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B7U540 (KCJ18_HUMAN) Reviewed, UniProtKB/Swiss-Prot

Last modified May 14, 2014. Version 44. Feed History...

Clusters with 100%, 90%, 50% identity | Documents (5) | Third-party data text xml rdf/xml gff fasta
to top of pageNames·Attributes·General annotation·Ontologies·Sequence annotation·Sequences·References·Cross-refs·Entry info·DocumentsCustomize order

Names and origin

Protein namesRecommended name:
Inward rectifier potassium channel 18
Alternative name(s):
Inward rectifier K(+) channel Kir2.6
Potassium channel, inwardly rectifying subfamily J member 18
Gene names
Name:KCNJ18
OrganismHomo sapiens (Human) [Reference proteome]
Taxonomic identifier9606 [NCBI]
Taxonomic lineageEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresPrimatesHaplorrhiniCatarrhiniHominidaeHomo

Protein attributes

Sequence length433 AA.
Sequence statusComplete.
Protein existenceEvidence at protein level

General annotation (Comments)

Function

Inward rectifier potassium channels are characterized by a greater tendency to allow potassium to flow into the cell rather than out of it. Their voltage dependence is regulated by the concentration of extracellular potassium; as external potassium is raised, the voltage range of the channel opening shifts to more positive voltages. The inward rectification is mainly due to the blockage of outward current by internal magnesium. Ref.1

Subcellular location

Cell membrane; Multi-pass membrane protein Probable.

Tissue specificity

Specifically expressed in skeletal muscle. Ref.1

Induction

Up-regulated by triiodothyronine. Ref.1

Post-translational modification

Probably phosphorylated by PKC; decreases single-channel open probability. Ref.1

Involvement in disease

Thyrotoxic periodic paralysis 2 (TTPP2) [MIM:613239]: A sporadic muscular disorder characterized by episodic weakness and hypokalemia during a thyrotoxic state. It is clinically similar to hereditary hypokalemic periodic paralysis, except for the fact that hyperthyroidism is an absolute requirement for disease manifestation. The disease presents with recurrent episodes of acute muscular weakness of the four extremities that vary in severity from paresis to complete paralysis. Attacks are triggered by ingestion of a high carbohydrate load or strenuous physical activity followed by a period of rest. Thyrotoxic periodic paralysis can occur in association with any cause of hyperthyroidism, but is most commonly associated with Graves disease.
Note: Disease susceptibility is associated with variations affecting the gene represented in this entry. Ref.1

Sequence similarities

Belongs to the inward rectifier-type potassium channel (TC 1.A.2.1) family. KCNJ12 subfamily. [View classification]

Ontologies

Keywords
   Biological processIon transport
Potassium transport
Transport
   Cellular componentCell membrane
Membrane
   Coding sequence diversityPolymorphism
   DiseaseDisease mutation
   DomainTransmembrane
Transmembrane helix
   LigandPotassium
   Molecular functionIon channel
Voltage-gated channel
   PTMPhosphoprotein
   Technical termComplete proteome
Reference proteome
Gene Ontology (GO)
   Biological_processpotassium ion transmembrane transport

Inferred from direct assay Ref.1. Source: GOC

   Cellular_componentintegral component of membrane

Inferred from electronic annotation. Source: UniProtKB-KW

plasma membrane

Inferred from direct assay Ref.1. Source: UniProtKB

   Molecular_functioninward rectifier potassium channel activity

Inferred from direct assay Ref.1. Source: UniProtKB

Complete GO annotation...

Sequence annotation (Features)

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifier

Molecule processing

Chain1 – 433433Inward rectifier potassium channel 18
PRO_0000395171

Regions

Topological domain1 – 8484Cytoplasmic Potential
Transmembrane85 – 10521Helical; Potential
Topological domain106 – 15651Extracellular Potential
Transmembrane157 – 17721Helical; Potential
Topological domain178 – 433256Cytoplasmic Potential

Natural variations

Natural variant1401T → M in TTPP2. Ref.1
VAR_063286
Natural variant2051R → H in TTPP2; hypermorphic; longer time required for half-maximal current degradation. Ref.1
VAR_063287
Natural variant3541T → M in TTPP2; small decrease in current density. Ref.1
VAR_063288
Natural variant3661K → R in TTPP2; hypermorphic; longer time required for half-maximal current degradation. Ref.1
VAR_063289

Experimental info

Mutagenesis3541T → E: Decreases the single-channel open probability (Po) without altering its conductance. Ref.1

Sequences

Sequence LengthMass (Da)Tools
B7U540 [UniParc].

