XPGNXeroderma pigmentosum G N-region
|SMART accession number:||SM00485|
|Description:||domain in nucleases|
|Interpro abstract (IPR006085):|
Xeroderma pigmentosum (XP) [(PUBMED:8160271)] is a human autosomal recessive disease, characterised by a high incidence of sunlight-induced skin cancer. People's skin cells with this condition are hypersensitive to ultraviolet light, due to defects in the incision step of DNA excision repair. There are a minimum of seven genetic complementation groups involved in this pathway: XP-A to XP-G. XP-G is one of the most rare and phenotypically heterogeneous of XP, showing anything from slight to extreme dysfunction in DNA excision repair [(PUBMED:8464724), (PUBMED:8206890)]. XP-G can be corrected by a 133 Kd nuclear protein, XPGC [(PUBMED:8160271)]. XPGC is an acidic protein that confers normal UV resistance in expressing cells [(PUBMED:8206890)]. It is a magnesium-dependent, single-strand DNA endonuclease that makes structure-specific endonucleolytic incisions in a DNA substrate containing a duplex region and single-stranded arms [(PUBMED:8206890), (PUBMED:8090225)]. XPGC cleaves one strand of the duplex at the border with the single-stranded region [(PUBMED:8090225)].
XPG belongs to a family of proteins that includes RAD2 from Saccharomyces cerevisiae (Baker's yeast) and rad13 from Schizosaccharomyces pombe (Fission yeast), which are single-stranded DNA endonucleases [(PUBMED:8090225), (PUBMED:8247134)]; mouse and human FEN-1, a structure-specific endonuclease; RAD2 from fission yeast and RAD27 from budding yeast; fission yeast exo1, a 5'-3' double-stranded DNA exonuclease that may act in a pathway that corrects mismatched base pairs; yeast DHS1, and yeast DIN7. Sequence alignment of this family of proteins reveals that similarities are largely confined to two regions. The first is located at the N-terminal extremity (N-region) and corresponds to the first 95 to 105 amino acids. The second region is internal (I-region) and found towards the C terminus; it spans about 140 residues and contains a highly conserved core of 27 amino acids that includes a conserved pentapeptide (E-A-[DE]-A-[QS]). It is possible that the conserved acidic residues are involved in the catalytic mechanism of DNA excision repair in XPG. The amino acids linking the N- and I-regions are not conserved.
This entry represents the N-terminal of XPG.
|GO process:||DNA repair (GO:0006281)|
|GO function:||nuclease activity (GO:0004518)|
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