Topbp1 brct domains

Mar 12, 2015 The C-terminal region of TOPBP1 interacts with TOP2A, and TOPBP1 recruitment to UFBs requires its BRCT domain 5. TOPBP1 BRCT domains 0–2 and MDC1-pS168 phosphopeptide. Thus, TopBP1 may mediate the checkpoint function of 53BP1 in G1. Therefore, MEI1 is a BRCT-domain- containing protein that could be speci®c to the meiotic cell cycle and that plays a crucial role in some DNA repair events independent of SPO11 DSB recombination repair. They frequently occur in pairs, but can exist as singletons or in threes (e. TopBP1 has eight BRCT domains and a putative nuclear localization signal (NLS). This work reveals a novel BRCT binding mode and suggests a similar mechanism for TopBP1 interaction with 53BP1. The BRCT domains 4 and 5 (amino acids 534–763) of human TopBP1 were fused to LexA DNA binding domain in pLex-a vector . In addition, TopBP1 contains a putative ADP-ribosylation site, two N-terminal NLS domains, and 8 repeating BRCA1 C-terminal (BRCT) domains found in DNA repair proteins, such as BRCA1, XRCC1, and Rad4. Aug 10, 2001 Topoisomerase IIβ-binding protein (TopBP1), a human protein with eight BRCT domains, is similar toSaccharomyces cerevisiae Dpb11  TOPBP1. In this study, we identified MDC1, a key checkpoint protein involved in the cellular response to DNA double-strand breaks, as a TopBP1-associated protein. We also synthesized a degenerate phospho-peptide library based on the sequence of BACH1. S6). Locations of the novel mutants and the previously characterized mutant rad4-116 TopBP1 in each BRCT domain are marked. BRCT domain- containing protein TopBP1 functions in DNA replication and damage response. TopBP1 and homologues (TopBP1-family) are all ‘scaffold’ or ‘hub’ proteins that are able to make numerous protein–protein interactions through their constituent BRCT domains. The PARP-1 BRCT domain has the globular α/β fold of a canonical BRCT domain, with a core of four parallel β-strands, surrounded by α-helices (Figure 4). Structural alignment of the BRCT domain with the N-terminal BRCT domains of BRCA1 and MDC1 also confirm a The BRCT domain in the carboxyl terminus of the DNA repair protein XRCC1 . BRCT domain interactions are either phospho-dependent or -independent. Although the basis of these interactions remains to be described, structural Third BRCT domain of Topoisomerase (DNA) II binding protein 1; PDB rendering based on 1wf6. 2001 Aug 10;276(32):30399-406. The ATR activation domain (AAD) is located between BRCT domains 6 and 7. Here, we present the X-ray crystal structures of the tandem BRCT4/5 domains of TopBP1 free and in complex with a MDC1 consensus pSDpT phosphopeptide. Immunofluorescence analysis of African Green Monkey CV-1 (kidney epithelial) cells, staining TopBP1 with ab2402. Western blot analysis of TopBP1 on a TopBP1 serves as an activator of the ATR-ATRIP complex in response to the presence of incompletely replicated or damaged DNA. 87, 88 In the case of BRCA1, BRCT repeat-mediated DNA-binding activity is enhanced by formation of the BRCA1-BARD1 heterodimer. Mechanistically, TOPBP1 physically binds PLK1 and promotes PLK1 kinase–mediated phosphorylation of RAD51 at serine 14, a modification required for RAD51 recruitment to chromatin. BRCT domains are present in a large superfamily of ~40 nonorthologous proteins that participate in cell cycle checkpoints and in the DDR (14, 15). . Microcephalin (MCPH1/BRIT1) contains 3 BRCT domains; the second and third BRCT domains are required for binding to E2F1 . 101-189, 195-284, 354-444, 548-633, 641-738, 900-991, 1259-1351, 1389-1486) and two nuclear localization signal (NLS) motifs (a. TopBP1 BRCT4/5 adopts a variant BRCT-BRCT packing interface and recognizes its target peptide in a manner distinct from that observed in previous tandem BRCT- peptide structures. The specific TopBP1–MDC1 interaction is mediated by the fifth BRCT domain of TopBP1 and the Ser-Asp-Thr (SDT) repeats of MDC1. 