Seroatlas · Human Serome Atlas

KCNJ3

G protein-activated inward rectifier potassium channel 1

Also known as: GIRK1, KCNJ3_HUMAN, KGA, Kir3.1

Cross-references: UniProt · Ensembl · Human Protein Atlas · GeneCards · NCBI Gene

Protein identityUniProt · HPA

UniProt accession
P48549
Gene
KCNJ3
Ensembl
ENSG00000162989
Chromosome
2
Canonical length
501 aa
Protein class
FDA approved drug targets, Plasma proteins, Predicted intracellular proteins, Predicted membrane proteins, Transporters, Voltage-gated ion channels
Subcellular location
Plasma membrane,Mitochondria

OverviewNCBI Gene

Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. The protein encoded by this gene is an integral membrane protein and inward-rectifier type potassium channel. The encoded protein, which has a greater tendency to allow potassium to flow into a cell rather than out of a cell, is controlled by G-proteins and plays an important role in regulating heartbeat. It associates with three other G-protein-activated potassium channels to form a heteromultimeric pore-forming complex that also couples to neurotransmitter receptors in the brain and whereby channel activation can inhibit action potential firing by hyperpolarizing the plasma membrane. These multimeric G-protein-gated inwardly-rectifying potassium (GIRK) channels may play a role in the pathophysiology of epilepsy, addiction, Down's syndrome, ataxia, and Parkinson's disease. Alternative splicing results in multiple transcript variants encoding distinct proteins. [provided by RefSeq, May 2012]

Canonical amino-acid sequenceUniProt

501 residues, UniProt reviewed canonical sequence.

>P48549|KCNJ3
     1  MSALRRKFGD DYQVVTTSSS GSGLQPQGPG QDPQQQLVPK KKRQRFVDKN GRCNVQHGNL
    61  GSETSRYLSD LFTTLVDLKW RWNLFIFILT YTVAWLFMAS MWWVIAYTRG DLNKAHVGNY
   121  TPCVANVYNF PSAFLFFIET EATIGYGYRY ITDKCPEGII LFLFQSILGS IVDAFLIGCM
   181  FIKMSQPKKR AETLMFSEHA VISMRDGKLT LMFRVGNLRN SHMVSAQIRC KLLKSRQTPE
   241  GEFLPLDQLE LDVGFSTGAD QLFLVSPLTI CHVIDAKSPF YDLSQRSMQT EQFEIVVILE
   301  GIVETTGMTC QARTSYTEDE VLWGHRFFPV ISLEEGFFKV DYSQFHATFE VPTPPYSVKE
   361  QEEMLLMSSP LIAPAITNSK ERHNSVECLD GLDDITTKLP SKLQKITGRE DFPKKLLRMS
   421  STTSEKAYSL GDLPMKLQRI SSVPGNSEEK LVSKTTKMLS DPMSQSVADL PPKLQKMAGG
   481  AARMEGNLPA KLRKMNSDRF T

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against KCNJ3 can act on the native protein depends on physical access: surface and secreted proteins are reachable by circulating antibodies, intracellular proteins usually are not.

Antibody reachability
Cell surface
Secreted
No
Transmembrane segments
2
Mean surface accessibility (rSASA)
0.46
Highest tissue expression
39 nTPM

Expression across tissuesHPA

Tissue

  • cerebellum: 39 nTPM
  • cerebral cortex: 16 nTPM
  • heart muscle: 14 nTPM
  • seminal vesicle: 11 nTPM
  • duodenum: 10 nTPM
  • kidney: 9.8 nTPM

Single-cell type

  • corticotrophs: 996 nCPM
  • thyrotrophs: 724 nCPM
  • lactotrophs: 643 nCPM
  • brain excitatory neurons: 579 nCPM
  • retinal horizontal cells: 565 nCPM
  • choroid plexus epithelial cells: 561 nCPM

Immune cell

  • basophil: 0.9 nTPM
  • neutrophil: 0.3 nTPM
  • NK-cell: 0.3 nTPM
  • naive B-cell: 0.2 nTPM
  • non-classical monocyte: 0.2 nTPM
  • classical monocyte: 0.1 nTPM

Brain region

  • cerebellum: 89 nTPM
  • cerebral cortex: 56 nTPM
  • hippocampal formation: 51 nTPM
  • basal ganglia: 35 nTPM
  • white matter: 33 nTPM
  • choroid plexus: 28 nTPM

Genetic constraint and essentialitygnomAD · DepMap

Does the body need this protein intact? Low LOEUF or a strong DepMap dependency means loss or blockade of the protein is likely to be felt.

gnomAD LOEUF (loss-of-function intolerance)
0.26
gnomAD pLI
0.99
gnomAD missense Z
4.06
DepMap mean gene effect
-0.01
DepMap dependency class
selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 3% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Molecular functions

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads KCNJ3 as an antibody target. Whether an autoantibody or antibody against KCNJ3 could matter depends on whether native KCNJ3 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

KCNJ3 is annotated at the cell surface, where native KCNJ3 is exposed to circulating antibodies and is a prime autoantibody target that could block, deplete, or overstimulate it.

Annotation status

The present source text does not explicitly label KCNJ3 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/KCNJ3. Study-independent annotations aggregated from UniProt, Human Protein Atlas, PubMed, IEDB, Pfam, InterPro, Gene Ontology, AlphaFold, gnomAD, DepMap, ClinVar, TCGA. Catalog release seroatlas-reviewed-human-uniprot-20260313.

Seroatlas is the reference for exploring autoantibody and antibody serology at the human-protein level: the autoreactome and human serome, multiplex serology (HuProt, HuScan, VirScan, PhIP-Seq).

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