Seroatlas · Human Serome Atlas

ST8SIA3

Alpha-N-acetylneuraminate alpha-2,8-sialyltransferase ST8SIA3

Also known as: SIA8C_HUMAN, SIAT8C

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

Protein identityUniProt · HPA

UniProt accession: O43173
Gene: ST8SIA3
Ensembl: ENSG00000177511
Chromosome: 18
Canonical length: 380 aa
Protein class: Predicted intracellular proteins, Predicted membrane proteins
Subcellular location: Golgi apparatus
Quaternary structure: Homodimer

OverviewNCBI Gene

Enables alpha-N-acetylneuraminate alpha-2,8-sialyltransferase activity and identical protein binding activity. Involved in several processes, including ganglioside biosynthetic process; glycoprotein metabolic process; and sialylation. Predicted to be located in Golgi membrane. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

380 residues, UniProt reviewed canonical sequence.

>O43173|ST8SIA3
     1  MRNCKMARVA SVLGLVMLSV ALLILSLISY VSLKKENIFT TPKYASPGAP RMYMFHAGFR
    61  SQFALKFLDP SFVPITNSLT QELQEKPSKW KFNRTAFLHQ RQEILQHVDV IKNFSLTKNS
   121  VRIGQLMHYD YSSHKYVFSI SNNFRSLLPD VSPIMNKHYN ICAVVGNSGI LTGSQCGQEI
   181  DKSDFVFRCN FAPTEAFQRD VGRKTNLTTF NPSILEKYYN NLLTIQDRNN FFLSLKKLDG
   241  AILWIPAFFF HTSATVTRTL VDFFVEHRGQ LKVQLAWPGN IMQHVNRYWK NKHLSPKRLS
   301  TGILMYTLAS AICEEIHLYG FWPFGFDPNT REDLPYHYYD KKGTKFTTKW QESHQLPAEF
   361  QLLYRMHGEG LTKLTLSHCA

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against ST8SIA3 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): 0.32
Highest tissue expression: 24 nTPM

Expression across tissuesHPA

Tissue

basal ganglia: 24 nTPM
cerebral cortex: 21 nTPM
cerebellum: 17 nTPM
hypothalamus: 11 nTPM
pituitary gland: 9 nTPM
hippocampal formation: 8.7 nTPM

Single-cell type

brain inhibitory neurons: 111 nCPM
corticotrophs: 100 nCPM
brain excitatory neurons: 71 nCPM
retinal horizontal cells: 68 nCPM
thyrotrophs: 64 nCPM
pancreatic islet cells: 60 nCPM

Immune cell

basophil: 0 nTPM
classical monocyte: 0 nTPM
eosinophil: 0 nTPM
gdT-cell: 0 nTPM
intermediate monocyte: 0 nTPM
MAIT T-cell: 0 nTPM

Brain region

basal ganglia: 76 nTPM
cerebral cortex: 67 nTPM
hypothalamus: 67 nTPM
hippocampal formation: 50 nTPM
cerebellum: 45 nTPM
white matter: 45 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): 0.41
gnomAD pLI: 0.86
gnomAD missense Z: 1.47
DepMap mean gene effect: -0.04
DepMap dependency class: selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 2% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Molecular functions

Cellular components

Golgi membrane

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads ST8SIA3 as an antibody target. Whether an autoantibody or antibody against ST8SIA3 could matter depends on whether native ST8SIA3 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

ST8SIA3 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 ST8SIA3 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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