Affinage

MTBP

Mdm2-binding protein · UniProt Q96DY7

Length
904 aa
Mass
102.2 kDa
Annotated
2026-04-28
40 papers in source corpus 19 papers cited in narrative 19 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

MTBP is a multifunctional scaffolding protein with central roles in DNA replication origin firing, p53 homeostasis, spindle assembly checkpoint signaling, and metastasis suppression. As the metazoan ortholog of yeast Sld7, MTBP forms an obligate elongated tetramer with Treslin/TICRR that is rate-limiting for replication initiation: its C-terminal CTM domain binds dsDNA and G-quadruplex DNA to direct chromatin localization and Cdc45 loading, with origin firing controlled by opposing CDK/DDK phosphorylation (promoting) and checkpoint kinase/RIF1-PP1 phosphorylation (inhibiting), and the complex acting transiently at pre-replication complexes to sense replication completion independently of ATR/CHK1 (PMID:28877985, PMID:34699733, PMID:36049481, PMID:33608586, PMID:41331242). MTBP also stabilizes MDM2 and promotes MDM2-mediated p53 ubiquitination, localizes to kinetochores in prometaphase to recruit the Mad1/Mad2 checkpoint complex, and serves as a transcriptional cofactor for MYC and ETS-1 at target promoters (PMID:15632057, PMID:21274008, PMID:24786788, PMID:36106099). MTBP suppresses metastasis in vivo by inhibiting ACTN4-mediated F-actin bundling and by blocking importin-7-dependent nuclear import of phospho-Erk1/2, and homozygous Mtbp deletion in mice is embryonic lethal (PMID:17906694, PMID:22370640, PMID:29765550).

Mechanistic history

Synthesis pass · year-by-year structured walk · 13 steps
  1. 2000 High

    Identifying MTBP as an MDM2-binding protein that induces G1 arrest established the gene as a participant in MDM2-regulated growth control, raising the question of whether MTBP modulates p53.

    Evidence Yeast two-hybrid screen with MDM2 bait plus cell cycle analysis of MTBP-overexpressing cells

    PMID:10906133

    Open questions at the time
    • Mechanism of G1 arrest unclear
    • Direct effect on p53 not tested
    • Endogenous interaction not confirmed
  2. 2005 High

    Demonstrating that MTBP promotes MDM2-mediated p53 ubiquitination and stabilizes MDM2 in a RING-finger-dependent manner resolved how MTBP fits into the MDM2-p53 axis, showing it amplifies p53 degradation under unstressed conditions.

    Evidence siRNA knockdown, in vivo ubiquitination assays, co-immunoprecipitation, RING domain mutant analysis

    PMID:15632057

    Open questions at the time
    • Structural basis of MTBP-MDM2 interaction unknown
    • Whether MTBP has p53-independent essential functions not resolved
  3. 2007 High

    Genetic studies in mice showing embryonic lethality of Mtbp-null animals (not rescued by p53 loss) and enhanced metastasis in Mtbp-haploinsufficient mice established that MTBP has essential p53-independent functions and acts as a metastasis suppressor in vivo.

    Evidence Germline Mtbp knockout/heterozygous mice crossed with p53+/− mice, in vitro invasion assays

    PMID:17906694

    Open questions at the time
    • Molecular target(s) of MTBP in metastasis suppression unidentified
    • Essential embryonic function undefined
  4. 2011 High

    Discovery that MTBP localizes to kinetochores during prometaphase and recruits Mad1/Mad2 revealed a direct role in the spindle assembly checkpoint, explaining mitotic defects and aneuploidy upon MTBP depletion.

    Evidence Immunofluorescence, live-cell imaging, siRNA knockdown, overexpression in human cells

    PMID:21274008

    Open questions at the time
    • How MTBP is recruited to kinetochores unknown
    • Relationship between mitotic degradation of MTBP and checkpoint silencing not defined
  5. 2012 High

    Identification of ACTN4 as a physical partner of MTBP whose F-actin bundling and filopodia-promoting activities are directly inhibited by MTBP provided a molecular mechanism for MTBP's metastasis-suppressive function.