1(A)]. TopBP1 has been linked to These proteins are grouped as having functional equivalence however at the sequence level they have different numbers of brct domains and the C terminal half is different between yeast and higher eukaryotes. S5). Like other BRCT domains, the overall fold of TopBP1 BRCT6 consists of a central four‐stranded parallel β‐sheet flanked on one side by a single helix (α 2) and on the opposite side by a pair of helices (α 1 and α 3) [Fig. The physiologic ligands of the BRCT domains of TopBP1 remain elusive, but the BRCT domains of BRCA1 are known to interact with BRCA1-associated COOH-terminal helicase 1 (BACH1) and with CtBP-interacting protein (CtIP; refs. 24– 26). DNA topoisomerase 2-binding protein 1 is an enzyme that in humans is encoded by the . The mutagen-sensitive-101 (mus101) gene of Drosophila melanogaster was first identified 25 years ago through mutations conferring larval hypersensitivity to DNA-damaging TopBP1 contains eight BRCT domains (Yamane et al, 1997; Garcia et al, 2005), of which six are arranged in pairs (BRCT domains 1–2, 4–5 and 7–8) and two are single (BRCT domains 3 and 6). Duplicate DOI to Aberrant expression of TopBP1 in breast cancer ="http://www. They are composed of multiple BRCT domains, some of which have the capacity to bind phosphorylated motifs in other proteins. TopBP1 and its homologues have been the subject of numerous scientific publications since the last comprehensive review in 2005, emerging as a key scaffold protein that links crucial 53BP1. Add BLAST: 91: Domain i: 548 – 633: BRCT 4 PROSITE-ProRule annotation BRCA1 C Terminus (BRCT) domain is a family of evolutionarily related proteins. Epub 2001 Jun 6. TopBP1 contains eight BRCT domains (Yamane et al, 1997; Garcia , 2005), of which six are arranged in pairs (BRCT domains 1–2, 4–5 and 7–8) and two are single (BRCT domains 3 and 6). TopBP1, a mediator protein containing multiple BRCT domains, binds to and activates the ATR/ATRIP complex through its ATR-Activation Domain (AAD). ac. It is named after the C-terminal domain of BRCA1, a DNA-repair protein that serves as a marker of breast cancer susceptibility. BRCA1 C Terminus (BRCT) domain is a family of evolutionarily related proteins. Add extension button. The BRCT domains 4–5 interacted with 53BP1 and recruitment of TopBP1 to sites of DNA DSBs in G1 was dependent on 53BP1. Homo sapiens (Human). Available structures; 1wf6: Identifiers; Symbols: TOPBP1; TOP2BP1: External IDs: OMIM: 607760 MGI: 1920018 HomoloGene: 38262 GeneCards: TOPBP1 Gene terminus (BRCT) repeats, as well as its ATR activation domain (AAD) that is particularly critical for its role in DNA replication stress signaling which initiates with ATR activation. BRCT domains are often found in pairs, and the interactions that they make are generally phospho-specific. TopBP1CT (encoding the C terminus of TopBP1) was identified in our yeast two-hybrid screen Upon gamma irradiation, TopBP1 colocalizes with Nbs1, BRCA1, and 53BP1 in the ionizing radiation-induced foci, where damaged DNA sites reside ( 18 , 22 , 36 ). Abstract. The interaction between SPBP and TopBP1 was confirmed in vitro and in vivo, and was found to be mediated by the Although dozens of protein–protein interactions (PPIs) involving the TopBP1 BRCT domains have been reported in the literature, how many of these distinct domains collaborate with different protein partners remains unclear. In Xenopus egg extracts, theN-terminalone-halfofTopBP1(BRCT domains I–IV) is necessary for loading of BRCT domains are versatile modules that mediate protein-protein and protein nucleic acid inter-actions (16). In mammals, surveillance mechanisms remove meiotic cells in which chromosome synapsis is defective. Thus, TopBP1 may localize topoisomerases to sites of DNA damage. K155E is a mutation in TOPBP1 BRCT domain 1; K250E is a mutation in BRCT domain 2. The PARP-1 BRCT domain has the  Previous GeneCards Identifiers for TOPBP1 Gene TOPBP1 (DNA Topoisomerase II Binding Protein 1) is a Protein Coding gene. uk/profile/14001"><span TopBP1 is key to ATR activation, and appears to first bind to DNA:pol-alpha, followed by a 9-1-1 complex and Rad17 interaction that leads to ATR stimulation. Structural analyses highlight a relatively conserved structure composed of two or three α helices surrounding a central β sheet. We fused either full-length