{"gene":"PPP1R10","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":1998,"finding":"PNUTS (PPP1R10) was identified as a PP1-interacting protein that forms a stable complex with PP1 in mammalian cell lysates, potently modulates PP1 catalytic activity toward exogenous substrates in vitro, and exhibits discrete nuclear compartmentalization with co-localization with chromatin during mitosis.","method":"Yeast two-hybrid, co-immunoprecipitation from mammalian cell lysates, in vitro phosphatase activity assay, immunofluorescence","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, in vitro activity assay, and localization by immunofluorescence; independently replicated by Kreivi et al. (PMID:9450550) same year","pmids":["9461602"],"is_preprint":false},{"year":1997,"finding":"p99 (PPP1R10) was purified as a PP1 regulatory subunit from HeLa cell nuclei; recombinant p99 suppresses PP1 phosphorylase phosphatase activity by >90%; the PP1-binding motif contains an unusual tryptophan in place of the canonical phenylalanine; p99 shows punctate nucleoplasmic staining with nucleolar accumulations.","method":"Biochemical purification from HeLa nuclei, in vitro phosphatase activity assay, immunofluorescence, cDNA cloning","journal":"FEBS letters","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — in vitro reconstitution of PP1 inhibition, replicated by Allen et al. (PMID:9461602)","pmids":["9450550"],"is_preprint":false},{"year":2003,"finding":"A 50-amino acid central domain of PNUTS mediates high-affinity PP1 binding and inhibition of PP1 activity; the critical tryptophan residue within the RVXF-like motif is essential (W→A mutation abolishes PP1 binding and inhibition); protein kinase A phosphorylates this PP1-binding domain and substantially reduces PNUTS–PP1 interaction in vitro and in intact cells upon PKA stimulation; a C-terminal region containing RGG motifs and His/Gly-rich repeats binds mRNA and ssDNA with selectivity for poly(A) and poly(G); a PNUTS–PP1 complex can be isolated via RNA-conjugated beads.","method":"GST pulldown, FLAG-tagged protein expression in 293T cells, in vitro phosphatase assay, in vitro kinase assay (PKA), in vitro RNA binding, site-directed mutagenesis, truncation analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal methods (mutagenesis, in vitro assays, intact-cell PKA stimulation) in a single rigorous study","pmids":["12574161"],"is_preprint":false},{"year":2014,"finding":"PNUTS is intrinsically disordered in its free form and binds PP1 in a highly extended manner; PNUTS blocks one of PP1's substrate-binding grooves (the 'arginine site') while leaving the active site accessible, thereby inhibiting PP1-mediated dephosphorylation of Rb by blocking Rb's binding site on PP1; unique PP1-binding motifs defined by the PNUTS–PP1 structure allow prediction of how >25% of known PP1 regulators bind PP1.","method":"NMR structure determination, X-ray crystallography, biochemical binding assays, mutagenesis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — atomic-resolution structure with functional validation; multiple orthogonal structural and biochemical methods","pmids":["24591642"],"is_preprint":false},{"year":2005,"finding":"PNUTS co-fractionates with micrococcal nuclease-soluble chromatin in interphase and is targeted to reforming nuclei in telophase concomitant with chromatin decondensation; recombinant PNUTS(309-691) accelerates decondensation of prometaphase chromosomes in vitro in a manner requiring the RVXF PP1-binding motif (W401A mutation abolishes activity); PNUTS promotes decondensation via the PNUTS:PP1 holoenzyme in a defined buffer system with exogenous PP1.","method":"Subcellular fractionation, in vitro chromosome decondensation assay (cytosolic extract and defined buffer system), immunofluorescence, site-directed mutagenesis (W401A)","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — in vitro reconstitution with mutagenesis validation and two independent assay systems in one study","pmids":["15907195"],"is_preprint":false},{"year":2002,"finding":"PNUTS inhibits PP1c activity toward pRb; GST-PNUTS fusion protein inhibits pRb-directed PP1c activity using PP1c from cell lysates, GST-PP1c, or purified PP1c; PNUTS dissociates from PP1c under mildly hypoxic conditions coincident with increased PP1c activity toward pRb.","method":"In vitro pRb-directed phosphatase assay, GST pulldown, hypoxia treatment of cells","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro phosphatase assay with purified components and cell-based correlate; single lab, two orthogonal