1Q43: PDB entry 1Q43

HCN2I 443-640 in the presence of cAMP, selenomethionine derivative. Determined by X-ray diffraction at 2.0 Å resolution. Released 9 Sept 2003.

Method: X-ray diffraction
Resolution: 2.0 Å
Organism: Mus musculus
Chains: 2
Atoms: 3,526
Mol. weight: 49.79 kDa
Ligands: CMP
Released: 9 Sept 2003

Explore 1Q43 in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

1Q43 contains 23 α-helices and 20 β-strands across 2 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: 12 helices, 10 β-strands

Element	Residues	Length	Sheet
α-helix	444-462	19
α-helix	467-481	15
α-helix	488-494	7
α-helix	497-507	11
α-helix	509-513	5
α-helix	516-519	4
α-helix	523-532	10
β-strand	534-538	5	1
β-strand	543-545	3	2
β-strand	550	1	3
α-helix	551	1
β-strand	553-559	7	1
β-strand	562-565	4	2
β-strand	572-574	3	2
β-strand	579-580	2	1
α-helix	582-587	6
β-strand	590	1	3
β-strand	594-597	4	2
β-strand	601-607	7	1
α-helix	608-617	10
α-helix	619-621	3
α-helix	622-634	13

Chain B: 11 helices, 10 β-strands

Element	Residues	Length	Sheet
α-helix	446-462	17
α-helix	467-481	15
α-helix	488-494	7
α-helix	497-507	11
α-helix	509-513	5
α-helix	516-519	4
α-helix	523-532	10
β-strand	534-538	5	4
β-strand	543-545	3	5
β-strand	550	1	6
β-strand	553-559	7	4
β-strand	562-565	4	5
β-strand	572-574	3	5
β-strand	579-580	2	4
α-helix	582-587	6
β-strand	590	1	6
β-strand	594-597	4	5
β-strand	601-607	7	4
α-helix	608-617	10
α-helix	619-621	3
α-helix	622-634	13

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 2	A, B	protein	207	Mus musculus	O88703 (AlphaFold model)

Sequence of entity 1 (A, B), FASTA

>1Q43_1 Potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 2 (chains A, B)
GSAMDSSRRQYQEKYKQVEQYMSFHKLPADFRQKIHDYYEHRYQGKMFDEDSILGELNGP
LREEIVNFNCRKLVASMPLFANADPNFVTAMLTKLKFEVFQPGDYIIREGTIGKKMYFIQ
HGVVSVLTKGNKEMKLSDGSYFGEICLLTRGRRTASVRADTYCRLYSLSVDNFNEVLEEY
PMMRRAFETVAIDRLDRIGKKNSILLH

Ligands and cofactors

ID	Name	Formula	Copies
CMP	Adenosine-3',5'-cyclic-monophosphate	C10 H12 N5 O6 P	2

Primary citation

Structural basis for modulation and agonist specificity of HCN pacemaker channels. Zagotta, W.N., Olivier, N.B., Black, K.D. et al. Nature (2003) 425:200-205. DOI 10.1038/nature01922 · PubMed

Other PDB entries of the same protein (UniProt O88703 (AlphaFold model), which also has an AlphaFold model), best resolution first:

3BPZ 1.65 Å, HCN2-I 443-460 E502K in the presence of cAMP
5KHH 1.77 Å, HCN2 CNBD in complex with inosine-3', 5'-cyclic monophosphate (cIMP)
1Q3E 1.9 Å, HCN2J 443-645 in the presence of cGMP
3ETQ 1.9 Å, X-ray structure of cysteine-free fragment of mHCN2 C-terminal region from amino acids…
5KHJ 2.01 Å, HCN2 CNBD in complex with uridine-3', 5'-cyclic monophosphate (cUMP)
5JON 2.04 Å, Crystal structure of the unliganded form of HCN2 CNBD
5KHK 2.07 Å, HCN2 CNBD in complex with 2-aminopurine riboside-3', 5'-cyclic monophosphate (2-NH2-cPuMP)
5KHI 2.1 Å, HCN2 CNBD in complex with purine riboside-3', 5'-cyclic monophosphate (cPuMP)
5KHG 2.24 Å, HCN2 CNBD in complex with cytidine-3', 5'-cyclic monophosphate (cCMP)
2Q0A 2.25 Å, Structure and rearrangements in the carboxy-terminal region of SpIH channels
1Q5O 2.3 Å, HCN2J 443-645 in the presence of cAMP, selenomethionine derivative
3FFQ 2.4 Å, HCN2I 443-640 apo-state

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