The BRCT domain fold was first revealed in the crystal struc-ture of the X-ray repair cross-complementing protein 1 (XRCC1) N-terminal BRCT domain. Keywords: Arabidopsis, meiosis, MEI1, TopBP1, SpRAD4, BRCT domains. The TopBP1 BRCT domains define phospho-binding motifs , that allow TopBP1 to scaffold distinct proteins and protein complexes in response to the phosphorylation status of its clients. Furthermore, TOPBP1 BRCT domains 7/8 are essential for RAD51 foci formation. Upon DNA replication stress, TopBP1 is recruited to stalled replication forks through direct binding to the stalled forks (15, 16) or interaction of its first and second BRCT domains with the Rad9 –Hus1–Rad1 (9–1–1) clamp (17). It contains eight BRCT domains (aa 101-1486) that interact with distinct binding partners. a. Recruitment of TopBP1 to sites of DNA replication stress was dependent on BRCT domains 1–2 and 7–8, whereas recruitment to sites of DNA DSBs was dependent on BRCT domains 1–2 and 4–5. The source code for the WIKI 2 extension is being checked by specialists of the Mozilla Foundation, Google, and Apple. 852-858, 1517-1520). Topoisomerase II Binding Protein 1 (TopBP1) contains eight BRCT domains, which facilitate interaction with various proteins, phosphopeptides, and DNA. Fcp1 BRCT domain and TopBP1 BRCT6 bound to phosphorylated RNA polymerase II and E2F1, respectively (fig. In addition, TopBP1 has an ATR activation domain between BRCT domains 6 and 7 ( Kumagai et al , 2006 ; Mordes et al , 2008 ). The BRCT domains of TopBP1 have been shown to bind DNA breaks, DNA nicks, and DNA termini, but not circular intact DNA. TopBP1 (DNA topoisomerase IIbeta binding protein I) contains multiple BRCT domains and is involved in replication and the DNA damage checkpoint. Dotted line in-dicates threshold for specific protein-protein in-teractions. Once recruited, TopBP1 may activate ATM or ATR (see text for more details). Meiotic silencing. Organism. On the other hand, BRCT domains in Crb2 and TopBP1 do not have an R‐X‐X‐K motif. g. The BRCT domains 4-5 interacted with 53BP1 and recruitment of TopBP1 to sites of DNA DSBs in G1 was dependent on 53BP1. in TopBP1). pombe and A. Analysis of the TopBP1 and MDC1 BRCT domains suggests a similar approach is viable to design high affinity inhibitors. In addition, TopBP1 has an ATR activation domain between BRCT domains 6 and 7 (Kumagai et al, 2006; Mordes , 2008). This domain of about 95 amino acids is found in a large variety of proteins involved in DNA repair, recombination and cell cycle control [( PUBMED:8673121 ), ( PUBMED:9034168 ), ( PUBMED:9000507 )]. TopBP1 is a multi-BRCT-domain containing protein that acts to scaffold proteins during both the initiation of DNA replication and in response to DNA damage, a function dependent of the phospho-binding ability of the BRCT-domain pairs within TopBP1 . the BRCT domains in the yeast TOPBP1 homologues, and four in the vertebrate TOPBP1 homo- logues, possess the required cluster of residues needed to bind phosphorylated peptide motifs. , 2014) . ND = not determined. The phosphate-binding pocket and positively charged residues in a variant loop in BRCT5 present an extended binding surface for the negatively charged MDC1 phosphopeptide. Quite the same Wikipedia. In TOPBP1, this is located between BRCT domains 6 and 7, while in the yeast proteins it occurs at the C-terminus, downstream of BRCT4 (Wardlaw et al. As with the single BRCT domains of TopBP1 and XRCC1, tandem BRCT domains in BRCA1 and TopBP1 can also bind DNA strand breaks and ends in vitro. (2017) show that a single BRCT domain in TopBP1 binds tightly and specifically to phosphorylated Bloom syndrome helicase (BLM). It has been shown that the N terminal three The amino terminus of E2F1 interacts with 2 different proteins containing BRCA1 carboxy-terminal (BRCT) domains that have opposing activities in regulating E2F1-dependent transcription in response to DNA damage . TOPBP1 carries out most of its functions via nine BRCT domains that mediate phosphorylation-dependent protein–protein interactions Rad4 TopBP1 consists of four BRCT domains (R1, R2, R3, and R4) and two hydrophilic (acidic and basic) domains. w3. The recognition of the BACH1/FANCJ helicase by TopBP1 is critical for the activation of the DNA replication checkpoint at stalled replication forks and is facilitated by the C-terminal tandem BRCT7/8 domains of TopBP1 and a phosphorylated Thr1133 binding motif in BACH1. unit. PDF | TOPBP1 and its fission yeast homologueRad4, are critical players in a range of DNA replication, repair and damage signalling processes. Add BLAST: 90: Domain i: 354 – 444: BRCT 3 PROSITE-ProRule annotation. TopBP1 and its homologues have been the subject of numerous scientific publications since the last comprehensive review in 2005, emerging as a key scaffold protein that links crucial components within these distinct cellular processes. AB3245-I, is a highly specific rabbit polyclonal antibody that targets DNA topoisomerase 2-binding protein 1 (TopBP1) and has been tested in Immunoprecipitation and Western Blotting. gla. org/1999/xhtml"/>Retired, <a href TOPBP1 and its fission yeast homologue Rad4, are critical players in a range of DNA replication, repair and damage signalling processes. TOPBP1 and its fission yeast homologue Rad4, are critical players in a range of DNA replication, repair and damage signalling processes. They are composed of multiple BRCT domains, some of which bind phosphorylated motifs in other proteins. Human TopBP1 is 1522 amino acids (aa) in length. Ten additional tandem BRCT domains and three single BRCT domains preferentially bound phospho-peptides (fig. 97 Interestingly, TopBP1 BRCT7/8 also displays unique specificity for damaged DNA containing bulky lesions. Status. Depletion of TOPBP1  TopBP1 contains eight or nine BRCT domains (3,8). The Journal of Biological Chemistry. Domain i: 195 – 284: BRCT 2 PROSITE-ProRule annotation. Human TopBP1 is a large protein com-prising eight BRCA1 carboxyl-terminal (BRCT) domains distributed across its 1,522 amino acid length. Human DNA topoisomerase II binding protein 1 (TopBP1) contains eight BRCT BRCT domain-containing protein TopBP1 functions in DNA replication and  Aug 19, 2010 We have now determined the crystal structure of the N-terminal region of human TopBP1, revealing an unexpected triple-BRCT domain  Recruitment of TopBP1 to sites of DNA replication stress was dependent on BRCT domains 1–2 and 7–8, whereas recruitment to sites of DNA DSBs was  TopBP1 BRCT domains 1 and 2 bind Rad9. TopBP1 has eight BRCA1 carboxy-terminal (BRCT) domains and is involved in DNA replication, DNA damage responses and in the regulation of gene expression. Name:TOPBP1 Domaini, 195 – 284, BRCT 2PROSITE-ProRule annotation. The interaction between Rad9 and the BRCT domains 4–5 of TopBP1 is believed to recruit TopBP1 to DNA damage sites and activate the Chk1 checkpoint response (Greer et al, 2003; Furuya et al, 2004). BRCT domains of proteins are usually 80 to 100 amino acids in length and may occur in tandem as in BRCA1. TOPBP1, a DNA damage response protein, has a crucial role in meiotic sex chromosome silencing. This homology region includes the E2F1-binding domain (sixth to eighth BRCT domains) of TOPBP1; therefore, we speculated that MCPH1 could interact with and regulate E2F1. Comparison The BRCT domains 4–5 interacted with 53BP1 and recruitment of TopBP1 to sites of DNA DSBs in G1 was dependent on 53BP1. TopBP1 functions in the initiation of DNA replication and in the activation of ATR during the DNA damage response. Of the remaining BRCT domains in TopBP1, BRCT6 is implicated in binding to E2F1 (12) and PARP-1 (16), while BRCT domains 7 and 8 mediate interaction with the helicase BACH1/FANCJ (33). Diseases BRCT domain. thaliana indicate that the FCP1 BRCT domain is important for FCP1 C-terminal domain (CTD) phosphatase activity,34,35 structural The breast cancer susceptibility gene contains at its C terminus two copies of a conserved domain that was named BRCT for BRCA1 C terminus. TopBP1 is a nuclear protein with eight BRCT domains and is involved in many aspects of nucleic acid metabolism: it is involved in the initiation of DNA replication in the Xenopus in vitro replication system by assisting loading of polymerase onto the replication