3OTF

Structural basis for the cAMP-dependent gating in human HCN4 channel


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.4 Å
  • R-Value Free: 0.275 
  • R-Value Work: 0.237 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Structural basis for the cAMP-dependent gating in the human HCN4 channel.

Xu, X.Vysotskaya, Z.V.Liu, Q.Zhou, L.

(2010) J.Biol.Chem. 285: 37082-37091

  • DOI: 10.1074/jbc.M110.152033

  • PubMed Abstract: 
  • Hyperpolarization-activated cAMP-regulated (HCN) channels play important physiological roles in both cardiovascular and central nervous systems. Among the four HCN isoforms, HCN2 and HCN4 show high expression levels in the human heart, with HCN4 bein ...

    Hyperpolarization-activated cAMP-regulated (HCN) channels play important physiological roles in both cardiovascular and central nervous systems. Among the four HCN isoforms, HCN2 and HCN4 show high expression levels in the human heart, with HCN4 being the major cardiac isoform. The previously published crystal structure of the mouse HCN2 (mHCN2) C-terminal fragment, including the C-linker and the cyclic-nucleotide binding domain (CNBD), has provided many insights into cAMP-dependent gating in HCN channels. However, structures of other mammalian HCN channel isoforms have been lacking. Here we used a combination of approaches including structural biology, biochemistry, and electrophysiology to study cAMP-dependent gating in HCN4 channel. First we solved the crystal structure of the C-terminal fragment of human HCN4 (hHCN4) channel at 2.4 Å. Overall we observed a high similarity between mHCN2 and hHCN4 crystal structures. Functional comparison between two isoforms revealed that compared with mHCN2, the hHCN4 protein exhibited marked different contributions to channel function, such as a ∼3-fold reduction in the response to cAMP. Guided by structural differences in the loop region between β4 and β5 strands, we identified residues that could partially account for the differences in response to cAMP between mHCN2 and hHCN4 proteins. Moreover, upon cAMP binding, the hHCN4 C-terminal protein exerts a much prolonged effect in channel deactivation that could have significant physiological contributions.


    Organizational Affiliation

    Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia 23298, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 4
A
220Homo sapiensMutation(s): 0 
Gene Names: HCN4
Find proteins for Q9Y3Q4 (Homo sapiens)
Go to Gene View: HCN4
Go to UniProtKB:  Q9Y3Q4
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CMP
Query on CMP

Download SDF File 
Download CCD File 
A
ADENOSINE-3',5'-CYCLIC-MONOPHOSPHATE
CYCLIC AMP; CAMP
C10 H12 N5 O6 P
IVOMOUWHDPKRLL-KQYNXXCUSA-N
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
CMPKd: 830 nM BINDINGMOAD
CMPKd: 830 nM PDBBIND
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.4 Å
  • R-Value Free: 0.275 
  • R-Value Work: 0.237 
  • Space Group: I 4 2 2
Unit Cell:
Length (Å)Angle (°)
a = 69.264α = 90.00
b = 69.264β = 90.00
c = 191.616γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
HKL-2000data collection
HKL-2000data scaling
REFMACrefinement
PHASERphasing
HKL-2000data reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2010-10-13
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance