Seroatlas · Human Serome Atlas

FAM20B

Glycosaminoglycan xylosylkinase

Also known as: GXK1, KIAA0475, XYLK_HUMAN

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

Protein identityUniProt · HPA

UniProt accession: O75063
Gene: FAM20B
Ensembl: ENSG00000116199
Chromosome: 1
Canonical length: 409 aa
Protein class: Metabolic proteins, Predicted intracellular proteins
Subcellular location: Nucleoplasm,Golgi apparatus

OverviewNCBI Gene

Enables phosphotransferase activity, alcohol group as acceptor. Predicted to be involved in proteoglycan biosynthetic process. Located in Golgi apparatus and nucleoplasm. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

409 residues, UniProt reviewed canonical sequence.

>O75063|FAM20B
     1  MKLKQRVVLL AILLVIFIFT KVFLIDNLDT SAANREDQRA FHRMMTGLRV ELAPKLDHTL
    61  QSPWEIAAQW VVPREVYPEE TPELGAVMHA MATKKIIKAD VGYKGTQLKA LLILEGGQKV
   121  VFKPKRYSRD HVVEGEPYAG YDRHNAEVAA FHLDRILGFH RAPLVVGRFV NLRTEIKPVA
   181  TEQLLSTFLT VGNNTCFYGK CYYCRETEPA CADGDIMEGS VTLWLPDVWP LQKHRHPWGR
   241  TYREGKLARW EYDESYCDAV KKTSPYDSGP RLLDIIDTAV FDYLIGNADR HHYESFQDDE
   301  GASMLILLDN AKSFGNPSLD ERSILAPLYQ CCIIRVSTWN RLNYLKNGVL KSALKSAMAH
   361  DPISPVLSDP HLDAVDQRLL SVLATVKQCT DQFGMDTVLV EDRMPLSHL

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against FAM20B 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: Other membrane
Secreted: No
Transmembrane segments: 1
Mean surface accessibility (rSASA): 0.26
Highest tissue expression: 28 nTPM

Expression across tissuesHPA

Tissue

blood vessel: 28 nTPM
retina: 27 nTPM
tongue: 24 nTPM
heart muscle: 22 nTPM
adrenal gland: 21 nTPM
colon: 21 nTPM

Single-cell type

podocytes: 85 nCPM
megakaryocyte-erythroid progenitors: 68 nCPM
urothelial cells: 66 nCPM
gonadotrophs: 63 nCPM
thyrotrophs: 62 nCPM
corticotrophs: 62 nCPM

Immune cell

NK-cell: 1.6 nTPM
naive B-cell: 1.5 nTPM
memory B-cell: 1.4 nTPM
gdT-cell: 1.3 nTPM
MAIT T-cell: 1.3 nTPM
plasmacytoid DC: 1.2 nTPM

Brain region

cerebral cortex: 39 nTPM
hypothalamus: 38 nTPM
basal ganglia: 37 nTPM
hippocampal formation: 35 nTPM
midbrain: 33 nTPM
pons: 33 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): 0.91
gnomAD pLI: 0
gnomAD missense Z: 0.98
DepMap mean gene effect: -0.08
DepMap dependency class: selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 13% 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

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads FAM20B as an antibody target. Whether an autoantibody or antibody against FAM20B could matter depends on whether native FAM20B is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

FAM20B 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 FAM20B as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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