Seroatlas · Human Serome Atlas

PIK3CA

Phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha isoform

Also known as: PI3K, PK3CA_HUMAN

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

Protein identityUniProt · HPA

UniProt accession
P42336
Gene
PIK3CA
Ensembl
ENSG00000121879
Chromosome
3
Canonical length
1068 aa
Protein class
Cancer-related genes, Disease related genes, Enzymes, FDA approved drug targets, Human disease related genes, Metabolic proteins, Predicted intracellular proteins, RAS pathway related proteins
Subcellular location
Microtubules,Primary cilium,Mitochondria,Cytosol

OverviewNCBI Gene

Phosphatidylinositol 3-kinase is composed of an 85 kDa regulatory subunit and a 110 kDa catalytic subunit. The protein encoded by this gene represents the catalytic subunit, which uses ATP to phosphorylate PtdIns, PtdIns4P and PtdIns(4,5)P2. This gene has been found to be oncogenic and has been implicated in cervical cancers. A pseudogene of this gene has been defined on chromosome 22. [provided by RefSeq, Apr 2016]

Canonical amino-acid sequenceUniProt

1068 residues, UniProt reviewed canonical sequence.

>P42336|PIK3CA
     1  MPPRPSSGEL WGIHLMPPRI LVECLLPNGM IVTLECLREA TLITIKHELF KEARKYPLHQ
    61  LLQDESSYIF VSVTQEAERE EFFDETRRLC DLRLFQPFLK VIEPVGNREE KILNREIGFA
   121  IGMPVCEFDM VKDPEVQDFR RNILNVCKEA VDLRDLNSPH SRAMYVYPPN VESSPELPKH
   181  IYNKLDKGQI IVVIWVIVSP NNDKQKYTLK INHDCVPEQV IAEAIRKKTR SMLLSSEQLK
   241  LCVLEYQGKY ILKVCGCDEY FLEKYPLSQY KYIRSCIMLG RMPNLMLMAK ESLYSQLPMD
   301  CFTMPSYSRR ISTATPYMNG ETSTKSLWVI NSALRIKILC ATYVNVNIRD IDKIYVRTGI
   361  YHGGEPLCDN VNTQRVPCSN PRWNEWLNYD IYIPDLPRAA RLCLSICSVK GRKGAKEEHC
   421  PLAWGNINLF DYTDTLVSGK MALNLWPVPH GLEDLLNPIG VTGSNPNKET PCLELEFDWF
   481  SSVVKFPDMS VIEEHANWSV SREAGFSYSH AGLSNRLARD NELRENDKEQ LKAISTRDPL
   541  SEITEQEKDF LWSHRHYCVT IPEILPKLLL SVKWNSRDEV AQMYCLVKDW PPIKPEQAME
   601  LLDCNYPDPM VRGFAVRCLE KYLTDDKLSQ YLIQLVQVLK YEQYLDNLLV RFLLKKALTN
   661  QRIGHFFFWH LKSEMHNKTV SQRFGLLLES YCRACGMYLK HLNRQVEAME KLINLTDILK
   721  QEKKDETQKV QMKFLVEQMR RPDFMDALQG FLSPLNPAHQ LGNLRLEECR IMSSAKRPLW
   781  LNWENPDIMS ELLFQNNEII FKNGDDLRQD MLTLQIIRIM ENIWQNQGLD LRMLPYGCLS
   841  IGDCVGLIEV VRNSHTIMQI QCKGGLKGAL QFNSHTLHQW LKDKNKGEIY DAAIDLFTRS
   901  CAGYCVATFI LGIGDRHNSN IMVKDDGQLF HIDFGHFLDH KKKKFGYKRE RVPFVLTQDF
   961  LIVISKGAQE CTKTREFERF QEMCYKAYLA IRQHANLFIN LFSMMLGSGM PELQSFDDIA
  1021  YIRKTLALDK TEQEALEYFM KQMNDAHHGG WTTKMDWIFH TIKQHALN

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against PIK3CA 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
0
Mean surface accessibility (rSASA)
0.23
Highest tissue expression
14 nTPM

Expression across tissuesHPA

Tissue

  • adipose tissue: 14 nTPM
  • thymus: 13 nTPM
  • tongue: 12 nTPM
  • bone marrow: 12 nTPM
  • retina: 12 nTPM
  • parathyroid gland: 11 nTPM

Single-cell type

  • neutrophils: 385 nCPM
  • neutrophil progenitors: 228 nCPM
  • mast cells: 204 nCPM
  • adipocytes: 172 nCPM
  • sertoli cells: 163 nCPM
  • adrenal cortex cells: 147 nCPM

Immune cell

  • neutrophil: 2.2 nTPM
  • naive B-cell: 1.6 nTPM
  • memory B-cell: 1.5 nTPM
  • basophil: 1.3 nTPM
  • classical monocyte: 1.3 nTPM
  • gdT-cell: 1.2 nTPM

Brain region

  • cerebellum: 33 nTPM
  • cerebral cortex: 29 nTPM
  • white matter: 25 nTPM
  • pons: 23 nTPM
  • medulla oblongata: 22 nTPM
  • midbrain: 21 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about PIK3CA.

Disease | AllUniProt

Conditions PIK3CA is implicated in, by any mechanism.

Disease | GeneticClinVar

112 pathogenic / likely-pathogenic of 1,601 ClinVar records.

Conditions with pathogenic or likely-pathogenic variants.

  • PIK3CA related overgrowth syndrome
  • Megalencephaly-capillary malformation-polymicrogyria syndrome
  • Neoplasm
  • Cowden syndrome
  • PIK3CA-related disorder

Disease | ImmuneIEDB

Conditions an epitope on PIK3CA was assayed in.

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)
0.12
gnomAD pLI
1
gnomAD missense Z
5.6
DepMap mean gene effect
-0.49
DepMap dependency class
selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 14% 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 PIK3CA 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 PIK3CA as an antibody target. Whether an autoantibody or antibody against PIK3CA could matter depends on whether native PIK3CA is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

PIK3CA is annotated at the cell surface, where native PIK3CA 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 PIK3CA as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/PIK3CA. 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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