2mng

Structural highlights

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]}

See Also

• Ion channels 3D structures

References

1. ↑ 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
2. ↑ 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
3. ↑ 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
4. ↑ 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
5. ↑ 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
6. ↑ Akimoto M, Zhang Z, Boulton S, Selvaratnam R, VanSchouwen B, Gloyd M, Accili EA, Lange OF, Melacini G. A mechanism for the auto-inhibition of hyperpolarization-activated cyclic nucleotide-gated (HCN) channel opening and its relief by cAMP. J Biol Chem. 2014 Aug 8;289(32):22205-20. doi: 10.1074/jbc.M114.572164. Epub 2014, May 30. PMID:24878962 doi:http://dx.doi.org/10.1074/jbc.M114.572164