Hyperpolarization-activated cation channels of the HCN gene family, such as HCN2, contribute to spontaneous rhythmic activity in both heart and brain.[supplied by OMIM, Jul 2010],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 exhibiting weak selectivity for potassium over sodium ions. Contributes to the native pacemaker currents in heart (If) and in neurons (Ih). Produces a large instantaneous current. Activated by cAMP. Modulated by intracellular chloride ions and pH, acidic pH shifts the activation to more negative voltages.,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. Heteromultimer with HCN1. Interacts with KCNE2.,tissue specificity:Highly expressed throughout the brain. Detected at low levels in heart.,
