Seroatlas · Human Serome Atlas

KCNMB3

Calcium-activated potassium channel subunit beta-3

Also known as: KCMB3_HUMAN, KCNMB2, KCNMBL

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

Protein identityUniProt · HPA

UniProt accession
Q9NPA1
Gene
KCNMB3
Ensembl
ENSG00000171121
Chromosome
3
Canonical length
279 aa
Protein class
FDA approved drug targets, Predicted intracellular proteins, Predicted membrane proteins, Transporters
Subcellular location
Nucleoplasm,Mitochondria

OverviewNCBI Gene

MaxiK channels are large conductance, voltage and calcium-sensitive potassium channels which are fundamental to the control of smooth muscle tone and neuronal excitability. MaxiK channels can be formed by 2 subunits: the pore-forming alpha subunit and the modulatory beta subunit. The protein encoded by this gene is an auxiliary beta subunit which may partially inactivate or slightly decrease the activation time of MaxiK alpha subunit currents. Alternative splicing results in multiple transcript variants. A related pseudogene has been identified on chromosome 22. [provided by RefSeq, Jul 2009]

Canonical amino-acid sequenceUniProt

279 residues, UniProt reviewed canonical sequence.

>Q9NPA1|KCNMB3
     1  MDFSPSSELG FHFVAFILLT RHRTAFPASG KKRETDYSDG DPLDVHKRLP SSAGEDRAVM
    61  LGFAMMGFSV LMFFLLGTTI LKPFMLSIQR EESTCTAIHT DIMDDWLDCA FTCGVHCHGQ
   121  GKYPCLQVFV NLSHPGQKAL LHYNEEAVQI NPKCFYTPKC HQDRNDLLNS ALDIKEFFDH
   181  KNGTPFSCFY SPASQSEDVI LIKKYDQMAI FHCLFWPSLT LLGGALIVGM VRLTQHLSLL
   241  CEKYSTVVRD EVGGKVPYIE QHQFKLCIMR RSKGRAEKS

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against KCNMB3 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)
0.4
Highest tissue expression
8.4 nTPM

Expression across tissuesHPA

Tissue

  • spleen: 8.4 nTPM
  • cerebellum: 7.8 nTPM
  • cerebral cortex: 6.7 nTPM
  • liver: 6.3 nTPM
  • pancreas: 6.1 nTPM
  • hippocampal formation: 5.6 nTPM

Single-cell type

  • podocytes: 31 nCPM
  • late spermatids: 27 nCPM
  • cardiomyocytes: 19 nCPM
  • epicardial cells: 18 nCPM
  • renal collecting duct intercalated cells: 18 nCPM
  • renal collecting duct principal cells: 16 nCPM

Immune cell

  • memory B-cell: 1.2 nTPM
  • NK-cell: 1.1 nTPM
  • basophil: 0.8 nTPM
  • naive B-cell: 0.7 nTPM
  • neutrophil: 0.6 nTPM
  • gdT-cell: 0.4 nTPM

Brain region

  • medulla oblongata: 4.6 nTPM
  • cerebral cortex: 4.4 nTPM
  • basal ganglia: 4.2 nTPM
  • pons: 4.2 nTPM
  • thalamus: 4.2 nTPM
  • choroid plexus: 4.1 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)
1.87
gnomAD pLI
0
gnomAD missense Z
0.84
DepMap mean gene effect
0.09
DepMap dependency class
none

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 9% 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 KCNMB3 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 KCNMB3 as an antibody target. Whether an autoantibody or antibody against KCNMB3 could matter depends on whether native KCNMB3 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

KCNMB3 is annotated at the cell surface, where native KCNMB3 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 KCNMB3 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/KCNMB3. 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).

© 2026 · Seroatlas, Discover Oregon LLC · Terms of use

Loading the interactive Seroatlas protein explorer...