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