K+/Na+ hyperpolarization-activated cyclic nucleotide-gated channel 2; brain cyclic nucleotide-gated channel 2; BCNG-2 (HCN2 BCNG2)

Function

• hyperpolarization-activated ion channel
• exhibits weak selectivity for K+ over Na+
• contributes to native pacemaker currents in heart (If) & in neurons (Ih)
• produces a large instantaneous current
• activated by cAMP
• modulated by intracellular chloride ions & pH; acidic pH shifts activation to more negative voltages (putative)
• the K+ channel is probably composed of a homo- or heterotetrameric complex of pore-forming subunits
• heteromultimer with HCN1
• interacts with KCNE2 (putative)

Structure

• the segment S4 is probably the voltage-sensor; it is characterized by a series of positively charged amino acids at every third position
• belongs to the K+ channel HCN family
• contains 1 cyclic nucleotide-binding domain

Compartment

membrane

Expression

• highly expressed throughout the brain
• detected at low levels in heart

Notes

• inhibited by extracellular Cs+

More general terms

• hyperpolarization-activated cyclic nucleotide gated K+ channel
• transmembrane 6 protein
• glycoprotein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=610
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:610
• OMIM: https://mirror.omim.org/entry/602781
• UniProt: http://www.uniprot.org/uniprot/Q9UL51.html