    Evidence Co-immunoprecipitation, mass spectrometry identification, F-actin bundling assays, migration assays

    PMID:22370640

    Open questions at the time
    • Whether ACTN4 inhibition accounts for all metastasis suppression unclear
    • In vivo validation of ACTN4 axis not performed
  6. 2014 High

    Showing that MTBP associates with MYC and its cofactors TIP48/TIP49 at promoters and enhances MYC-driven transcription and transformation established MTBP as a MYC transcriptional cofactor, linking it to oncogenic proliferation.

    Evidence Chromatin immunoprecipitation, co-immunoprecipitation, reporter assays, transformation and tumor assays

    PMID:24786788

    Open questions at the time
    • Whether MTBP is required for endogenous MYC target gene expression genome-wide unknown
    • Structural basis of MTBP-MYC interaction not defined
  7. 2017 High

    Demonstrating that MTBP contains a Sld7-homologous CTM domain that binds dsDNA/G4-DNA and is essential for Cdc45 loading established MTBP as the metazoan Sld7 ortholog and defined its role in DNA replication origin firing.

    Evidence Xenopus egg extract depletion/add-back, in vitro DNA-binding assays, chromatin fractionation, mutagenesis in human cells

    PMID:28877985

    Open questions at the time
    • Whether CTM DNA binding determines origin specificity not established
    • Stoichiometry of Treslin-MTBP complex not yet defined
  8. 2018 Medium

    Finding that MTBP blocks nuclear import of phospho-Erk1/2 by binding importin-7 provided a second mechanism for metastasis suppression through inhibition of Erk signaling to Elk-1 target genes.

    Evidence Co-immunoprecipitation, nuclear fractionation, luciferase reporter array, migration assays in HCC cells

    PMID:29765550

    Open questions at the time
    • Single-lab finding not independently replicated
    • Whether importin-7 binding is direct and stoichiometric not confirmed
    • Relative contribution of Erk vs ACTN4 pathways to metastasis suppression unknown
  9. 2020 High

    Genome-wide ChIP-seq mapping of Treslin-MTBP binding to >30,000 sites at open chromatin, G4-DNA, and H3K4me2-marked nucleosomes revealed how the complex selects replication origins through coordinated recognition of multiple genomic signals.

    Evidence ChIP-seq in human cells with correlation to histone mark and chromatin accessibility datasets

    PMID:32966791

    Open questions at the time
    • Causal contribution of individual binding determinants not tested by mutagenesis at genomic scale
    • Whether binding sites correspond to active origins genome-wide not directly shown
  10. 2021 High

    Characterizing MTBP as a phosphorylation-regulated platform — where CDK phospho-mimetic mutations promote origin firing and checkpoint kinase phospho-mimetic mutations inhibit it — and defining the Treslin-MTBP tetramer as rate-limiting for initiation established the regulatory logic of origin firing control through MTBP.

    Evidence Phospho-mimetic/non-phosphorylatable mutant analysis of origin firing in human cells; immunodepletion and stoichiometric analysis in Xenopus egg extracts

    PMID:33608586 PMID:34699733

    Open questions at the time
    • Direct structural basis for how phosphorylation alters Treslin-MTBP interactions not resolved
    • Identity of checkpoint kinase(s) phosphorylating MTBP in vivo not confirmed
  11. 2022 High

    Demonstrating that Treslin-MTBP acts transiently at pre-RCs and is released after Cdc45 recruitment, and that this dynamic behavior senses replication completion independently of ATR/CHK1, established a novel checkpoint-independent S-phase monitoring mechanism.

    Evidence Live-cell imaging, kinase inhibitor experiments, flow cytometry, TRESLIN-MTBP depletion in human cells

    PMID:36049481

    Open questions at the time
    • Molecular mechanism sensing completion rate not defined
    • Whether this monitoring system operates in all cell types unknown
  12. 2024 Medium

    Identification of MTBP as an ETS-1 transcriptional co-activator at the MMP1 promoter extended its cofactor role beyond MYC, suggesting broader transcriptional functions.

    Evidence ChIP, luciferase reporter assays, overexpression/knockdown in HCC cells, xenograft

    PMID:36106099

    Open questions at the time
    • Generality of ETS-1 co-activation beyond MMP1 not tested genome-wide
    • Single-lab finding in HCC context
  13. 2025 High

    Genome-wide mapping of MTBP loading revealed that opposing DDK/RIF1-PP1 phosphorylation events on MCM2-7 determine Treslin-MTBP recruitment to initiation zones and establish replication timing, while CUT&RUN showed two distinct modes of MTBP chromatin binding in G1 vs S phase independent of licensed origins.

