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PAXX PAXX non-homologous end joining factor [ Homo sapiens (human) ]

Gene ID: 286257, updated on 12-Apr-2026
Official Symbol
PAXXprovided by HGNC
Official Full Name
PAXX non-homologous end joining factorprovided by HGNC
Primary source
HGNC:HGNC:27849
See related
Ensembl:ENSG00000310560 MIM:616315; AllianceGenome:HGNC:27849
Gene type
protein coding
RefSeq status
REVIEWED
Organism
Homo sapiens
Lineage
Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo
Also known as
XLS; C9orf142
Summary
The protein encoded by this gene plays a role in the nonhomologous end joining (NHEJ) pathway of DNA double-strand break repair. The encoded protein may function to stabilize the Ku70/Ku80 heterodimer to facilitate the assembly and maintain the stability of the NHEJ complex. [provided by RefSeq, Jul 2016]
Expression
Ubiquitous expression in spleen (RPKM 25.7), lymph node (RPKM 14.9) and 25 other tissues See more
Orthologs
all
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Try the new Transcripts and proteins table
See PAXX in Genome Data Viewer
Location:
9q34.3
Exon count:
7
Annotation release Status Assembly Chr Location
RS_2025_08 current GRCh38.p14 (GCF_000001405.40) 9 NC_000009.12 (136992422..136993976)
RS_2025_08 current T2T-CHM13v2.0 (GCF_009914755.1) 9 NC_060933.1 (149226833..149228387)
RS_2024_09 previous assembly GRCh37.p13 (GCF_000001405.25) 9 NC_000009.11 (139886874..139888428)

Chromosome 9 - NC_000009.12Genomic Context describing neighboring genes Neighboring gene H3K27ac-H3K4me1 hESC enhancer GRCh37_chr9:139873016-139873995 Neighboring gene prostaglandin D2 synthase Neighboring gene H3K27ac-H3K4me1 hESC enhancer GRCh37_chr9:139878783-139879340 Neighboring gene H3K27ac-H3K4me1 hESC enhancer GRCh37_chr9:139879341-139879896 Neighboring gene lipocalin like 1 Neighboring gene Sharpr-MPRA regulatory region 3127 Neighboring gene ATAC-STARR-seq lymphoblastoid silent region 20564 Neighboring gene ATAC-STARR-seq lymphoblastoid silent region 20565 Neighboring gene H3K4me1 hESC enhancer GRCh37_chr9:139887067-139887609 Neighboring gene ATAC-STARR-seq lymphoblastoid active region 29337 Neighboring gene CLIC family member 3 Neighboring gene CDK7 strongly-dependent group 2 enhancer GRCh37_chr9:139904888-139906087 Neighboring gene ATP binding cassette subfamily A member 2 Neighboring gene H3K27ac-H3K4me1 hESC enhancer GRCh37_chr9:139917045-139917624 Neighboring gene H3K4me1 hESC enhancer GRCh37_chr9:139922830-139923574 Neighboring gene long intergenic non-protein coding RNA 2908

Go to nucleotide: Graphics FASTA GenBank

  • Project title: Tissue-specific circular RNA induction during human fetal development
  • Description: 35 human fetal samples from 6 tissues (3 - 7 replicates per tissue) collected between 10 and 20 weeks gestational time were sequenced using Illumina TruSeq Stranded Total RNA
  • BioProject: PRJNA270632
  • Publication: PMID 26076956
  • Analysis date: Mon Apr 2 22:54:59 2018

Related articles in PubMed

  1. PAXX Participates in Base Excision Repair via Interacting with Pol β and Contributes to TMZ Resistance in Glioma Cells. Yang B, et al. J Mol Neurosci, 2018 Oct. PMID 30238427, Free PMC Article
  2. Interactome analysis identifies a new paralogue of XRCC4 in non-homologous end joining DNA repair pathway. Xing M, et al. Nat Commun, 2015 Feb 11. PMID 25670504, Free PMC Article
  3. PAXX binding to the NHEJ machinery explains functional redundancy with XLF. Seif-El-Dahan M, et al. Sci Adv, 2023 Jun 2. PMID 37256950, Free PMC Article
  4. PAXX Is an Accessory c-NHEJ Factor that Associates with Ku70 and Has Overlapping Functions with XLF. Tadi SK, et al. Cell Rep, 2016 Oct 4. PMID 27705800
  5. Absence of XRCC4 and its paralogs in human cells reveal differences in outcomes for DNA repair and V(D)J recombination. Ruis B, et al. DNA Repair (Amst), 2020 Jan. PMID 31731258, Free PMC Article

