Seroatlas · Human Serome Atlas

XG

Glycoprotein Xg

Also known as: PBDX, XG_HUMAN

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

Protein identityUniProt · HPA

UniProt accession: P55808
Gene: XG
Ensembl: ENSG00000124343
Chromosome: X
Canonical length: 180 aa
Protein class: Blood group antigen proteins, Predicted membrane proteins

OverviewNCBI Gene

This gene encodes the XG blood group antigen, and is located at the pseudoautosomal boundary on the short (p) arm of chromosome X. The three 5' exons reside in the pseudoautosomal region and the remaining exons within the X-specific end. A truncated copy of this gene is found on the Y chromosome at the pseudoautosomal boundary. It is transcribed, but not expected to make a Y-chromosome specific gene product. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Nov 2008]

Canonical amino-acid sequenceUniProt

180 residues, UniProt reviewed canonical sequence.

>P55808|XG
     1  MESWWGLPCL AFLCFLMHAR GQRDFDLADA LDDPEPTKKP NSDIYPKPKP PYYPQPENPD
    61  SGGNIYPRPK PRPQPQPGNS GNSGGYFNDV DRDDGRYPPR PRPRPPAGGG GGGYSSYGNS
   121  DNTHGGDHHS TYGNPEGNMV AKIVSPIVSV VVVTLLGAAA SYFKLNNRRN CFRTHEPENV

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against XG 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: 1
Mean surface accessibility (rSASA): 0.66
Highest tissue expression: 34 nTPM

Expression across tissuesHPA

Tissue

skin: 34 nTPM
adipose tissue: 13 nTPM
blood vessel: 11 nTPM
vagina: 10 nTPM
esophagus: 9.7 nTPM
cervix: 9.4 nTPM

Single-cell type

esophageal apical cells: 253 nCPM
thymocytes: 160 nCPM
suprabasal keratinocytes: 98 nCPM
fibro-adipogenic progenitors: 83 nCPM
esophageal suprabasal cells: 61 nCPM
basal keratinocytes: 43 nCPM

Immune cell

memory B-cell: 0.3 nTPM
naive B-cell: 0.1 nTPM
basophil: 0 nTPM
classical monocyte: 0 nTPM
eosinophil: 0 nTPM
gdT-cell: 0 nTPM

Brain region

white matter: 1.3 nTPM
spinal cord: 0.8 nTPM
medulla oblongata: 0.7 nTPM
midbrain: 0.4 nTPM
pons: 0.4 nTPM
cerebellum: 0.2 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): 1.66
gnomAD pLI: 0
gnomAD missense Z: -0.03
DepMap mean gene effect: 0.08
DepMap dependency class: none

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 3% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Cellular components

plasma membrane

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

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

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

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