complex; it is a substrate for ATM/ATR and is essential for the ATR DNA damage signalling pathway, and is also probably involved in the actual DNA repair process; it acts as a transcriptional cofactor for E2F1 where it regulates the Human TopBP1 contains eight BRCA1 C Terminus (BRCT) domains (a. The homology between TopBP1 and Cut5/Rad4 or Dpb11 lies at its BRCT domains 1–2, and 4–5. In a second phase of recruitment TopBP1 is recruited by interacting via BRCT domains 1-2 with Nbs1 and via BRCT domains 4-5 with 53BP1. BRCT domains were initially recognized in the C-terminal region of BRCA1, a protein encoded by the major breast and ovarian susceptibility gene with pleiotropic roles in DNA damage repair . 15,16 BRCT domains occur in proteins as single (e. Therefore, proteins found to interact with BRCT domains are likely to have roles in the cellular response to DNA damage. One such surveillance mechanism is meiotic silencing, the transcriptional silencing of genes on asynapsed chromosomes. 15 The fold is comprised of a central 4-stranded β-sheet flanked by a single -helix (αα 2) on one side and two α-helices (α 1 and α 3) on the opposite side. The stimulation of TopBP1 on ataxia-telangiectasia mutated—and Rad3-related (ATR) activity was activated   Jul 22, 2003 Besides the BRCT domains, Arabidopsis MEI1 protein shares similarities with a family of proteins (TopBP1 in human, Rad4/Cut5 in  Jul 1, 2007 The physiologic ligands of the BRCT domains of TopBP1 remain elusive, but the BRCT domains of BRCA1 are known to interact with  In fact, BRCT and FHA domains are rarely found in cytosolic proteins, but they . Human DNA topoisomerase IIβ-binding protein 1 (TopBP1) and its orthologues in other organisms are proteins consisting of multiple BRCT modules that have acquired several functions during evolution. TopBP1 is a modular protein consisting of nine BRCT (BRCA1 C-terminal) domains (numbered from 0 to 8). It is also important to note that instances of either FHA or BRCT domains might also bind other proteins via more extensive surface interaction or via other linear motifs that do not depend on phosphorylation or other post‐translational modifications. Like other BRCT domains, the overall fold of TopBP1 BRCT6 consists of a central four-stranded parallel b-sheet flanked on one side by a single helix (a 2) and on the opposite side by a pair of helices (a 1 and a 3) [Fig. Mäkelä, Juhani E To establish whether the interaction of 53BP1 and TopBP1 was important for the function of TopBP1 in the G1 checkpoint, we generated stably‐transfected clones of U2OS cells expressing either GFP‐tagged full‐length TopBP1 or a TopBP1 mutant with BRCT domains 4–5 deleted (δ551–738; Figure 5D). TopBP1 displays increased binding to ATR-ATRIP in Xenopus egg extracts containing checkpoint-inducing DNA templates. They are composed of multiple BRCT domains, some of TOPBP1 contains 9 BRCT domains, some of which occur in tandem, whereas others appear to function as single domains (Figure 2A). Through its BRCT domain, TopBP1 interacts with and represses exclusively E2F1 but not other E2F factors. This process involves binding of ATR to the ATR-activating domain of TopBP1, which is located between BRCT domains VI and VII. In response to DNA damage, checkpoint signalling protects genome integrity at the cost of repressing cell cycle progression and DNA replication. Minna Mäkiniemi, Tomi Hillukkala, Jussi Tuusa, Kaarina Reini, Markku Vaara, Deqi Huang, Helmut Pospiech, Inkeri Majuri, Thomas Westerling, Tomi P. Just better. Human TopBP1 contains eight BRCA1 C Terminus (BRCT) domains (a. We show that Schizosaccharomyces pombe Rad4 TopBP1 AAD–defective strains are DNA damage sensitive during G1/S-phase, but not during G2. TopBP1 BRCT6 both purified and crystallized as a monomer, with one BRCT6 molecule present in the asymmetric unit. In this issue of Structure, Sun et al. (F) Fluorescence polarization with recombinant TOPBP1 BRCT domains 0–2 and MDC1-pS196 phosphopeptide. Domains that occur as single Therefore, MEI1 is a BRCT-domain- containing protein that could be speci®c to the meiotic cell cycle and that plays a crucial role in some DNA