See all (35) citations in PubMed

GeneRIFs: Gene References Into Functions

What's a GeneRIF?
  1. PAXX binding to the NHEJ machinery explains functional redundancy with XLF.
    Title: PAXX binding to the NHEJ machinery explains functional redundancy with XLF.
  2. Absence of XRCC4 and its paralogs in human cells reveal differences in outcomes for DNA repair and V(D)J recombination.
    Title: Absence of XRCC4 and its paralogs in human cells reveal differences in outcomes for DNA repair and V(D)J recombination.
  3. Synthetic lethality between DNA repair factors Xlf and Paxx is rescued by inactivation of Trp53
    Title: Synthetic lethality between DNA repair factors Xlf and Paxx is rescued by inactivation of Trp53.
  4. PAXX, XLF and XRCC4 synergise in the efficient DNA double-strand breaks recruitment, substrate recognition and stimulation of Pol lambda enzymatic activity during nonhomologous end joining DNA repair.
    Title: PAXX and its paralogs synergistically direct DNA polymerase λ activity in DNA repair.
  5. PAXX contributes to base excision repair pathway via interaction of polymerase beta. PAXX deficiency causes TMZ sensitivity.
    Title: PAXX Participates in Base Excision Repair via Interacting with Pol β and Contributes to TMZ Resistance in Glioma Cells.
  6. Although PAXX-deficient cells lack c-NHEJ phenotypes, PAXX forms a stable ternary complex with Ku bound to DNA. Thus, PAXX plays an accessory role during c-NHEJ that is largely overlapped by XLF's function.
    Title: PAXX Is an Accessory c-NHEJ Factor that Associates with Ku70 and Has Overlapping Functions with XLF.
  7. These data identify PAXX as a new Non-homologous end joining factor.
    Title: Interactome analysis identifies a new paralogue of XRCC4 in non-homologous end joining DNA repair pathway.
  8. PAXX promotes Ku-dependent DNA ligation in vitro and assembly of core nonhomologous end-joining (NHEJ) factors on damaged chromatin in cells. These findings identify PAXX as a new component of the NHEJ machinery.
    Title: DNA repair. PAXX, a paralog of XRCC4 and XLF, interacts with Ku to promote DNA double-strand break repair.
Submit: New GeneRIF Correction

Review eQTL and phenotype association data in this region using PheGenI

See variants in ClinVar

See studies and variants in dbVar

See Variation Viewer (GRCh37.p13)

Products Interactant Other Gene Complex Source Pubs Description

Markers

Homology

Gene Ontology Provided by GOA

Function Evidence Code Pubs
enables DNA polymerase binding IPI
Inferred from Physical Interaction
more info
 PubMed 
enables identical protein binding IPI
Inferred from Physical Interaction
more info
 PubMed 
enables molecular adaptor activity IBA
Inferred from Biological aspect of Ancestor
more info
  
enables molecular adaptor activity IDA
Inferred from Direct Assay
more info
 PubMed 
enables protein binding IPI
Inferred from Physical Interaction
more info
 PubMed 
enables protein homodimerization activity IDA
Inferred from Direct Assay
more info
 PubMed 
Process Evidence Code Pubs
involved_in DNA damage response IDA
Inferred from Direct Assay
more info
 PubMed 
involved_in double-strand break repair via nonhomologous end joining IBA
Inferred from Biological aspect of Ancestor
more info
  
