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TFIIH
Transcription factor II Human (transcription factor II H; TFIIH) is an important protein complex, having roles in transcription of various protein-coding genes and DNA nucleotide excision repair (NER) pathways. TFIIH first came to light in 1989 when general transcription factor-δ or basic transcription factor 2 was characterized as an indispensable transcription factor in vitro. This factor was also isolated from yeast and finally named as TFIIH in 1992. TFIIH consists of ten subunits, 7 of which (ERCC2/XPD, ERCC3/XPB, GTF2H1/p62, GTF2H4/p52, GTF2H2/p44, GTF2H3/p34 and GTF2H5/TTDA) form the core complex. The cyclin activating kinase-subcomplex (CDK7, MAT1, and cyclin H) is linked to the core via the XPD protein. Two of the subunits, ERCC2/XPD and ERCC3/XPB, have helicase and ATPase activities and help create the transcription bubble. In a test tube these subunits are only required for transcription if the DNA template is not already denatured or if it is supercoiled. Two ot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GTF2H1
General transcription factor IIH subunit 1 is a protein that in humans is encoded by the ''GTF2H1'' gene. Interactions GTF2H1 has been shown to interact with: * Cyclin-dependent kinase 7, * E2F1, * ERCC2, * Estrogen receptor alpha, * TCEA1, and * XPB. See also * Transcription Factor II H Transcription factor II Human (transcription factor II H; TFIIH) is an important protein complex, having roles in transcription of various protein-coding genes and DNA nucleotide excision repair (NER) pathways. TFIIH first came to light in 1989 ... References Further reading * * * * * * * * * * * * * * * * * * External links * * {{NLM content Transcription factors ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleotide Excision Repair
Nucleotide excision repair is a DNA repair mechanism. DNA damage occurs constantly because of chemicals (e.g. intercalating agents), radiation and other mutagens. Three excision repair pathways exist to repair single stranded DNA damage: Nucleotide excision repair (NER), base excision repair (BER), and DNA mismatch repair (MMR). While the BER pathway can recognize specific non-bulky lesions in DNA, it can correct only damaged bases that are removed by specific glycosylases. Similarly, the MMR pathway only targets mismatched Watson-Crick base pairs. Nucleotide excision repair (NER) is a particularly important excision mechanism that removes DNA damage induced by ultraviolet light (UV). UV DNA damage results in bulky DNA adducts - these adducts are mostly thymine dimers and 6,4-photoproducts. Recognition of the damage leads to removal of a short single-stranded DNA segment that contains the lesion. The undamaged single-stranded DNA remains and DNA polymerase uses it as a templa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ERCC3
XPB (xeroderma pigmentosum type B) is an ATP-dependent DNA helicase in humans that is a part of the TFIIH transcription factor complex. 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 synd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ERCC2
__NOTOC__ ERCC2, or XPD is a protein involved in transcription-coupled nucleotide excision repair. The XPD (ERCC2) gene encodes for a 2.3-kb mRNA containing 22 exons and 21 introns. The XPD protein contains 760 amino acids and is a polypeptide with a size of 87kDa. Defects in this gene can result in three different disorders: the cancer-prone syndrome xeroderma pigmentosum complementation group D, photosensitive trichothiodystrophy, and Cockayne syndrome. Just like XPB, XPD is a part of human transcriptional initiation factor TFIIH and has ATP-dependent helicase activity. It belongs to the RAD3/XPD subfamily of helicases. XPD is essential for the viability of cells. Deletion of XPD in mice is lethal for developing embryos. Consequences of mutations in ERCC2 The ERCC2/XPD protein participates in nucleotide excision repair and is used in unwinding the DNA double helix after damage is initially identified. Nucleotide excision repair is a multi-step pathway that removes a wide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GTF2H2
General transcription factor IIH subunit 2 is a protein that in humans is encoded by the ''GTF2H2'' gene. Function This gene is part of a 500 kb inverted duplication on chromosome 5q13. This duplicated region contains at least four genes and repetitive elements which make it prone to rearrangements and deletions. The repetitiveness and complexity of the sequence have also caused difficulty in determining the organization of this genomic region. This gene is within the telomeric copy of the duplication. Deletion of this gene sometimes accompanies deletion of the neighboring SMN1 gene in spinal muscular atrophy (SMA) patients but it is unclear if deletion of this gene contributes to the SMA phenotype. This gene encodes the 44 kDa subunit of RNA polymerase II transcription initiation factor IIH which is involved in basal transcription and nucleotide excision repair. Transcript variants for this gene have been described, but their full length nature has not been determined. A second ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CDK7
Cyclin-dependent kinase 7, or cell division protein kinase 7, is an enzyme that in humans is encoded by the ''CDK7'' gene. The protein encoded by this gene is a member of the cyclin-dependent protein kinase (CDK) family. CDK family members are highly similar to the gene products of Saccharomyces cerevisiae cdc28, and Schizosaccharomyces pombe cdc2, and are known to be important regulators of cell cycle progression. This protein forms a trimeric complex with cyclin H and MAT1, which functions as a Cdk-activating kinase (CAK). It is an essential component of the transcription factor TFIIH, that is involved in transcription initiation and DNA repair. This protein is thought to serve as a direct link between the regulation of transcription and the cell cycle. Clinical significance eg cancer Given that CDK7 is involved in two important regulation roles, it's expected that CDK7 regulation may play a role in cancerous cells. Cells from breast cancer tumors were found to have elevate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GTF2H5
