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0HCN3_HUMAN*   SwissProt (?) | Description Local Annotation Link Reference
General Information
DescriptionPotassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 3.
SpeciesHomo sapiens (NCBI taxonomy ID: 9606)
Domain Architecture (Details)
InterPro domains assigned to SynO:
Potassium channels are the most diverse group of the ion channel family. They are important in shaping the action potential.nd in neuronal excitability and plasticity . The potassium channel family iscomposed of several functionally distinct isoforms.hich can be broadlyseparated into 2 groups : the practically non-inactivating delayed group and the rapidly inactivating transient group.These are all highly similar proteins.ith only small amino acidchanges causing the diversity of the voltage-dependent gating mechanism.hannel conductance and toxin binding properties. Each type of K+ channel is activated by different signals and conditions depending on their type of regulation: some open in response to depolarisation of the plasma membrane; others in response to hyperpolarisation or an increase in intracellular calcium concentration; some can be regulated by binding of a transmitter.ogether with intracellular kinases; and others are regulated by GTP-binding proteins orother second messengers . In eukaryotic cells.+ channelsare involved in neural signalling and generation of the cardiac rhythm.ct as effectors in signal transduction pathways involving G protein-coupled receptors (GPCRs) and may have a role in target cell lysis by cytotoxic T-lymphocytes . In prokaryotic cells.hey play a role in themaintenance of ionic homeostasis . All K+ channels discovered so far possess a core of alpha subunits.ach comprising either one or two copies of a highly conserved pore loop domain (P-domain). The P-domain contains the sequence (T/SxxTxGxG).hich hasbeen termed the K+ selectivity sequence.In families that contain one P-domain.our subunits assemble to form a selective pathway for K+ across the membrane.However.t remains unclear how the 2 P-domain subunits assemble to form a selective pore. The functional diversity of these families can arise through homo- or hetero-associations of alpha subunits or association with auxiliary cytoplasmic beta subunits. K+ channel subunits containing one pore domain can be assigned into one of two superfamilies: those that possess six transmembrane (TM) domains and those that possess only two TM domains. The six TM domain superfamily can be further subdivided into conserved gene families: the voltage-gated (Kv) channels; the KCNQ channels (originally known as KvLQT channels); the EAG-like K+ channels; and three types of calcium (Ca)-activated K+ channels (BK.K and SK). The 2TM domain family comprises inward-rectifying K+ channels. In are K+ channel alpha-subunits that possess two P-domains. These are usually highly regulated K+ selective leak channels.The first EAG K+ channel was identified in Drosophila melanogaster.ollowing a screen for mutations giving rise to behavioural abnormalities. Disruption of the Eag gene caused an behaviour. Subsequent studies have revealed a conserved multi-gene family of EAG-like K+ channels.hich are present in human and many other species. Based on the varying functional properties of the channels.he family has been divided into 3 subfamilies: EAG.LK and ERG. Interestingly.aenorhabditis elegans appears to lack the ELK type .
  IPR003938:EAG/ELK/ERG potassium channel
InterPro domains unassigned to SynO:
This metazoan domain is found to the N terminus of in voltage- and cyclic nucleotide-gated K/Na ion channels.
  IPR013621:Ion transport N-terminal
Proteins that bind cyclic nucleotides (cAMP or cGMP) share a structural domain of about 120 residues . The best studied of these proteins is the prokaryotic catabolite gene activator (alsoknown as the cAMP receptor protein) (gene crp) where such a domain is known to be composed of three alpha-helices anda distinctive eight-stranded.ntiparallel beta-barrel structure. There are six invariant amino acids in this domain.hree of which are glycine residues that are thought to be essential for maintenance of the structural integrity ofthe beta-barrel. cAMP- and cGMP-dependent protein kinases (cAPK and cGPK) contain two tandem copies of the cyclicnucleotide-binding domain. The cAPKs are composed of two different subunits. catalytic chain and a regulatory chain.hich contains both copies of the domain. The cGPKs are single chain enzymes that include the two copies of the domainin their N-terminal section. Vertebrate cyclic nucleotide-gated ion-channels also contain this domain. Two suchcations channels have been fully is found in rod cells where it plays a role in visual signaltransduction.