involved_in double-strand break repair via nonhomologous end joining IDA
Inferred from Direct Assay
more info
 PubMed 
involved_in double-strand break repair via nonhomologous end joining IEA
Inferred from Electronic Annotation
more info
  
involved_in double-strand break repair via nonhomologous end joining IMP
Inferred from Mutant Phenotype
more info
 PubMed 
Component Evidence Code Pubs
part_of Ku70:Ku80 complex IDA
Inferred from Direct Assay
more info
 PubMed 
located_in chromosome IEA
Inferred from Electronic Annotation
more info
  
located_in cytoplasm IEA
Inferred from Electronic Annotation
more info
  
part_of nonhomologous end joining complex IBA
Inferred from Biological aspect of Ancestor
more info
  
part_of nonhomologous end joining complex IDA
Inferred from Direct Assay
more info
 PubMed 
located_in nucleoplasm IDA
Inferred from Direct Assay
more info
  
is_active_in nucleus IBA
Inferred from Biological aspect of Ancestor
more info
  
located_in nucleus IDA
Inferred from Direct Assay
more info
 PubMed 
located_in nucleus IEA
Inferred from Electronic Annotation
more info
  
is_active_in site of double-strand break IBA
Inferred from Biological aspect of Ancestor
more info
  
located_in site of double-strand break IDA
Inferred from Direct Assay
more info
 PubMed 
Preferred Names
protein PAXX
Names
XRCC4-like small protein
paralog of XRCC4 and XLF

NEW Try the new Transcript table

RefSeqs maintained independently of Annotated Genomes

These reference sequences exist independently of genome builds. Explain

These reference sequences are curated independently of the genome annotation cycle, so their versions may not match the RefSeq versions in the current genome build. Identify version mismatches by comparing the version of the RefSeq in this section to the one reported in Genomic regions, transcripts, and products above.

mRNA and Protein(s)

  1. NM_001329678.2 → NP_001316607.1  protein PAXX isoform 1

    Status: REVIEWED

    Description
    Transcript Variant: This variant (1) encodes the longer isoform (1).
    Source sequence(s)
    AL807752

  2. NM_183241.3 → NP_899064.1  protein PAXX isoform 2

    See identical proteins and their annotated locations for NP_899064.1

    Status: REVIEWED

    Source sequence(s)
    BC002613
    Consensus CDS
    CCDS7020.1
    UniProtKB/Swiss-Prot
    Q8IY19, Q9BUH6
    Related
    ENSP00000360682.3, ENST00000371620.4
    Conserved Domains (1) summary
    pfam15384
    Location:8 → 204
    PAXX; PAXX, PAralog of XRCC4 and XLF, also called C9orf142

RNA

  1. NR_138073.2 RNA Sequence

    Status: REVIEWED

    Source sequence(s)
    AL807752
    Related
    ENST00000924669.1

  2. NR_138074.2 RNA Sequence

    Status: REVIEWED

    Source sequence(s)
    AL807752

  3. NR_138075.2 RNA Sequence

    Status: REVIEWED

    Source sequence(s)
    AL807752

  4. NR_138076.2 RNA Sequence

    Status: REVIEWED

    Source sequence(s)
    AL807752

  5. NR_138077.2 RNA Sequence

    Status: REVIEWED

    Source sequence(s)
    AL807752

RefSeqs of Annotated Genomes: GCF_000001405.40-RS_2025_08

The following sections contain reference sequences that belong to a specific genome build. Explain

Reference GRCh38.p14 Primary Assembly

Genomic

  1. NC_000009.12 Reference GRCh38.p14 Primary Assembly

    Range
    136992422..136993976
    Download
    GenBank, FASTA, Sequence Viewer (Graphics)

Alternate T2T-CHM13v2.0

Genomic

  1. NC_060933.1 Alternate T2T-CHM13v2.0

    Range
    149226833..149228387
    Download
    GenBank, FASTA, Sequence Viewer (Graphics)
Nucleotide Protein
Heading Accession and Version
Protein Accession Links
GenPept Link UniProtKB Link
Q9BUH6.2 GenPept UniProtKB/Swiss-Prot:Q9BUH6

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