Seroatlas · Human Serome Atlas

PPP4R3B

Serine/threonine-protein phosphatase 4 regulatory subunit 3B

Also known as: FLFL2, FLJ31474, KIAA1387, P4R3B_HUMAN, PSY2, SMEK2

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

Protein identityUniProt · HPA

UniProt accession: Q5MIZ7
Gene: PPP4R3B
Ensembl: ENSG00000275052
Chromosome: 2
Canonical length: 849 aa
Protein class: Predicted intracellular proteins
Subcellular location: Nucleoplasm,Nuclear speckles,Centrosome

OverviewNCBI Gene

Predicted to enable protein phosphatase activator activity. Involved in regulation of double-strand break repair. Located in centrosome; chromatin; and nuclear speck. Part of protein phosphatase 4 complex. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

849 residues, UniProt reviewed canonical sequence.

>Q5MIZ7|PPP4R3B
     1  MSDTRRRVKV YTLNEDRQWD DRGTGHVSST YVEELKGMSL LVRAESDGSL LLESKINPNT
    61  AYQKQQDTLI VWSEAENYDL ALSFQEKAGC DEIWEKICQV QGKDPSVEVT QDLIDESEEE
   121  RFEEMPETSH LIDLPTCELN KLEEIADLVT SVLSSPIRRE KLALALENEG YIKKLLQLFQ
   181  ACENLENTEG LHHLYEIIRG ILFLNKATLF EVMFSDECIM DVVGCLEYDP ALAQPKRHRE
   241  FLTKTAKFKE VIPITDSELR QKIHQTYRVQ YIQDIILPTP SVFEENFLST LTSFIFFNKV
   301  EIVSMLQEDE KFLSEVFAQL TDEATDDDKR RELVNFFKEF CAFSQTLQPQ NRDAFFKTLA
   361  KLGILPALEI VMGMDDLQVR SAATDIFSYL VEFSPSMVRE FVMQEAQQSD DDILLINVVI
   421  EQMICDTDPE LGGAVQLMGL LRTLIDPENM LATTNKTEKS EFLNFFYNHC MHVLTAPLLT
   481  NTSEDKCEKD FFLKHYRYSW SFICTPSHSH SHSTPSSSIS QDNIVGSNKN NTICPDNYQT
   541  AQLLALILEL LTFCVEHHTY HIKNYIMNKD LLRRVLVLMN SKHTFLALCA LRFMRRIIGL
   601  KDEFYNRYIT KGNLFEPVIN ALLDNGTRYN LLNSAVIELF EFIRVEDIKS LTAHIVENFY
   661  KALESIEYVQ TFKGLKTKYE QEKDRQNQKL NSVPSILRSN RFRRDAKALE EDEEMWFNED
   721  EEEEGKAVVA PVEKPKPEDD FPDNYEKFME TKKAKESEDK ENLPKRTSPG GFKFTFSHSA
   781  SAANGTNSKS VVAQIPPATS NGSSSKTTNL PTSVTATKGS LVGLVDYPDD EEEDEEEESS
   841  PRKRPRLGS

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against PPP4R3B 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): 0.36
Highest tissue expression: 45 nTPM

Expression across tissuesHPA

Tissue

liver: 45 nTPM
thymus: 39 nTPM
tonsil: 36 nTPM
lymph node: 36 nTPM
retina: 33 nTPM
kidney: 31 nTPM

Single-cell type

neutrophil progenitors: 213 nCPM
respiratory ciliated cells: 208 nCPM
neutrophils: 206 nCPM
fallopian tube ciliated cells: 178 nCPM
endometrial ciliated cells: 158 nCPM
myonuclei: 155 nCPM

Immune cell

eosinophil: 27 nTPM
basophil: 26 nTPM
naive CD4 T-cell: 25 nTPM
T-reg: 24 nTPM
total PBMC: 24 nTPM
MAIT T-cell: 23 nTPM

Brain region

cerebellum: 43 nTPM
choroid plexus: 42 nTPM
white matter: 38 nTPM
hypothalamus: 36 nTPM
midbrain: 35 nTPM
medulla oblongata: 34 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): 0.37
gnomAD pLI: 0.71
DepMap mean gene effect: -0.08
DepMap dependency class: selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 7% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Molecular functions

protein phosphatase activator activity

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of PPP4R3B in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

PPP4C

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads PPP4R3B as an antibody target. Whether an autoantibody or antibody against PPP4R3B could matter depends on whether native PPP4R3B is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

PPP4R3B 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 PPP4R3B as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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