HCN4 Polyclonal Antibody

disease:Defects in HCN4 are a cause of sick sinus syndrome type 2 (SSS2) [MIM:163800]; also known as atrial fibrillation with bradyarrhythmia or familial sinus bradycardia. 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, in which case it is considered to be a congenital disorder.,domain:The segment S4 is probably the voltage-sensor and is characterized by a series of positively charged amino acids at every third position.,function: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.,miscellaneous:Inhibited by extracellular cesium ions.,similarity:Belongs to the potassium channel HCN family.,similarity:Contains 1 cyclic nucleotide-binding domain.,subunit:The potassium channel is probably composed of a homo- or heterotetrameric complex of pore-forming subunits.,tissue specificity:Highly expressed in thalamus, testis and in heart, both in ventricle and atrium. Detected at much lower levels in amygdala, substantia nigra, cerebellum and hippocampus.,