    Evidence Genome-wide factor mapping with auxin-inducible degron depletion; CUT&RUN with Geminin block of licensing

    PMID:40624716 PMID:41331242

    Open questions at the time
    • What determines the switch between G1 and S-phase binding modes unknown
    • Whether G1 binding has a function independent of replication

Open questions

Synthesis pass · forward-looking unresolved questions
  • The structural basis for how MTBP integrates its diverse functions — MDM2 binding, kinetochore recruitment, ACTN4 inhibition, transcriptional co-activation, and DNA replication — and whether these represent temporally exclusive or concurrent activities remains unresolved.
  • No high-resolution structure of full-length MTBP or its complexes with partners
  • How MTBP is partitioned among its multiple functions during the cell cycle is not defined
  • Whether the allosteric activation of Cdk8/19-CycC by MTBP operates in vivo awaits peer-reviewed validation

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0003677 DNA binding 3 GO:0060090 molecular adaptor activity 3 GO:0098772 molecular function regulator activity 3 GO:0140110 transcription regulator activity 2
Localization
GO:0005694 chromosome 5 GO:0005634 nucleus 3 GO:0005829 cytosol 1
Pathway
R-HSA-69306 DNA Replication 7 R-HSA-1640170 Cell Cycle 4 R-HSA-5357801 Programmed Cell Death 3 R-HSA-74160 Gene expression (Transcription) 2
Partners
ACTN4ETS1IPO7MAD1L1MAD2L1MDM2MYCTICRR
Complex memberships
Mad1/Mad2 checkpoint complex (recruited by MTBP)Treslin-MTBP tetramer

