HCN2 channel
| Channel name | HCN21,2,3 |
| Description | Hyperpolarization-activated cyclic nucleotide-gated cation channel |
| Other names | HAC1, BCNG2 |
| Molecular information | Human: 889aa, NM_001194, NP_00185, chr. 19p13.3 |
| Rat: 834aa, NM_053684, NP_446136, chr. 7q11 | |
| Mouse: 863aa, NM_008226, NP_032252, chr. 10 C1 | |
| Associated subunits | Not established |
| Functional assays | Voltage-clamp |
| Current | Ih, If, or Iq |
| Conductance | Not established |
| Ion selectivity | K+, Na+ (PNa/PK ∼ 0.2); divalents do not permeate |
| Activation | V0.5 = -75 mV to -100 mV; ta = 180–600 ms at -140 mV to -100 mV (values are strongly influenced by experimental parameters such as temperature, pH, and pulse protocol) |
| Inactivation | No inactivation |
| Activators | cAMP > cGMP (both induce a positive shift of V0.5 by ∼ +15mV) |
| Gating modifiers | ZD7288 |
| Blockers | Cs+, ZD7288, ivabradine, zatebradine, cilobradine |
| Radioligands | None |
| Channel distribution | Central and peripheral neurones, retina, heart cells |
| Physiological functions | Resting membrane potential of neurons and cardiac pacemaker cells, modulation of firing mode of thalamic neurons |
| Mutations and pathophysiology | Not established in humans |
| Pharmacological significance | Not established |
aa, amino acids; chr., chromosome.
↵1. Ludwig A, Zong X, Jeglitsch M, Hofmann F, and Biel M (1998) A family of hyperpolarization-activated mammalian cation channels. Nature (Lond) 393:587-591
↵2. Ludwig A, Zong X, Stieber J, Hullin R, Hofmann F, and Biel M (1999) Two pacemaker channels from human heart with profoundly different activation kinetics. EMBO J 18:2323-2329
↵3. Monteggia LM, Eisch AJ, Tang MD, Kaczmarek LK, and Nestler EJ (2000) Cloning and localization of the hyperpolarization-activated cyclic nucleotide-gated channel family in rat brain. Brain Res Mol Brain Res 81:129-139