  IPR000595:Cyclic nucleotide-binding
This group of proteins is found in sodium.otassium.nd calcium ion channels proteins. The proteins have 6 transmembrane helices in which the last two helices flank a loop which determines ion selectivity. In some Na channels proteins the domain is repeated four times.hereas in others (e.g. K channels) the protein forms a tetramer in the membrane. A bacterial structure of the protein is known for the last two helices but is not included in the Pfam family due to it lacking the first four helices.
  IPR005821:Ion transport
SequencesProtein: HCN3_HUMAN (774 aa)
mRNA: NM_020897
Local Annotation
Synapse Ontology
this kind of receptor usually locates at the postsynaptic plasma membranous region.
sdb:0109 ionotropic receptor  (Evidence:keywords,domains)
sdb:0219 GPCR mediated signaling  (Evidence:keywords,domains)
LTP that is not dependent on the function of NMDA receptor.
sdb:0255 NMDA Receptor-independent LTP  (Evidence:keywords,domains)
K channel plays an important role in the course of action potential
sdb:0286 K channel  (Evidence:keywords,domains)
Na channel plays an important role in the course of action potential.
sdb:0287 Na channel  (Evidence:keywords,domains)
all kinds of ion channels that play their roles in the synaptic activity.
sdb:0308 ion channels and receptors  (Evidence:keywords,domains)
KO assignmentK04956
  Level 3 annotation:
    hyperpolarization activated cyclic nucleotide-gated potassium channel 3
  Level 2 annotation:
    Ion channels
Loci Structure (Details)Loci index, Chromosomal location, Length, Possible relational loci clusterExon1: 96 residues, 153513997-153514283Exon2: 145 residues, 153518825-153519255Exon3: 56 residues, 153520388-153520550Exon4: 75 residues, 153520953-153521172Exon5: 51 residues, 153521579-153521726Exon6: 82 residues, 153522138-153522379Exon7: 57 residues, 153523587-153523752Exon8: 691 residues, 153524195-153526262Exon9: 2 residues, -Jump to HCN3_HUMAN  
Tune and view alternative isoforms
Loci Cluster (Details)Loci: 3833 152220753-152225430 ~-5K 2681(RAB13)(-)Loci: 2551 152511662-152514973 ~-3K 2706(HAX1)(+)Loci: 2552 152806880-152815707 ~-9K 2720(CHRNB2)(+)Loci: 3834 152821158-152847306 ~-26K 2722(ADAR)(-)Loci: 3835 153201398-153209847 ~-8K 2739(SHC1)(-)Loci: 2553 153412983-153424069 ~-11K 2783(TRIM46)(+)Loci: 2554 153513997-153526262 ~-12K 2831(HCN3)(+)Loci: 3836 153526253-153537835 ~-12K 2833(PKLR)(-)Loci: 2555 153669594-153670676 ~-1K 2846(POU5FLC1)(+)Loci: 2556 154095923-154121459 ~-26K 2875(SYT11)(+)Loci: 3837 154183269-154214942 ~-32K 2882(ARHGEF2)(-)Loci: 2557 154297589-154306917 ~-9K 2890(RAB25)(+)Loci: 2558 154362603-154374280 ~-12K 2897(+)Loci: 2559 154855709-154862142 ~-6K 2944(HAPLN2)(+)Loci: 2560 154878363-154895942 ~-18K 2945(BCAN)(+)Loci: 3838 154905181-154913813 ~-9K 2947(NES)(-)Loci: 2561 155097294-155118266 ~-21K 2961(NTRK1)(+)Loci: 3839 155171256-155281786 ~-111K 2965(ARHGEF11)(-)Loci: 2550 151897823-151900928 ~-3K 2658(SNAPAP)(+)Link out to UCSC