Seroatlas · Human Serome Atlas

XAB2

Pre-mRNA-splicing factor SYF1

Also known as: HCNP, HCRN, NTC90, SYF1, SYF1_HUMAN

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

Protein identityUniProt · HPA

UniProt accession: Q9HCS7
Gene: XAB2
Ensembl: ENSG00000076924
Chromosome: 19
Canonical length: 855 aa
Protein class: Plasma proteins, Predicted intracellular proteins
Subcellular location: Nucleoplasm,Vesicles

OverviewNCBI Gene

Involved in DNA-templated transcription; mRNA splicing, via spliceosome; and transcription-coupled nucleotide-excision repair. Located in nucleoplasm. Part of U2-type catalytic step 2 spliceosome. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

855 residues, UniProt reviewed canonical sequence.

>Q9HCS7|XAB2
     1  MVVMARLSRP ERPDLVFEEE DLPYEEEIMR NQFSVKCWLR YIEFKQGAPK PRLNQLYERA
    61  LKLLPCSYKL WYRYLKARRA QVKHRCVTDP AYEDVNNCHE RAFVFMHKMP RLWLDYCQFL
   121  MDQGRVTHTR RTFDRALRAL PITQHSRIWP LYLRFLRSHP LPETAVRGYR RFLKLSPESA
   181  EEYIEYLKSS DRLDEAAQRL ATVVNDERFV SKAGKSNYQL WHELCDLISQ NPDKVQSLNV
   241  DAIIRGGLTR FTDQLGKLWC SLADYYIRSG HFEKARDVYE EAIRTVMTVR DFTQVFDSYA
   301  QFEESMIAAK METASELGRE EEDDVDLELR LARFEQLISR RPLLLNSVLL RQNPHHVHEW
   361  HKRVALHQGR PREIINTYTE AVQTVDPFKA TGKPHTLWVA FAKFYEDNGQ LDDARVILEK
   421  ATKVNFKQVD DLASVWCQCG ELELRHENYD EALRLLRKAT ALPARRAEYF DGSEPVQNRV
   481  YKSLKVWSML ADLEESLGTF QSTKAVYDRI LDLRIATPQI VINYAMFLEE HKYFEESFKA
   541  YERGISLFKW PNVSDIWSTY LTKFIARYGG RKLERARDLF EQALDGCPPK YAKTLYLLYA
   601  QLEEEWGLAR HAMAVYERAT RAVEPAQQYD MFNIYIKRAA EIYGVTHTRG IYQKAIEVLS
   661  DEHAREMCLR FADMECKLGE IDRARAIYSF CSQICDPRTT GAFWQTWKDF EVRHGNEDTI
   721  KEMLRIRRSV QATYNTQVNF MASQMLKVSG SATGTVSDLA PGQSGMDDMK LLEQRAEQLA
   781  AEAERDQPLR AQSKILFVRS DASREELAEL AQQVNPEEIQ LGEDEDEDEM DLEPNEVRLE
   841  QQSVPAAVFG SLKED

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against XAB2 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): 0.33
Highest tissue expression: 45 nTPM

Expression across tissuesHPA

Tissue

ovary: 45 nTPM
bone marrow: 42 nTPM
skin: 38 nTPM
testis: 36 nTPM
cervix: 35 nTPM
cerebellum: 35 nTPM

Single-cell type

breast lactating cells: 186 nCPM
epididymal principal cells: 175 nCPM
gastric chief cells: 149 nCPM
oocytes: 129 nCPM
breast hormone-responsive cells: 118 nCPM
lacrimal acinar cells: 97 nCPM

Immune cell

T-reg: 14 nTPM
non-classical monocyte: 14 nTPM
naive CD4 T-cell: 13 nTPM
naive B-cell: 12 nTPM
total PBMC: 12 nTPM
gdT-cell: 12 nTPM

Brain region

white matter: 40 nTPM
pons: 31 nTPM
medulla oblongata: 30 nTPM
basal ganglia: 30 nTPM
cerebellum: 29 nTPM
cerebral cortex: 29 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): 0.31
gnomAD pLI: 0.97
gnomAD missense Z: 1.94
DepMap mean gene effect: -2.11
DepMap dependency class: pan

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 5% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Cellular components

Protein domainsUniProt · Pfam · InterPro

HAT (Half-A-TPR) repeat
Tetratricopeptide-like helical domain superfamily
Tetratricopeptide repeat
Pre-mRNA-splicing factor Syf1-like
Pre-mRNA-splicing factor Syf1/CRNKL1-like, C-terminal HAT-repeats domain
Pre-mRNA-splicing factor Syf1/CRNKL1 C-terminal HAT repeat
Pre-mRNA-splicing factor Syf1-like, N-terminal HAT-repeats domain
Pre-mRNA-splicing factor SYF1, central HAT repeats domain
Pre-mRNA-splicing factor SYF1 middle HAT repeat
Pre-mRNA-splicing factor Syf1/CNRKL1 N-terminal HAT repeat

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of XAB2 in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads XAB2 as an antibody target. Whether an autoantibody or antibody against XAB2 could matter depends on whether native XAB2 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

XAB2 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 XAB2 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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