repair events independent of SPO11 DSB recombination repair. subsequent work on FCP1 and TopBP1 single BRCT domains provides conflicting evidence for their roles as phospho-peptide binding modules. Human TopBP1 contains nine BRCT domains and functions in DNA replication initiation, checkpoint signalling, DNA repair and influences transcriptional control. Jul 13, 2018 N-terminal BRCT domains of the DNA damage checkpoint proteins TOPBP1/ Rad4 display distinct specificities for phosphopeptide ligands. S/G2-phase. TopBP1 (through TopBP1 first and second BRCT domains) to promote DNA replication (14). homologue of Dpb11 (human TopBP1), which contains eight BRCT domains . BRCT domains are intimately connected to the regulation of DNA integrity. , TOPBP1). No. TopBP1 has eight BRCT (BRCA1 C-terminal) protein interaction domains and is multifunctional, also acting in DNA replication, DNA repair, and transcription. , PARP1) or multiple units (e. Each BRCT repeat adopts a characterized fold with a central, parallel four-stranded β -sheet, along with a pair of α -helices packed against one face and a single α -helix packed against the opposite face of the sheet. and the fifth to eighth BRCT domains of TOPBP1. Reviewed-Annotation . To further demonstrate that the binding of phospho-peptides is a general characteristic of BRCT domains, we examined the BRCT domain of Fcp1 and one of the BRCT domains of Top BP1 (BRCT6). TopBP1 contains repeats of the BRCA1 C-terminal (BRCT) domain and plays important roles in DNA damage response, DNA replication, and other cellular regulatory functions during the interphase. As TopBP1 contains a domain important for ATR activation, we examined whether it contributes to the G1 cell cycle checkpoint. Of the BRCT domains in TOPBP1, only 1, 2, 5, and 7 contain the necessary lysine residues required for phosphopeptide binding ( Leung and Glover, 2011 ). "BRCT domain-containing protein TopBP1 functions in DNA replication and damage response". Sigma-Aldrich offers abstracts and full-text articles by [M Mäkiniemi, T Hillukkala, J Tuusa, K Reini, M Vaara, D Huang, H Pospiech, I Majuri, T Westerling, T P Mäkelä, J E Syväoja]. BRCT domains, so-called due to their identification at the C-terminus of the BRCA1 protein, act as protein-protein interaction modules. Several BRCT domains recognize linear motifs phosphorylated by kinases that are activated by DNA damage ( 8, 9, 17). Although studies in S. Although dozens of protein–protein interactions (PPIs) involving the TopBP1 BRCT Immunocytochemistry/ Immunofluorescence - Anti-TopBP1 antibody - ChIP Grade (ab2402)This image is courtesy of an anonymous Abreview. Instead, they have an arginine at α1 helix, which composes the binding pocket with conserved T/S and K, and interacts with phospho‐serine directly 17 , 49 . Indeed, an interaction between endogenous MCPH1 and E2F1 was detected by reciprocal co- Human TopBP1 contains nine BRCT domains and functions in DNA replication initiation, checkpoint signalling, DNA repair and influences transcriptional control. 276 (32):  Oct 8, 2018 Structural and biochemical analyses of BRCT domain interactions defines TOPBP1/Rad4 selectivity for phosphorylated motifs, allowing  J Biol Chem. TopBP1 has eight BRCT [BRCA1 (breast-cancer susceptibility gene 1) C-terminus] domains and is involved in initiating DNA replication, and DNA damage checkpoint signalling and repair. , BRCA1). Human TopBP1 is a large protein comprising eight BRCA1 carboxyl-terminal (BRCT) domains distributed across its 1,522 amino acid length. They thus act as multi-point adaptors bringing proteins TOPBP1 and its fission yeast homologue Rad4, are critical players in a range of DNA replication, repair and damage signalling processes. Mechanisms for checkpoint down‐regulation are therefore necessary for proper cellular proliferation. TopBP1 (DNA topoisomerase IIbeta binding protein I) contains multiple BRCT domains and is involved in replication and the DNA damage checkpoint . In all eukaryotes, TopBP1 plays an essential role in the initiation of DNA replication [21] . The BRCT domains of TopBP1 are colored green; those domains that harbor lysines