA31.
9O51 3.4 Å, Cryo-EM structure of the human SK2-4 chimera/calmodulin channel complex in the Ca2+ free…
9YDZ 3.4 Å, Cryo EM structure of KCa3.1_R355K_II/calmodulin channel in complex with rimtuzalcap
6CNN 3.5 Å, Cryo-EM structure of the human SK4/calmodulin channel complex in the Ca2+ bound state I
9ED1 3.5 Å, Cryo-EM structure of the human KCa3.1/calmodulin channel in complex with Ca2+ and…

Browse structure collections

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