Evidence

Reading pass · 19 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2000 MTBP was identified as a novel MDM2-binding protein via yeast two-hybrid screen; MTBP induces G1 arrest that is suppressed by MDM2, suggesting MDM2 regulates a growth control pathway through MTBP. Yeast two-hybrid screen, cell cycle analysis, overexpression/suppression assays The Journal of biological chemistry High 10906133
2005 MTBP promotes MDM2-mediated ubiquitination and proteasomal degradation of p53 and stabilizes MDM2 in an MDM2 RING finger-dependent manner; siRNA knockdown of MTBP in unstressed cells elevates p53 levels and activity. Following UV (but not gamma-irradiation), MTBP is itself destabilized as part of the stress response. siRNA knockdown, ubiquitination assays, co-immunoprecipitation, Western blotting Molecular and cellular biology High 15632057
2007 Homozygous deletion of Mtbp in mice causes early embryonic lethality not rescued by p53 loss; heterozygous Mtbp loss in p53+/- mice significantly increases metastatic tumor development, and Mtbp downmodulation in osteosarcoma cells increases invasiveness while overexpression inhibits it, establishing MTBP as a metastasis suppressor in vivo. Germline knockout mice, in vitro migration/invasion assays, in vivo tumor studies Oncogene High 17906694
2011 MTBP protein is rapidly degraded during mitosis; a portion localizes to kinetochores during prometaphase and is required for recruiting/retaining the Mad1/Mad2 spindle assembly checkpoint complex at kinetochores. MTBP overexpression delays mitotic progression and causes abnormal chromosome segregation; knockdown leads to abbreviated metaphase, aneuploidy, senescence, and cell death similar to Mad2 depletion. Immunofluorescence, live-cell imaging, siRNA knockdown, overexpression, flow cytometry Cell death and differentiation High 21274008
2012 MTBP interacts with alpha-actinin-4 (ACTN4) as identified by co-immunoprecipitation and mass spectrometry; MTBP overexpression inhibits ACTN4-mediated cell migration, filopodia formation, and F-actin bundling. Nuclear localization of MTBP is dispensable for this inhibition of ACTN4-mediated migration. Co-immunoprecipitation, mass spectrometry, overexpression/knockdown, migration assays, immunofluorescence Oncogene High 22370640
2014 MTBP binds MYC transcriptional cofactors TIP48 and TIP49 as well as MYC itself; MTBP associates with MYC at promoters and increases MYC-mediated transcription, proliferation, neoplastic transformation, and tumor development. Co-immunoprecipitation, chromatin immunoprecipitation, reporter assays, transformation/tumor assays Cancer research High 24786788
2017 MTBP contains a C-terminal domain (CTM domain) with homology to yeast Sld7 that binds double-stranded DNA and G-quadruplex DNA; this domain is essential for MTBP chromatin localization and Cdc45 loading. Depletion of MTBP from Xenopus egg extracts abolishes DNA replication, and rescue requires the Treslin-MTBP complex together, not either protein alone. CTM domain mutants display severe S-phase defects in human cells. Xenopus egg extract depletion/add-back, DNA binding assays, chromatin fractionation, mutagenesis, human cell S-phase analysis Molecular biology of the cell High 28877985
2018 MTBP inhibits nuclear translocation of phosphorylated Erk1/2 (p-Erk) by binding to importin-7/RanBP7 (IPO7), thereby suppressing Elk-1 phosphorylation and transcription of Elk-1 target genes, reducing HCC cell migration. Luciferase reporter array, co-immunoprecipitation, phosphorylation assays, nuclear fractionation, qRT-PCR Oncotarget Medium 29765550
2020 The Treslin-MTBP complex binds to at least 30,000 sites in the human genome; binding sites predominantly reside in open chromatin regions with transcriptional-regulatory elements (promoters, enhancers, super-enhancers) and encompass nucleosome-free sequences (G-quadruplex DNA or AP-1 motif) and nucleosomes with H3K4me2, indicating coordinated recognition of multiple genomic signals to promote replication initiation. Genome-wide ChIP-seq/ChIP, chromatin fractionation, comparison with histone mark datasets Cell reports High 32966791
2021 MTBP is phosphorylated by CDK (cyclin-dependent kinases) at CDK consensus sites and by Cdk8/19-CycC, and phospho-mimetic CDK site mutants promote origin firing in human cells, while non-phosphorylatable mutants do not. MTBP is also phosphorylated at DNA damage checkpoint kinase consensus sites; phospho-mimetic mutations at these sites inhibit origin firing, establishing MTBP as a phosphorylation-regulated platform for origin firing control. Phospho-proteomics, phospho-mimetic and non-phosphorylatable mutant analysis, origin firing assays in human cells Scientific reports High 33608586
