Seroatlas · Human Serome Atlas

PIK3R4

Phosphoinositide 3-kinase regulatory subunit 4

Also known as: p150, PI3R4_HUMAN, VPS15

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

Protein identityUniProt · HPA

UniProt accession
Q99570
Gene
PIK3R4
Ensembl
ENSG00000196455
Chromosome
3
Canonical length
1358 aa
Protein class
Enzymes, Predicted intracellular proteins
Subcellular location
Vesicles,Microtubules,Cytokinetic bridge,Primary cilium,Basal body

OverviewNCBI Gene

Predicted to enable protein serine/threonine kinase activity. Involved in several processes, including early endosome to late endosome transport; phosphatidylinositol 3-kinase/protein kinase B signal transduction; and phosphatidylinositol-3-phosphate biosynthetic process. Located in ciliary basal body; intercellular bridge; and late endosome. Part of phosphatidylinositol 3-kinase complex, class III. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

1358 residues, UniProt reviewed canonical sequence.

>Q99570|PIK3R4
     1  MGNQLAGIAP SQILSVESYF SDIHDFEYDK SLGSTRFFKV ARAKHREGLV VVKVFAIQDP
    61  TLPLTSYKQE LEELKIRLNS AQNCLPFQKA SEKASEKAAM LFRQYVRDNL YDRISTRPFL
   121  NNIEKRWIAF QILTAVDQAH KSGVRHGDIK TENVMVTSWN WVLLTDFASF KPTYLPEDNP
   181  ADFNYFFDTS RRRTCYIAPE RFVDGGMFAT ELEYMRDPST PLVDLNSNQR TRGELKRAMD
   241  IFSAGCVIAE LFTEGVPLFD LSQLLAYRNG HFFPEQVLNK IEDHSIRELV TQMIHREPDK
   301  RLEAEDYLKQ QRGNAFPEIF YTFLQPYMAQ FAKETFLSAD ERILVIRKDL GNIIHNLCGH
   361  DLPEKAEGEP KENGLVILVS VITSCLQTLK YCDSKLAALE LILHLAPRLS VEILLDRITP
   421  YLLHFSNDSV PRVRAEALRT LTKVLALVKE VPRNDINIYP EYILPGIAHL AQDDATIVRL
   481  AYAENIALLA ETALRFLELV QLKNLNMEND PNNEEIDEVT HPNGNYDTEL QALHEMVQQK
   541  VVTLLSDPEN IVKQTLMENG ITRLCVFFGR QKANDVLLSH MITFLNDKND WHLRGAFFDS
   601  IVGVAAYVGW QSSSILKPLL QQGLSDAEEF VIVKALYALT CMCQLGLLQK PHVYEFASDI
   661  APFLCHPNLW IRYGAVGFIT VVARQISTAD VYCKLMPYLD PYITQPIIQI ERKLVLLSVL
   721  KEPVSRSIFD YALRSKDITS LFRHLHMRQK KRNGSLPDCP PPEDPAIAQL LKKLLSQGMT
   781  EEEEDKLLAL KDFMMKSNKA KANIVDQSHL HDSSQKGVID LAALGITGRQ VDLVKTKQEP
   841  DDKRARKHVK QDSNVNEEWK SMFGSLDPPN MPQALPKGSD QEVIQTGKPP RSESSAGICV
   901  PLSTSSQVPE VTTVQNKKPV IPVLSSTILP STYQIRITTC KTELQQLIQQ KREQCNAERI
   961  AKQMMENAEW ESKPPPPGWR PKGLLVAHLH EHKSAVNRIR VSDEHSLFAT CSNDGTVKIW
  1021  NSQKMEGKTT TTRSILTYSR IGGRVKTLTF CQGSHYLAIA SDNGAVQLLG IEASKLPKSP
  1081  KIHPLQSRIL DQKEDGCVVD MHHFNSGAQS VLAYATVNGS LVGWDLRSSS NAWTLKHDLK
  1141  SGLITSFAVD IHQCWLCIGT SSGTMACWDM RFQLPISSHC HPSRARIRRL SMHPLYQSWV
  1201  IAAVQGNNEV SMWDMETGDR RFTLWASSAP PLSELQPSPH SVHGIYCSPA DGNPILLTAG
  1261  SDMKIRFWDL AYPERSYVVA GSTSSPSVSY YRKIIEGTEV VQEIQNKQKV GPSDDTPRRG
  1321  PESLPVGHHD IITDVATFQT TQGFIVTASR DGIVKVWK

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against PIK3R4 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
Intracellular
Secreted
No
Transmembrane segments
0
Mean surface accessibility (rSASA)
0.31
Highest tissue expression
20 nTPM

Expression across tissuesHPA

Tissue

  • liver: 20 nTPM
  • parathyroid gland: 17 nTPM
  • retina: 15 nTPM
  • thyroid gland: 12 nTPM
  • testis: 11 nTPM
  • thymus: 11 nTPM

Single-cell type

  • cone photoreceptor cells: 75 nCPM
  • rod photoreceptor cells: 67 nCPM
  • erythrocyte progenitors: 63 nCPM
  • lactotrophs: 62 nCPM
  • cardiomyocytes: 60 nCPM
  • neutrophils: 56 nCPM

Immune cell

  • basophil: 9.7 nTPM
  • MAIT T-cell: 9.3 nTPM
  • NK-cell: 8.5 nTPM
  • eosinophil: 7 nTPM
  • myeloid DC: 6.9 nTPM
  • T-reg: 6.8 nTPM

Brain region

  • white matter: 28 nTPM
  • choroid plexus: 26 nTPM
  • cerebellum: 25 nTPM
  • cerebral cortex: 23 nTPM
  • hypothalamus: 23 nTPM
  • basal ganglia: 22 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)
0.39
gnomAD pLI
0.02
gnomAD missense Z
2.48
DepMap mean gene effect
-0.46
DepMap dependency class
selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 11% 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 PIK3R4 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 PIK3R4 as an antibody target. Whether an autoantibody or antibody against PIK3R4 could matter depends on whether native PIK3R4 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

PIK3R4 is annotated as predominantly intracellular. Intracellular proteins are common autoantibody markers, becoming visible to the immune system after cell injury or altered processing, but are usually markers of disease rather than direct drivers.

Annotation status

The present source text does not explicitly label PIK3R4 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/PIK3R4. 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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