xpb xpb xpb (xeroderma pigmentosum type b) is an atp-dependent dna helicase in humans that is a part of the tfiih transcription factor complex. ercc3available structurespdbortholog search: pdbe rcsb list of pdb id codes4ern, 5iy9, 5ivw, 5iy7, 5iy8, 5iy6identifiersaliasesercc3, excision repair cross-complementation group 3, btf2, gtf2h, rad25, tfiih, xpb, ttd2, ercc excision repair 3, tfiih core complex helicase subunit, ssl2external idsomim: 133510 mgi: 95414 homologene: 96 genecards: ercc3 gene location (human)chr.chromosome 2 (human)band2q14.3start127,257,290 bpend127,294,166 bpgene location (mouse)chr.chromosome 18 (mouse)band18|18 b1start32,373,353 bpend32,403,204 bprna expression patternbgeehumanmouse (ortholog)top expressed insural nerveright uterine tubegastric mucosaganglionic eminenceanterior pituitarycanal of the cervixleft uterine tuberight coronary arteryskin of abdomengastrocnemius muscletop expressed inspermatidrenal corpusclemedullary collecting ductyolk sacmorulaseminiferous tubuleprimitive streakhair folliclespermatocyteduodenummore reference expression databiogpsmore reference expression datagene ontologymolecular function protein c-terminus binding nucleotide binding dna helicase activity protein kinase activity hydrolase activity atp-dependent activity, acting on dna protein n-terminus binding 3'-5' dna helicase activity atp binding damaged dna binding dna binding transcription factor binding protein binding helicase activity rna polymerase ii ctd heptapeptide repeat kinase activity atpase activity dna translocase activity cellular component transcription factor tfiih core complex nucleus nucleoplasm transcription factor tfiih holo complex transcription factor tfiid complex nucleotide-excision repair factor 3 complex transcription preinitiation complex biological process response to hypoxia termination of rna polymerase i transcription embryonic organ development transcription, dna-templated response to uv 7-methylguanosine mrna capping nucleotide-excision repair, dna incision regulation of mitotic cell cycle phase transition apoptotic process positive regulation of apoptotic process protein phosphorylation hair cell differentiation response to oxidative stress uv protection cellular response to dna damage stimulus transcription initiation from rna polymerase ii promoter global genome nucleotide-excision repair protein localization transcription elongation from rna polymerase ii promoter regulation of transcription, dna-templated positive regulation of transcription by rna polymerase ii dna topological change transcription initiation from rna polymerase i promoter transcription by rna polymerase ii transcription-coupled nucleotide-excision repair nucleotide-excision repair nucleotide-excision repair, preincision complex stabilization dna repair viral process nucleotide-excision repair, preincision complex assembly nucleotide-excision repair, dna incision, 5'-to lesion nucleotide-excision repair, dna duplex unwinding regulation of mitotic recombination promoter clearance from rna polymerase ii promoter transcription open complex formation at rna polymerase ii promoter regulation of transposition, rna-mediated phosphorylation of rna polymerase ii c-terminal domain regulation of rna polymerase ii regulatory region sequence-specific dna binding nucleotide-excision repair, dna incision, 3'-to lesion transcription elongation from rna polymerase i promoter sources:amigo / quickgoorthologsspecieshumanmouseentrez207113872ensemblensg00000163161ensmusg00000024382uniprotp19447p49135refseq (mrna)nm_000122nm_001303416nm_001303418nm_133658refseq (protein)np_000113np_001290345np_001290347np_598419location (ucsc)chr 2: 127.26 – 127.29 mbchr 18: 32.37 – 32.4 mbpubmed searchwikidataview/edit humanview/edit mouse structure 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. function 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). mutant xpb cells from individuals with the xpcs phenotype are sensitive to uv irradiation and acute oxidative stress. disorders 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. interactions xpb has been shown to interact with: bcr gene, cdk7, ercc2, gtf2h1, gtf2h2, gtf2h4, gtf2h5, p53, psmc5, and xpc. small molecule inhibitors 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.