2021 In Xenopus egg extract, MTBP forms an elongated tetramer with Treslin containing two molecules of each protein; the Treslin-MTBP complex is rate-limiting for replication initiation, is recruited to chromatin before S phase, and DDK activity both increases and strengthens Treslin-MTBP interaction with licensed chromatin and cooperates with CDK to drive Treslin-MTBP interaction with TopBP1. Immunodepletion, add-back, structural analysis (elongated tetramer), chromatin recruitment assays, kinase inhibition in Xenopus egg extract Open biology High 34699733
2022 The TRESLIN-MTBP complex acts transiently at pre-replication complexes to initiate origin firing and is released after CDC45 recruitment; this dynamic behavior implements a monitoring system that senses the rate of origin firing to prevent premature S/G2 transition independently of ATR/CHK1 kinases. Live-cell imaging, cell synchronization, kinase inhibitor experiments, flow cytometry, TRESLIN-MTBP depletion Molecular cell High 36049481
2023 C9orf142 transcriptionally activates MTBP expression (demonstrated by ChIP and dual-luciferase reporter assays), and MTBP in turn regulates the MDM2/p53/p21 signaling axis and G1-to-S phase cell cycle transition; MTBP knockdown attenuates C9orf142-mediated tumor growth and metastasis. ChIP, dual-luciferase reporter assays, siRNA knockdown, in vivo tumor assays Clinical and translational medicine Medium 38009308
2025 TRESLIN-MTBP is identified as a key limiting firing factor for replication initiation; its loading onto phosphorylated MCM2-7 double hexamer is controlled by opposing phosphorylation events by DDK and RIF1-PP1, which determine initiation zones and establish replication timing. Genome-wide mapping of replication factors, auxin-inducible degron depletion, phosphorylation analysis, temporal origin firing mapping Nature communications High 41331242
2025 MTBP is a second allosteric activator of Cdk8/19-CycC kinase (distinct from Med12); MTBP directly repositions the T-loop of Cdk8/19 independently of T-loop phosphorylation to activate kinase activity in vitro, and targets Cdk8/19-CycC to Med12-independent cellular roles including replication origin firing regulation. In vitro kinase assays, structural analysis, mutagenesis, comparison with Med12 activation mechanism bioRxivpreprint Medium bio_10.1101_2025.06.16.659917
2025 CDK activity controls the abundance and chromatin recruitment of TRESLIN and MTBP; WEE1 inhibition (increasing CDK activity) blocks PCNA-dependent degradation of TRESLIN and enhances chromatin association of both TRESLIN and MTBP, promoting dormant origin firing. A conserved sequence in TRESLIN mediates its CDK-sensitive degradation, and MTBP is required for the elevated helicase recruitment under CDK-hyperactive conditions. WEE1/CDK inhibitor treatments, PCNA-dependent degradation assays, chromatin fractionation, siRNA knockdown, helicase loading assays bioRxivpreprint Medium bio_10.1101_2025.06.10.657920
2025 During G1, MTBP chromatin binding is dependent on TRESLIN for proper association with chromatin; in S phase, MTBP binding pattern and footprint differ from G1, implicating two separate modes of chromatin binding. Neither TRESLIN nor MTBP requires interaction with licensed MCM-loaded origins for their G1 chromatin binding. CUT&RUN genomic mapping, G1 synchronization, Geminin overexpression to inhibit licensing, siRNA knockdown Genome biology Medium 40624716
2015 MTBP endogenously interacts with ACTN4 and suppresses ACTN4-mediated cell migration in multiple HCC cell lines; in some HCC cellular contexts (PLC/PRF/5 cells), MTBP inhibits migration through ACTN4-independent pathways. MTBP expression is increased by histone deacetylase inhibitors, suggesting epigenetic regulation. Co-immunoprecipitation, migration assays, siRNA knockdown, HDAC inhibitor treatment Clinical & experimental metastasis Medium 25759210
2024 MTBP functions as a co-activator of transcription factor ETS-1 in HCC; MTBP enhances ETS-1 transcriptional activity and its recruitment to the MMP1 promoter, as shown by chromatin immunoprecipitation and luciferase assays, thereby promoting HCC cell proliferation. Chromatin immunoprecipitation, luciferase reporter assays, overexpression/knockdown, in vivo xenograft Frontiers in oncology Medium 36106099

