XPB (xeroderma pigmentosum type B) is an ATP-dependent DNA helicase in humans that is a part of the TFIIH transcription factor complex.
ERCC3 | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Identifiers | |||||||||||||||||||||||||||||||||||||||||||||||||||
Aliases | ERCC3, excision repair cross-complementation group 3, BTF2, GTF2H, RAD25, TFIIH, XPB, TTD2, ERCC excision repair 3, TFIIH core complex helicase subunit, Ssl2 | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 133510 MGI: 95414 HomoloGene: 96 GeneCards: ERCC3 | ||||||||||||||||||||||||||||||||||||||||||||||||||
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The 3D-structure of the archaeal homolog of XPB has been solved by X-ray crystallography by Dr. John Tainer and his group at The Scripps Research Institute.[5]
XPB plays a significant role in normal basal transcription, transcription coupled repair (TCR), and nucleotide excision repair (NER). Purified XPB has been shown to unwind DNA with 3’-5’ polarity.
The function of the XPB(ERCC3) protein in NER is to assist in unwinding the DNA double helix after damage is initially recognized. NER is a multi-step pathway that removes a wide range of different DNA damages that distort normal base pairing. Such damages include bulky chemical adducts, UV-induced pyrimidine dimers, and several forms of oxidative damage. Mutations in the XPB(ERCC3) gene can lead, in humans, to xeroderma pigmentosum (XP) or XP combined with Cockayne syndrome (XPCS).[6] Mutant XPB cells from individuals with the XPCS phenotype are sensitive to UV irradiation and acute oxidative stress.[7]
Mutations in XPB and other related complementation groups, XPA-XPG, leads to a number of genetic disorders such as Xeroderma pigmentosum, Cockayne's syndrome, and trichothiodystrophy.
XPB has been shown to interact with:
Potent, bioactive natural products like triptolide that inhibit mammalian transcription via inhibition of the XPB subunit of the general transcription factor TFIIH has been recently reported as a glucose conjugate for targeting hypoxic cancer cells with increased glucose transporter expression.[18]