XPB

XPB (xeroderma pigmentosum type B) is an ATP-dependent DNA helicase in humans that is a part of the TFIIH transcription factor complex.

ERCC3
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 4ERN, 5IY9, 5IVW, 5IY7, 5IY8, 5IY6
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; OMA:ERCC3 - orthologs
Gene location (Human) Chr. Chromosome 2 (human)[1] Band 2q14.3 Start 127,257,290 bp[1] End 127,294,166 bp[1]
Gene location (Mouse) Chr. Chromosome 18 (mouse)[2] Band 18|18 B1 Start 32,373,353 bp[2] End 32,403,204 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in sural nerve right hemisphere of cerebellum right uterine tube gastric mucosa gonad granulocyte ganglionic eminence body of uterus anterior pituitary canal of the cervix Top expressed in spermatid renal corpuscle granulocyte endothelial cell of lymphatic vessel ventricular zone epiblast tail of embryo medullary collecting duct lumbar spinal ganglion yolk sac More reference expression data BioGPS More reference expression data
Gene ontology Molecular 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 / QuickGO
Orthologs Species Human Mouse Entrez 2071 13872 Ensembl ENSG00000163161 ENSMUSG00000024382 UniProt P19447 P49135 RefSeq (mRNA) NM_000122 NM_001303416 NM_001303418 NM_133658 RefSeq (protein) NP_000113 NP_001290345 NP_001290347 NP_598419 Location (UCSC) Chr 2: 127.26 – 127.29 Mb Chr 18: 32.37 – 32.4 Mb PubMed search [3] [4]
Wikidata
View/Edit Human View/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.^[5]

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).^[6] Mutant XPB cells from individuals with the XPCS phenotype are sensitive to UV irradiation and acute oxidative stress.^[7]

XPB helicase is also a component of the p53-mediated programmed cell death (apoptosis) pathway.^[8]

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,^[9]
• CDK7,^[10][11][12]
• ERCC2,^{[10][13][14][15]}
• GTF2H1,^[10][11][13]
• GTF2H2,^[10][13]
• GTF2H4,^[10][13]
• GTF2H5,^[10]
• P53,^[16]
• PSMC5,^[17] and
• XPC.^[18]

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.^[19]

See also

• XP