Last modified December 15, 2009. Version 2.
Checksum: 04FC98656CD046D1

FASTA43348,738
        10         20         30         40         50         60 
MTAASQANPY SIVSLEEDGL HLVTMSGAKG FGNGKVHTQH RCRNRFVKKN GQCNIAFANM 

        70         80         90        100        110        120 
DEKSQRYLAD MFTTCVDIRW RYMLLIFSLA FLASWLLFGV IFWVIAVAHG DLEPAEGHGR 

       130        140        150        160        170        180 
TPCVMQVHGF MAAFLFSIET QTTIGYGLRC VTEECLVAVF MVVAQSIVGC IIDSFMIGAI 

       190        200        210        220        230        240 
MAKMARPKKR AHTLLFSHNA VVALRDGKLC LMWRVGNLRK SHIVEAHVRA QLIKPRVTEE 

       250        260        270        280        290        300 
GEYIPLDQVD IDVGFDKGLD RIFLVSPITI LHEIDEASPL LGISRQDLET DDFEIVVILE 

       310        320        330        340        350        360 
GMVEATAMTT QARSSYLANE ILWGHRFEPV LFEEKNQFKI DHSHFHKTYE VPSTPRCSAK 

       370        380        390        400        410        420 
DLVENKFLLP SANSFCYENE LAFLSRDEED EADGDQDGRS RDGLSPQARH DFDRLQAGGG 

       430 
VLEQRPYRRG SEI 

« Hide

References

[1]"Mutations in potassium channel Kir2.6 cause susceptibility to thyrotoxic hypokalemic periodic paralysis."
Ryan D.P., da Silva M.R., Soong T.W., Fontaine B., Donaldson M.R., Kung A.W., Jongjaroenprasert W., Liang M.C., Khoo D.H., Cheah J.S., Ho S.C., Bernstein H.S., Maciel R.M., Brown R.H. Jr., Ptacek L.J.
Cell 140:88-98(2010) [PubMed] [Europe PMC] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [MRNA], FUNCTION, INDUCTION BY TRIIODOTHYRONINE, TISSUE SPECIFICITY, PHOSPHORYLATION, VARIANTS TTPP2 MET-140; HIS-205; MET-354 AND ARG-366, CHARACTERIZATION OF VARIANTS TTPP2 HIS-205; MET-354 AND ARG-366, MUTAGENESIS OF THR-354.
Tissue: Brain.
+Additional computationally mapped references.

Cross-references

Sequence databases

EMBL
GenBank
DDBJ
FJ434338 mRNA. Translation: ACJ64506.2.
UniGeneHs.200629.

3D structure databases

ProteinModelPortalB7U540.
SMRB7U540. Positions 42-372.
ModBaseSearch...
MobiDBSearch...

Protein-protein interaction databases

BioGrid936647. 1 interaction.

Proteomic databases

PRIDEB7U540.

Protocols and materials databases

StructuralBiologyKnowledgebaseSearch...

Organism-specific databases

GeneCardsGC17P8V0344.
HGNCHGNC:39080. KCNJ18.
HPAHPA027021.
MIM613236. gene.
613239. phenotype.
neXtProtNX_B7U540.
Orphanet79102. Thyrotoxic periodic paralysis.
GenAtlasSearch...

Phylogenomic databases

HOVERGENHBG006178.
PhylomeDBB7U540.

Family and domain databases

Gene3D2.60.40.1400. 1 hit.
InterProIPR014756. Ig_E-set.
IPR016449. K_chnl_inward-rec_Kir.
IPR003272. K_chnl_inward-rec_Kir2.2.
IPR013518. K_chnl_inward-rec_Kir_cyto.
IPR013673. K_chnl_inward-rec_Kir_N.
[Graphical view]
PANTHERPTHR11767. PTHR11767. 1 hit.
PTHR11767:SF14. PTHR11767:SF14. 1 hit.
PfamPF01007. IRK. 1 hit.
PF08466. IRK_N. 1 hit.
[Graphical view]
PIRSFPIRSF005465. GIRK_kir. 1 hit.
PRINTSPR01325. KIR22CHANNEL.
PR01320. KIRCHANNEL.
SUPFAMSSF81296. SSF81296. 1 hit.
ProtoNetSearch...

Other

NextBio33696320.
PROB7U540.
SOURCESearch...

Entry information

Entry nameKCJ18_HUMAN
AccessionPrimary (citable) accession number: B7U540
Entry history
Integrated into UniProtKB/Swiss-Prot: July 13, 2010
Last sequence update: December 15, 2009
Last modified: May 14, 2014
This is version 44 of the entry and version 2 of the sequence. [Complete history]
Entry statusReviewed (UniProtKB/Swiss-Prot)
Annotation programChordata Protein Annotation Program
DisclaimerAny medical or genetic information present in this entry is provided for research, educational and informational purposes only. It is not in any way intended to be used as a substitute for professional medical advice, diagnosis, treatment or care.

Relevant documents

SIMILARITY comments

Index of protein domains and families

MIM cross-references

Online Mendelian Inheritance in Man (MIM) cross-references in UniProtKB/Swiss-Prot

Human polymorphisms and disease mutations

Index of human polymorphisms and disease mutations

Human entries with polymorphisms or disease mutations

List of human entries with polymorphisms or disease mutations

Human chromosome 17

Human chromosome 17: entries, gene names and cross-references to MIM