Hyperpolarization Activated Cyclic Nucleotide Gated K+ Channel 4
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Contents |
Function
- hyperpolarization-activated ion channel with very slow activation & inactivation
- exhibits weak selectivity for K+ over Na+
- may contribute to the native pacemaker currents in heart (If) & in neurons (Ih)
- activated by cAMP
- may mediate responses to sour stimuli
- the K+ channel is probably composed of a homo- or heterotetrameric complex of pore-forming subunits
Structure
- the segment S4 is probably the voltage- sensor & 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 in thalamus, testis & in heart, both in ventricle & atrium
- detected at much lower levels in amygdala, substantia nigra, cerebellum & hippocampus
Pathology
- defects in HCN4 are a cause of sick sinus syndrome type 2
- defects in HCN4 are the cause of Brugada syndrome type 8
Notes
- inhibited by extracellular Cs+
More General Terms
- hyperpolarization-activated cyclic nucleotide gated K+ channel
- transmembrane 6 protein
- phosphoprotein
Internet Database
Entrez gene: 10021
Kegg: [1]
OMIM: 163800
OMIM: 605206
OMIM: 613123
Prosite: [2]
Prosite: [3]
Prosite: [4]
UniProt: [5]
References