that are critical for recruitment of TopBP1 to Duplicate Title to Identification of TOPBP1 chromatin modification domains and transcriptional targets</a> <br xmlns="http://www. The BRCT domain consists of repeats containing approximately ~90-100 amino acids. TopBP1 likely participates in such diverse aspects of DNA metabolism by acting as a central component of multiple functionally distinct subcomplexes, but these various subcomplexes remain to be defined. Several BRCT-domain-containing proteins involved in mediating DNA repair have transcriptional regulatory domains, and as demonstrated for BRCA1 these regulatory domains are important in mediating the functions of these proteins. The closest structural homolog based on a Dali analysis [30] is the sixth BRCT domain of TopBP1 (TopBP1 BRCT6) [31] (Figure 5b). org/1999/xhtml"/>User Workarea, <a href="http://eprints. Interestingly, in pro-teins in which they occur as multiple units, BRCTs tend to be organized as pairs of closely juxtaposed units (e. Anti-TopBP1 Antibody, Cat. Topoisomerase IIbeta-binding protein (TopBP1), a human protein with eight BRCT domains, is similar to Saccharomyces cerevisiae Dpb11 and Schizosaccharomyces pombe Cut5 checkpoint proteins and closely related to Drosophila Mus101. That's it. Two BRCT domains in Rad4 TOPBP1 define a phospho-specific protein interaction In this report, we provide evidence that Rad3 ATR (and to a lesser extent Tel1 ATM) must phosphorylate the C terminus of Rad9 to promote association of Rad9 with Rad4 TOPBP1. A human peripheral lymphocyte cDNA library ( 39 ) was transformed into the L40 yeast strain expressing the LexA BRCT4+5 fusion. Through these interactions, TopBP1 functions in the regulation of DNA replication, DNA repair, checkpoint control, and transcription (1). By monitoring the entry of irradiated G1 cells into S‐phase, we observed a checkpoint defect after siRNA‐mediated depletion of TopBP1, 53BP1 or ATM. In prometaphase, metaphase, and anaphase, TopBP1 localizes to the mitotic centrosomes, which function as spindle-poles for the bipolar separation of sister chromatids. FHA domains have only been found present as isolated instances but BRCT domains present a more diverse domain arrangement: besides many occurrences of single and tandem BRCT domains it is also found as a triplet in TOPBP1 53, 54. Mammalian TopBP1 contains eight BRCA1 C-terminal (BRCT) domains that facilitate protein-protein interactions between key replication and checkpoint factors 11,12,13,14. Evaluation of these led to the identification of a peptide mimic 15 with a inhibitory constant (Ki) of 40 nM for BRCT(BRCA1). Thus, TopBP1 functions as a critical modulator and serves as a negative feedback regulator of E2F1 by inhibiting E2F1 -dependent apoptosis during G1/S transition as well as DNA damage to promote cell TOPBP1 localization to UFBs is mediated via its BRCT 4 and 5. (A) Schematic map of TopBP1 showing the BRCT domains, the AD, and the S-tagged constructs used in this study:  Oct 3, 2011 Here we present the solution structure and biophysical characterization of the BRCT domain of rat PARP-1. TOPBP1. TopBP1 is a nuclear protein with eight BRCT domains and is involved in many aspects of nucleic acid metabolism: it is involved in the initiation of DNA replication in the Xenopus in vitro replication system by assisting loading of polymerase onto the replication complex; it is a substrate for ATM/ATR and is essential for the ATR DNA damage signalling pathway, and is also probably involved in the actual DNA repair process; it acts as a transcriptional cofactor for E2F1 where it regulates the BRCT domains 0–2 and 4–5 are required for TopBP1-induced nucleolar segregation. It is named after the C-terminal domain of BRCA1 , a DNA-repair protein that serves as a marker of breast cancer susceptibility. TopBP1, Dpb11, at the C-terminus beyond the fourth BRCT domain (31,32). domains, and 8 repeating BRCA1 C-terminal (BRCT) domains found in DNA repair proteins, such as BRCA1, XRCC1, and Rad4. (B) Sensitivities of the rad4 TopBP1 mutants to genotoxic agents. topbp1 brct domains

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