Seroatlas · Human Serome Atlas

FNDC3B

Fibronectin type III domain-containing protein 3B

Also known as: DKFZp762K137, FAD104, FLJ23399, FND3B_HUMAN, PRO4979, YVTM2421

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

Protein identityUniProt · HPA

UniProt accession: Q53EP0
Gene: FNDC3B
Ensembl: ENSG00000075420
Chromosome: 3
Canonical length: 1204 aa
Protein class: Predicted intracellular proteins, Predicted membrane proteins
Subcellular location: Endoplasmic reticulum

OverviewNCBI Gene

Enables RNA binding activity. Predicted to act upstream of or within several processes, including negative regulation of osteoblast differentiation; substrate adhesion-dependent cell spreading; and type II pneumocyte differentiation. Predicted to be located in endoplasmic reticulum. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

1204 residues, UniProt reviewed canonical sequence.

>Q53EP0|FNDC3B
     1  MYVTMMMTDQ IPLELPPLLN GEVAMMPHLV NGDAAQQVIL VQVNPGETFT IRAEDGTLQC
    61  IQGPAEVPMM SPNGSIPPIH VPPGYISQVI EDSTGVRRVV VTPQSPECYP PSYPSAMSPT
   121  HHLPPYLTHH PHFIHNSHTA YYPPVTGPGD MPPQFFPQHH LPHTIYGEQE IIPFYGMSTY
   181  ITREDQYSKP PHKKLKDRQI DRQNRLNSPP SSIYKSSCTT VYNGYGKGHS GGSGGGGSGS
   241  GPGIKKTERR ARSSPKSNDS DLQEYELEVK RVQDILSGIE KPQVSNIQAR AVVLSWAPPV
   301  GLSCGPHSGL SFPYSYEVAL SDKGRDGKYK IIYSGEELEC NLKDLRPATD YHVRVYAMYN
   361  SVKGSCSEPV SFTTHSCAPE CPFPPKLAHR SKSSLTLQWK APIDNGSKIT NYLLEWDEGK
   421  RNSGFRQCFF GSQKHCKLTK LCPAMGYTFR LAARNDIGTS GYSQEVVCYT LGNIPQMPSA
   481  PRLVRAGITW VTLQWSKPEG CSPEEVITYT LEIQEDENDN LFHPKYTGED LTCTVKNLKR
   541  STQYKFRLTA SNTEGKSCPS EVLVCTTSPD RPGPPTRPLV KGPVTSHGFS VKWDPPKDNG
   601  GSEILKYLLE ITDGNSEANQ WEVAYSGSAT EYTFTHLKPG TLYKLRACCI STGGHSQCSE
   661  SLPVRTLSIA PGQCRPPRVL GRPKHKEVHL EWDVPASESG CEVSEYSVEM TEPEDVASEV
   721  YHGPELECTV GNLLPGTVYR FRVRALNDGG YGPYSDVSEI TTAAGPPGQC KAPCISCTPD
   781  GCVLVGWESP DSSGADISEY RLEWGEDEES LELIYHGTDT RFEIRDLLPA AQYCCRLQAF
   841  NQAGAGPYSE LVLCQTPASA PDPVSTLCVL EEEPLDAYPD SPSACLVLNW EEPCNNGSEI
   901  LAYTIDLGDT SITVGNTTMH VMKDLLPETT YRIRIQAINE IGAGPFSQFI KAKTRPLPPL
   961  PPRLECAAAG PQSLKLKWGD SNSKTHAAED IVYTLQLEDR NKRFISIYRG PSHTYKVQRL
  1021  TEFTCYSFRI QAASEAGEGP FSETYTFSTT KSVPPTIKAP RVTQLEGNSC EILWETVPSM
  1081  KGDPVNYILQ VLVGRESEYK QVYKGEEATF QISGLQTNTD YRFRVCACRR CLDTSQELSG
  1141  AFSPSAAFVL QRSEVMLTGD MGSLDDPKMK SMMPTDEQFA AIIVLGFATL SILFAFILQY
  1201  FLMK

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against FNDC3B 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: 1
Mean surface accessibility (rSASA): 0.39
Highest tissue expression: 50 nTPM

Expression across tissuesHPA

Tissue

placenta: 50 nTPM
urinary bladder: 36 nTPM
bone marrow: 35 nTPM
adipose tissue: 32 nTPM
thyroid gland: 30 nTPM
ovary: 29 nTPM

Single-cell type

neutrophils: 6,467 nCPM
monocytes: 1,987 nCPM
plasma cells: 1,964 nCPM
endometrial glandular cells: 1,962 nCPM
neutrophil progenitors: 1,687 nCPM
urothelial cells: 1,609 nCPM

Immune cell

neutrophil: 38 nTPM
eosinophil: 21 nTPM
basophil: 14 nTPM
classical monocyte: 8.4 nTPM
intermediate monocyte: 5.3 nTPM
myeloid DC: 4.7 nTPM

Brain region

cerebral cortex: 93 nTPM
thalamus: 57 nTPM
choroid plexus: 54 nTPM
pons: 50 nTPM
hypothalamus: 46 nTPM
medulla oblongata: 36 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about FNDC3B.

Disease | ImmuneIEDB

Conditions an epitope on FNDC3B was assayed in.

chronic lymphocytic leukemia T cell

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): 0.04
gnomAD pLI: 1
gnomAD missense Z: 1.87
DepMap mean gene effect: -0.13
DepMap dependency class: selective

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

Molecular functions

RNA binding

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads FNDC3B as an antibody target. Whether an autoantibody or antibody against FNDC3B could matter depends on whether native FNDC3B is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

FNDC3B 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 FNDC3B as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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