| Structural highlights
4kl1 is a 4 chain structure with sequence from Human. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
| | Ligands: | , ,
| | NonStd Res: | |
| Related: | 3u0z, 3u10, 3u11, 4hbn, 3otf, 1q3e |
| Gene: | HCN4 (HUMAN) |
| Resources: | FirstGlance, OCA, RCSB, PDBsum |
Disease
[HCN4_HUMAN] Sick sinus syndrome;Brugada syndrome. Sick sinus syndrome 2 (SSS2) [MIM:163800]: The term 'sick sinus syndrome' encompasses a variety of conditions caused by sinus node dysfunction. The most common clinical manifestations are syncope, presyncope, dizziness, and fatigue. Electrocardiogram typically shows sinus bradycardia, sinus arrest, and/or sinoatrial block. Episodes of atrial tachycardias coexisting with sinus bradycardia ('tachycardia-bradycardia syndrome') are also common in this disorder. SSS occurs most often in the elderly associated with underlying heart disease or previous cardiac surgery, but can also occur in the fetus, infant, or child without heart disease or other contributing factors. SSS2 onset is in utero or at birth. Note=The disease is caused by mutations affecting the gene represented in this entry.[1] [2] Brugada syndrome 8 (BRGDA8) [MIM:613123]: A tachyarrhythmia characterized by right bundle branch block and ST segment elevation on an electrocardiogram (ECG). It can cause the ventricles to beat so fast that the blood is prevented from circulating efficiently in the body. When this situation occurs, the individual will faint and may die in a few minutes if the heart is not reset. Note=The disease is caused by mutations affecting the gene represented in this entry.[3]
Function
[HCN4_HUMAN] Hyperpolarization-activated ion channel with very slow activation and inactivation exhibiting weak selectivity for potassium over sodium ions. May contribute to the native pacemaker currents in heart (If) and in neurons (Ih). Activated by cAMP. May mediate responses to sour stimuli.[4] [5]
Publication Abstract from PubMed
cAMP mediates autonomic regulation of heart rate by means of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which underlie the pacemaker current If. cAMP binding to the C-terminal cyclic nucleotide binding domain enhances HCN open probability through a conformational change that reaches the pore via the C-linker. Using structural and functional analysis, we identified a binding pocket in the C-linker of HCN4. Cyclic dinucleotides, an emerging class of second messengers in mammals, bind the C-linker pocket (CLP) and antagonize cAMP regulation of the channel. Accordingly, cyclic dinucleotides prevent cAMP regulation of If in sinoatrial node myocytes, reducing heart rate by 30%. Occupancy of the CLP hence constitutes an efficient mechanism to hinder beta-adrenergic stimulation on If. Our results highlight the regulative role of the C-linker and identify a potential drug target in HCN4. Furthermore, these data extend the signaling scope of cyclic dinucleotides in mammals beyond their first reported role in innate immune system.
Cyclic dinucleotides bind the C-linker of HCN4 to control channel cAMP responsiveness.,Lolicato M, Bucchi A, Arrigoni C, Zucca S, Nardini M, Schroeder I, Simmons K, Aquila M, DiFrancesco D, Bolognesi M, Schwede F, Kashin D, Fishwick CW, Johnson AP, Thiel G, Moroni A Nat Chem Biol. 2014 Jun;10(6):457-62. doi: 10.1038/nchembio.1521. Epub 2014 Apr, 28. PMID:24776929[6]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Milanesi R, Baruscotti M, Gnecchi-Ruscone T, DiFrancesco D. Familial sinus bradycardia associated with a mutation in the cardiac pacemaker channel. N Engl J Med. 2006 Jan 12;354(2):151-7. PMID:16407510 doi:10.1056/NEJMoa052475
- ↑ Laish-Farkash A, Glikson M, Brass D, Marek-Yagel D, Pras E, Dascal N, Antzelevitch C, Nof E, Reznik H, Eldar M, Luria D. A novel mutation in the HCN4 gene causes symptomatic sinus bradycardia in Moroccan Jews. J Cardiovasc Electrophysiol. 2010 Dec;21(12):1365-72. doi:, 10.1111/j.1540-8167.2010.01844.x. PMID:20662977 doi:10.1111/j.1540-8167.2010.01844.x
- ↑ Ueda K, Hirano Y, Higashiuesato Y, Aizawa Y, Hayashi T, Inagaki N, Tana T, Ohya Y, Takishita S, Muratani H, Hiraoka M, Kimura A. Role of HCN4 channel in preventing ventricular arrhythmia. J Hum Genet. 2009 Feb;54(2):115-21. doi: 10.1038/jhg.2008.16. Epub 2009 Jan 23. PMID:19165230 doi:10.1038/jhg.2008.16
- ↑ Ludwig A, Zong X, Stieber J, Hullin R, Hofmann F, Biel M. Two pacemaker channels from human heart with profoundly different activation kinetics. EMBO J. 1999 May 4;18(9):2323-9. PMID:10228147 doi:10.1093/emboj/18.9.2323
- ↑ Seifert R, Scholten A, Gauss R, Mincheva A, Lichter P, Kaupp UB. Molecular characterization of a slowly gating human hyperpolarization-activated channel predominantly expressed in thalamus, heart, and testis. Proc Natl Acad Sci U S A. 1999 Aug 3;96(16):9391-6. PMID:10430953
- ↑ Lolicato M, Bucchi A, Arrigoni C, Zucca S, Nardini M, Schroeder I, Simmons K, Aquila M, DiFrancesco D, Bolognesi M, Schwede F, Kashin D, Fishwick CW, Johnson AP, Thiel G, Moroni A. Cyclic dinucleotides bind the C-linker of HCN4 to control channel cAMP responsiveness. Nat Chem Biol. 2014 Jun;10(6):457-62. doi: 10.1038/nchembio.1521. Epub 2014 Apr, 28. PMID:24776929 doi:http://dx.doi.org/10.1038/nchembio.1521
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