Seroatlas · Human Serome Atlas

KCNJ4

Inward rectifier potassium channel 4

Also known as: HIR, hIRK2, HRK1, IRK3, KCNJ4_HUMAN, Kir2.3

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

Protein identityUniProt · HPA

UniProt accession: P48050
Gene: KCNJ4
Ensembl: ENSG00000168135
Chromosome: 22
Canonical length: 445 aa
Protein class: FDA approved drug targets, Predicted membrane proteins, Transporters, Voltage-gated ion channels

OverviewNCBI Gene

Several different potassium channels are known to be involved with electrical signaling in the nervous system. One class is activated by depolarization whereas a second class is not. The latter are referred to as inwardly rectifying K+ channels, and they have a greater tendency to allow potassium to flow into the cell rather than out of it. This asymmetry in potassium ion conductance plays a key role in the excitability of muscle cells and neurons. The protein encoded by this gene is an integral membrane protein and member of the inward rectifier potassium channel family. The encoded protein has a small unitary conductance compared to other members of this protein family. Two transcript variants encoding the same protein have been found for this gene. [provided by RefSeq, Jul 2008]

Canonical amino-acid sequenceUniProt

445 residues, UniProt reviewed canonical sequence.

>P48050|KCNJ4
     1  MHGHSRNGQA HVPRRKRRNR FVKKNGQCNV YFANLSNKSQ RYMADIFTTC VDTRWRYMLM
    61  IFSAAFLVSW LFFGLLFWCI AFFHGDLEAS PGVPAAGGPA AGGGGAAPVA PKPCIMHVNG
   121  FLGAFLFSVE TQTTIGYGFR CVTEECPLAV IAVVVQSIVG CVIDSFMIGT IMAKMARPKK
   181  RAQTLLFSHH AVISVRDGKL CLMWRVGNLR KSHIVEAHVR AQLIKPYMTQ EGEYLPLDQR
   241  DLNVGYDIGL DRIFLVSPII IVHEIDEDSP LYGMGKEELE SEDFEIVVIL EGMVEATAMT
   301  TQARSSYLAS EILWGHRFEP VVFEEKSHYK VDYSRFHKTY EVAGTPCCSA RELQESKITV
   361  LPAPPPPPSA FCYENELALM SQEEEEMEEE AAAAAAVAAG LGLEAGSKEE AGIIRMLEFG
   421  SHLDLERMQA SLPLDNISYR RESAI

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against KCNJ4 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): 0.41
Highest tissue expression: 83 nTPM

Expression across tissuesHPA

Tissue

cerebral cortex: 83 nTPM
basal ganglia: 55 nTPM
heart muscle: 32 nTPM
amygdala: 31 nTPM
hippocampal formation: 31 nTPM
hypothalamus: 7.3 nTPM

Single-cell type

platelets: 14 nCPM
brain inhibitory neurons: 13 nCPM
ependymal cells: 12 nCPM
brain excitatory neurons: 11 nCPM
cardiomyocytes: 8.5 nCPM
müller glia: 6.9 nCPM

Immune cell

basophil: 0 nTPM
classical monocyte: 0 nTPM
eosinophil: 0 nTPM
gdT-cell: 0 nTPM
intermediate monocyte: 0 nTPM
MAIT T-cell: 0 nTPM

Brain region

cerebral cortex: 85 nTPM
hippocampal formation: 70 nTPM
basal ganglia: 63 nTPM
amygdala: 47 nTPM
white matter: 46 nTPM
hypothalamus: 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): 0.29
gnomAD pLI: 0.96
gnomAD missense Z: 3.97
DepMap mean gene effect: -0.15
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

InteractionsUniProt · HPA

Protein binding partners of KCNJ4 in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads KCNJ4 as an antibody target. Whether an autoantibody or antibody against KCNJ4 could matter depends on whether native KCNJ4 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

KCNJ4 is annotated at the cell surface, where native KCNJ4 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 KCNJ4 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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