General transcription factor IIH subunit 5 is a protein that in humans is encoded by the ''GTF2H5'' gene. Function The ''GTF2H5(TTDA)'' gene encodes a small (71 amino acid) protein that stabilizes the multi-subunit transcription repair factor IIH(TFIIH). TFIIH plays a key role in a major DNA repair process, nucleotide excision repair (NER), by opening the DNA double helix after the initial recognition of damage in one strand. This step is followed by excision of the damaged region to generate a single-strand gap, and then repair synthesis, using the undamaged strand as template, to accurately fill in the gap. Disruption of the ''GTF2H5(TTDA)'' gene in a knockout mouse-model completely inactivates NER. In humans, mutation in any one of four genes can give rise to the trichothiodystrophy phenotype. These genes are ''TTDN1'', ''XPB'', ''XPD'' and ''GTF2H5(TTDA)''. Interactions GTF2H5 has been shown to interact with GTF2H2 and XPB XPB (xeroderma pigmentosum type B) is an AT ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclin H
Cyclin-H is a protein that in humans is encoded by the ''CCNH'' gene. Function The protein encoded by this gene belongs to the highly conserved cyclin family, whose members are characterized by a dramatic periodicity in protein abundance through the cell cycle. Cyclins function as regulators of CDK kinases. Different cyclins exhibit distinct expression and degradation patterns which contribute to the temporal coordination of each mitotic event. This cyclin forms a complex with CDK7 kinase and ring finger protein MAT1. The kinase complex is able to phosphorylate CDK2 and CDC2 kinases, thus functions as a CDK-activating kinase (CAK). This cyclin and its kinase partner are components of TFIIH, as well as RNA polymerase II protein complexes. They participate in two different transcriptional regulation processes, suggesting an important link between basal transcription control and the cell cycle machinery. Interactions Cyclin H has been shown to interact with P53, Cyclin-depende ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helicase
Helicases are a class of enzymes thought to be vital to all organisms. Their main function is to unpack an organism's genetic material. Helicases are motor proteins that move directionally along a nucleic acid phosphodiester backbone, separating two hybridized nucleic acid strands (hence '' helic- + -ase''), using energy from ATP hydrolysis. There are many helicases, representing the great variety of processes in which strand separation must be catalyzed. Approximately 1% of eukaryotic genes code for helicases. The human genome codes for 95 non-redundant helicases: 64 RNA helicases and 31 DNA helicases. Many cellular processes, such as DNA replication, transcription, translation, recombination, DNA repair, and ribosome biogenesis involve the separation of nucleic acid strands that necessitates the use of helicases. Some specialized helicases are also involved in sensing of viral nucleic acids during infection and fulfill a immunological function. Function Helicases are o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MAT1
CDK-activating kinase assembly factor MAT1 is an enzyme that in humans is encoded by the ''MNAT1'' gene. Function Cyclin-dependent kinases (CDKs), which play an essential role in cell cycle control of eukaryotic cells, are phosphorylated and thus activated by the CDK-activating kinase (CAK). CAK is a multisubunit protein that includes CDK7 (MIM 601955), cyclin H (CCNH; MIM 601953), and MAT1. MAT1 (for 'ménage à trois-1') is involved in the assembly of the CAK complex. upplied by OMIMref name="entrez"> Interactions MNAT1 has been shown to interact with: * Cyclin H, * Cyclin-dependent kinase 7, * Estrogen receptor alpha, * MCM7, * MTA1, * P53, and * POU2F1 POU domain, class 2, transcription factor 1 is a protein that in humans is encoded by the ''POU2F1'' gene. Interactions POU2F1 has been shown to interact with: * EPRS, * Glucocorticoid receptor, * Glyceraldehyde 3-phosphate dehydrogenase, .... References Further reading * * * * * * * * * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GTF2H4
General transcription factor IIH subunit 4 is a protein that in humans is encoded by the ''GTF2H4'' gene. Interactions GTF2H4 has been shown to interact with: * GTF2F1, * MED21, * POLR2A, * TATA binding protein, * Transcription Factor II B, and * XPB. See also * Transcription Factor II H Transcription factor II Human (transcription factor II H; TFIIH) is an important protein complex, having roles in transcription of various protein-coding genes and DNA nucleotide excision repair (NER) pathways. TFIIH first came to light in 1989 ... References Further reading * * * * * * * * * * * * * * * * * External links * Transcription factors {{gene-6-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xeroderma Pigmentosum
Xeroderma pigmentosum (XP) is a genetic disorder in which there is a decreased ability to repair DNA damage such as that caused by ultraviolet (UV) light. Symptoms may include a severe sunburn after only a few minutes in the sun, freckling in sun-exposed areas, dry skin and changes in skin pigmentation. Nervous system problems, such as hearing loss, poor coordination, loss of intellectual function and seizures, may also occur. Complications include a high risk of skin cancer, with about half having skin cancer by age 10 without preventative efforts, and cataracts. There may be a higher risk of other cancers such as brain cancers. XP is autosomal recessive, with mutations in at least nine specific genes able to result in the condition. Normally, the damage to DNA which occurs in skin cells from exposure to UV light is repaired by nucleotide excision repair. In people with xeroderma pigmentosum, this damage is not repaired. As more abnormalities form in DNA, cells malfunction and e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
