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Symbol XAF1 contributors: mct - updated : 28-03-2020
HGNC name XIAP associated factor 1
HGNC id 30932
Location 17p13.1      Physical location : 6.659.155 - 6.678.962
Synonym name
  • X-linked inhibitor of apoptosis (XIAP)-associated factor 1
  • BIRC4-binding protein
  • Synonym symbol(s) HSXIAPAF1, XIAPAF1, BIRC4BP
    TYPE functioning gene
    STRUCTURE 20.24 kb     7 Exon(s)
    MAPPING cloned Y linked N status provisional
    Map cen - D17S926 - D17S2169 - D17S2167 - [D17S1828 - D17S1832 ] - D17S796 - D17S1881 - D17S786 - cen
    Authors Fong (00)
    Text [XIAPAF1 ]
    regionally located telomeric to TP53
    TRANSCRIPTS type messenger
    identificationnb exonstypebpproduct
    ProteinkDaAAspecific expressionYearPubmed
    6 - 3360 - 282 widely, low expression in any cancer cell lines 2018 30042418
  • variant 2, or XAF1B
  • lacks exon 3
  • 7 - 3417 - 301 widely, not expressed in cancer cell lines 2018 30042418
    variant 1, or XAF1A
    7 splicing - - - expressed in a gastric cancer cell line MKN45P, and also pancreatic, colorectal, and breast cancer cells 2015 25216542
  • variant lacked exon 5 and possessed a unique exon 3 that contained exon 3-ext derived from the intronic region, resulting in seven exons
  • upregulated in the peripheral blood of gastric cancer patients
  • - splicing - - 164 . in a variety of cancer cell lines and also in normal tissues 2006 16343440
  • containing a cryptic exon (exon 4b) that into the mRNA introduces an in-frame stop codon
  • lacking the C-terminal domain of the previously described XAF1(A), but containing a unique 24 AA carboxy terminus
  • 7 - 3626 - 301 - 2018 30042418
    7 - 3823 - 241 - 2018 30042418
    8 - 3573 - 172 - 2018 30042418
    8 - 3569 - 204 - 2018 30042418
    6 - 3331 - 250 - 2018 30042418
    7 - 3512 - 204 - 2018 30042418
    5 - 3274 - 231 - 2018 30042418
    Type widely
       expressed in (based on citations)
    SystemOrgan level 1Organ level 2Organ level 3Organ level 4LevelPubmedSpeciesStageRna symbol
    Digestiveesophagus   highly
    Lymphoid/Immunespleen   highly
    Reproductivefemale systemuterus   
     male systemtestis   
    Urinarykidney   highly Homo sapiens
    cell lineage
    cell lines
    at STAGE
  • six zinc finger motifs at its N-terminus, a highly compact N-terminal domain (XAF1(NTD)
  • a middle domain (XAF1(MD)
  • TRAF type zinc finger, required for self-association or interaction with other proteins
  • a 42-residue unstructured linker
  • C-terminal portion critical for its pro-apoptotic function, XAF1(CTD), C-terminal XAF1 fragment harboring XAF1(RBD) was found to be substantially ubiquitinated by XIAP(RING)
    intraspecies homolog to FLN29,TRAF3
    CATEGORY transcription factor , tumor suppressor
    SUBCELLULAR LOCALIZATION     intracellular
    basic FUNCTION
  • regulation of apoptosis (loss of XAF1 important for malignant cell survival)
  • antagonizing the anticaspase activity of XIAP and may be important in mediating apoptosis resistance in cancer cells
  • plays a critical role in interferon-induced sensitization to TNF-related apoptosis-inducing ligand
  • mediates apoptosis induced by the ERK1/2 pathway in colon cancer (Yu 2007)
  • role of XAF1 in promoting apoptosis in vascular endothelial cells after DENV2 infection
  • novel role for XAF1 in TP53 stress response, adding a new layer of complexity to the mechanisms by which TP53 determines cell-fate decisions
  • XAF1 forms a positive feedback loop with IRF1 to drive apoptotic stress response and suppress tumorigenesis
  • both YY1 and XAF1 have key roles in prostate cancer (PCa) progression and are associated with worse clinical outcomes
  • pro&
  • 8209;apoptotic tumor suppressor that frequently displays epigenetic inactivation in various types of human malignancies, including colorectal cancer
    CELLULAR PROCESS cell life, cell death/apoptosis
    a component
  • complexing with XIAP to regulate motoneuron resistance to apoptotic cell death
    small molecule
  • inhibiting the function of CASP3, CASP7 and CASP9 key effector proteases of apoptosis
  • XAF1 binds directly to the N-terminal proline-rich domain of TP53 and thus interferes with E3 ubiquitin ligase MDM2 binding and ubiquitination of TP53
  • binds to XIAP and blocks its anti-apoptotic activity
  • XAF1 is likely a downstream target of KIF1B beta
  • XAF1 interacts with TRAF2 and inhibits TRAF2-dependent NFKB1 activation, in part, by blocking TRAF2 polyubiquitination
  • XAF1 acts as a feedback regulator of the TNF receptor signaling pathway to suppress NFKB1 activation
  • macrophages activated by metabolic endotoxemia infiltrated into islets and produced IFNB1, which induced beta-cell apoptosis by increasing the expression of XAF1
  • functions as a transcriptional coactivator of IRF1 to suppress tumorigenesis
  • YY1 is able to mediate XAF1 silencing
  • SARM1 deficiency exacerbates the progression of prion pathogenesis, by up-regulating XAF1, which promotes neuronal apoptosis, and accelerates prion disease
  • TGFB1 protects colon tumor cells from apoptosis through XAF1 suppression
  • cell & other
    activated by IFNA,IFNB
    repressed by TGFB1 (TGFB1 represses XAF1 transcription through Erk activation, thereby protecting tumor cells from apoptotic stresses)
    Other induced expression in cancer cell lines, with high levels of XIAP
    corresponding disease(s)
    Other morbid association(s)
    TypeGene ModificationChromosome rearrangementProtein expressionProtein Function
    tumoral     --low  
    low expressed by aberrant promoter methylation in gastric adenocarcinoma in progression
    by hypermethylation in prostate, kidney and bladder carcinoma, in malignant progression
    tumoral     --over  
    significantly reduced invasion and migration of SKOV3 cells (ovarian cancer), and inhibited vascular endothelial growth factor protein expression
    tumoral     --over  
    impairs neuroblastoma tumor progression
    tumoral     --low  
    implicated in clear-cell renal cancer progression
    Variant & Polymorphism
    Candidate gene
  • prognostic marker in pancreatic cancer
  • Therapy target
    XAF1 might constitute a therapeutic target in prion disease
    XAF1 may be a candidate tumor suppressor in neuroblastoma
    could be a potential candidate for pancreatic cancer gene therapy