Source papers

Stage 0 corpus · 40 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2000 A novel cellular protein (MTBP) binds to MDM2 and induces a G1 arrest that is suppressed by MDM2. The Journal of biological chemistry 90 10906133
2005 Regulation of p53 and MDM2 activity by MTBP. Molecular and cellular biology 62 15632057
2012 MTBP suppresses cell migration and filopodia formation by inhibiting ACTN4. Oncogene 47 22370640
2017 MTBP, the partner of Treslin, contains a novel DNA-binding domain that is essential for proper initiation of DNA replication. Molecular biology of the cell 39 28877985
2014 Oncogenic protein MTBP interacts with MYC to promote tumorigenesis. Cancer research 38 24786788
2014 MTBP is overexpressed in triple-negative breast cancer and contributes to its growth and survival. Molecular cancer research : MCR 34 24866769
2007 Mtbp haploinsufficiency in mice increases tumor metastasis. Oncogene 27 17906694
2021 The role of DDK and Treslin-MTBP in coordinating replication licensing and pre-initiation complex formation. Open biology 23 34699733
2020 Binding of the Treslin-MTBP Complex to Specific Regions of the Human Genome Promotes the Initiation of DNA Replication. Cell reports 22 32966791
2011 MTBP plays a crucial role in mitotic progression and chromosome segregation. Cell death and differentiation 22 21274008
2011 Loss of MTBP expression is associated with reduced survival in a biomarker-defined subset of patients with squamous cell carcinoma of the head and neck. Cancer 22 21692053
2021 Long Non-Coding RNA CRYBG3 Promotes Lung Cancer Metastasis via Activating the eEF1A1/MDM2/MTBP Axis. International journal of molecular sciences 20 33809929
2015 MTBP inhibits migration and metastasis of hepatocellular carcinoma. Clinical & experimental metastasis 20 25759210
2019 MTBP regulates cell survival and therapeutic sensitivity in TP53 wildtype glioblastomas. Theranostics 19 31534534
2018 MTBP inhibits the Erk1/2-Elk-1 signaling in hepatocellular carcinoma. Oncotarget 19 29765550
2022 The TRESLIN-MTBP complex couples completion of DNA replication with S/G2 transition. Molecular cell 18 36049481
2022 MTBP and MYC: A Dynamic Duo in Proliferation, Cancer, and Aging. Biology 14 35741402
2018 MTBP promotes migration and invasion by regulation of ZEB2-mediated epithelial-mesenchymal transition in lung cancer cells. OncoTargets and therapy 14 30349307
2015 MTBP Promotes the Invasion and Metastasis of Hepatocellular Carcinoma by Enhancing the MDM2-Mediated Degradation of E-Cadherin. Digestive diseases and sciences 14 26280083
2021 MTBP phosphorylation controls DNA replication origin firing. Scientific reports 13 33608586
2012 The enhancement of stability of p53 in MTBP induced p53-MDM2 regulatory network. Bio Systems 12 23059707
2016 Haploinsufficiency of the Myc regulator Mtbp extends survival and delays tumor development in aging mice. Aging 9 27803394
2022 MTBP enhances the activation of transcription factor ETS-1 and promotes the proliferation of hepatocellular carcinoma cells. Frontiers in oncology 8 36106099
2021 MTBP promoted the proliferation, migration and invasion of colon cancer cells by activating the expression of ZEB2. Animal cells and systems 8 34262658
2017 Whole genome sequencing identifies missense mutation in MTBP in Shar-Pei affected with Autoinflammatory Disease (SPAID). BMC genomics 8 28472921
2006 Telomere and TRF2/MTBP localization in respect to satellite DNA during the cell cycle of mouse cell line L929. Rejuvenation research 8 16859480
2003 Telomere-binding TRF2/MTBP localization during mouse spermatogenesis and cell cycle of the mouse cells L929. Journal of anti-aging medicine 8 14614800
2003 A telomere-binding protein (TRF2/MTBP) from mouse nuclear matrix with motives of an intermediate filament-type rod domain. Journal of anti-aging medicine 8 14987434
2023 C9orf142 transcriptionally activates MTBP to drive progression and resistance to CDK4/6 inhibitor in triple-negative breast cancer. Clinical and translational medicine 5 38009308
2022 The Role of MTBP as a Replication Origin Firing Factor. Biology 5 35741348
2025 Cell cycle-dependent TICRR/TRESLIN and MTBP chromatin binding mechanisms and patterns. Genome biology 4 40624716
2024 Cell Cycle-Dependent TICRR/TRESLIN and MTBP Chromatin Binding Mechanisms and Patterns. bioRxiv : the preprint server for biology 4 38370757
2019 [MTBP regulates migration and invasion of prostate cancer cells in vitro]. Nan fang yi ke da xue xue bao = Journal of Southern Medical University 4 30692060
2024 Circular RNA Circ_0000119 promotes gastric cancer progression via circ_0000119/miR-502-5p/MTBP axis. Gene 3 38378131
2018 Hyper expression of MTBP may be an adverse signal for the survival of some malignant tumors: A data-based analysis and clinical observation. Medicine 3 30170409
2007 Dynamics of satellite binding protein CENP-B and telomere binding protein TRF2/MTBP in the nuclei of mouse spermatogenic line. Cell biology international 2 17353134
2025 Unveiling the enigmatic role of MTBP in pan-cancer: A bioinformatics perspective. Pathology, research and practice 1 40680629
2025 The study of MDM2 binding protein (MTBP) in response to apoptosis in Litopenaeus vannamei under ammonia and nitrite nitrogen stress. Fish & shellfish immunology 0 41046925
2025 Regulated TRESLIN-MTBP loading governs initiation zones and replication timing in human DNA replication. Nature communications 0 41331242
2023 Characterization of an Mtbp Hypomorphic Allele in a Diethylnitrosamine-Induced Liver Carcinogenesis Model. Cancers 0 37760565