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APEX nuclease (multifunctional DNA repair enzyme) 1
Protein APEX1 PDB 1bix.png
PDB rendering based on 1bix.
Available structures
PDB Ortholog search: PDBe, RCSB
External IDs OMIM107748 MGI88042 HomoloGene1241 ChEMBL: 5619 GeneCards: APEX1 Gene
EC number
RNA expression pattern
PBB GE APEX1 210027 s at tn.png
More reference expression data
Species Human Mouse
Entrez 328 11792
Ensembl ENSG00000100823 ENSMUSG00000035960
UniProt P27695 P28352
RefSeq (mRNA) NM_001244249 NM_009687
RefSeq (protein) NP_001231178 NP_033817
Location (UCSC) Chr 14:
20.92 – 20.93 Mb
Chr 14:
50.92 – 50.93 Mb
PubMed search [1] [2]

DNA-(apurinic or apyrimidinic site) lyase is an enzyme that in humans is encoded by the APEX1 gene.

Apurinic/apyrimidinic (AP) sites (also called "abasic sites") occur frequently in DNA molecules by spontaneous hydrolysis, by DNA damaging agents or by DNA glycosylases that remove specific abnormal bases. AP sites are pre-mutagenic lesions that can prevent normal DNA replication. All cells, from simple prokaryotes to humans, have evolved systems to identify and repair such sites. Class II AP endonucleases cleave the phosphodiester backbone 5' to the AP site, thereby initiating a process known as base excision repair (BER). The APEX gene (alternatively named APE1, HAP1, APEN) encodes the major AP endonuclease in human cells. Splice variants have been found for this gene; all encode the same protein.[1]


APEX1 has been shown to interact with MUTYH,[2] Flap structure-specific endonuclease 1[3] and XRCC1.[4]


  1. ^ "Entrez Gene: APEX1 APEX nuclease (multifunctional DNA repair enzyme) 1". 
  2. ^ Parker, A; Gu Y; Mahoney W; Lee S H; Singh K K; Lu A L (February 2001). "Human homolog of the MutY repair protein (hMYH) physically interacts with proteins involved in long patch DNA base excision repair". J. Biol. Chem. (United States) 276 (8): 5547–55. doi:10.1074/jbc.M008463200. ISSN 0021-9258. PMID 11092888. 
  3. ^ Dianova, I I; Bohr V A; Dianov G L (October 2001). "Interaction of human AP endonuclease 1 with flap endonuclease 1 and proliferating cell nuclear antigen involved in long-patch base excision repair". Biochemistry (United States) 40 (42): 12639–44. doi:10.1021/bi011117i. ISSN 0006-2960. PMID 11601988. 
  4. ^ Vidal, A E; Boiteux S; Hickson I D; Radicella J P (November 2001). "XRCC1 coordinates the initial and late stages of DNA abasic site repair through protein-protein interactions". EMBO J. (England) 20 (22): 6530–9. doi:10.1093/emboj/20.22.6530. ISSN 0261-4189. PMC 125722. PMID 11707423. 

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