approaches","pmids":["12270115"],"is_preprint":false},{"year":2008,"finding":"Reduced expression of PNUTS in cancer cells increases PP1 activity toward Rb, leading to Rb dephosphorylation, dissociation of E2F1 from Rb, and caspase-8-dependent apoptosis; this effect requires Rb (no effect in Rb-null cells) and is p53-independent; normal cells are not affected by PNUTS knockdown.","method":"siRNA knockdown, cell viability assay, apoptosis assay, Rb-phosphatase activity assay, cell line panel (Rb-null vs. Rb-expressing)","journal":"Cancer biology & therapy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — defined genetic epistasis (Rb-null rescue), phosphatase activity assay, and phenotypic readout; single lab","pmids":["18360108"],"is_preprint":false},{"year":2010,"finding":"PNUTS depletion by siRNA activates a G2 checkpoint in unperturbed cells and prolongs G2 arrest and Chk1 activation after ionizing-radiation-induced DNA damage; overexpression of PNUTS-EGFP, which rapidly and transiently localizes to DNA damage sites, inhibits G2 arrest; PNUTS depletion causes prolonged γH2AX, 53BP1, RPA, and Rad51 foci and decreased clonogenic survival after irradiation.","method":"siRNA knockdown, live-cell imaging (PNUTS-EGFP recruitment to damage sites), flow cytometry (cell cycle), immunofluorescence (γH2AX, 53BP1, RPA, Rad51), clonogenic survival assay","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal readouts (live imaging, cell cycle analysis, DNA repair foci, survival) with gain- and loss-of-function in same study","pmids":["20890310"],"is_preprint":false},{"year":2012,"finding":"PNUTS directly interacts with the C2 (lipid-binding) domain of PTEN and sequesters PTEN in the nucleus; depletion of PNUTS leads to increased apoptosis and reduced proliferation in a PTEN-dependent manner.","method":"Co-immunoprecipitation, GST pulldown (domain mapping), siRNA knockdown, cell viability and apoptosis assays","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP plus domain-mapping pulldown, PTEN-dependent epistasis; single lab","pmids":["23117887"],"is_preprint":false},{"year":2018,"finding":"Endogenous MYC and PNUTS interact across multiple cell types and co-occupy MYC target gene promoters; PP1/PNUTS dephosphorylates MYC at multiple serine/threonine residues; inhibiting PP1 causes MYC hyperphosphorylation, proteasomal degradation via SCFFBXW7, and loss of MYC chromatin binding while retaining MAX interaction; rescue requires specifically PP1, not other phosphatases.","method":"BioID mass spectrometry, co-immunoprecipitation, ChIP, RNAi knockdown, pharmacological PP1 inhibition, phospho-site mass spectrometry","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (BioID, Co-IP, ChIP, mass spec, genetic and pharmacological perturbations) in one rigorous study","pmids":["30158517"],"is_preprint":false},{"year":2019,"finding":"PNUTS-PP1 is a negative regulator of RNA Pol II elongation rate; the PNUTS W401A mutation (disrupting PP1 binding) causes genome-wide acceleration of transcription associated with hyper-phosphorylation of the Spt5 elongation factor; Pol II decelerates immediately downstream of poly(A) sites, correlating with Spt5 dephosphorylation requiring poly(A) site recognition and the PNUTS-PP1 complex; PNUTS-PP1-dependent Pol II deceleration is required for transcription termination ('sitting duck torpedo' mechanism).","method":"TT-seq (transient transcriptome sequencing), ChIP-seq, site-directed mutagenesis (W401A), in vivo elongation rate measurement, phospho-Spt5 analysis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — genome-wide functional assay combined with mutagenesis and mechanistic epistasis, defining a new termination model","pmids":["31677974"],"is_preprint":false},{"year":2018,"finding":"PNUTS expression is elevated in mitosis; PNUTS depletion partially blocks mitotic entry and causes chromosome mis-segregation; Aurora A/B kinase complexes and kinetochore components are PNUTS-associated proteins; PNUTS depletion suppresses Aurora A/B activation and disrupts chromosomal passenger complex (CPC) spatiotemporal regulation; PNUTS dynamically localizes to kinetochores and is required for spindle assembly checkpoint activation.","method":"siRNA knockdown, co-immunoprecipitation/MS, immunofluorescence (kinetochore localization), kinase activity assay, live-cell imaging","journal":"Molecular cancer research : MCR","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP/MS with functional knockdown phenotypes and localization; single lab","pmids":["30190438"],"is_preprint":false},{"year":2020,"finding":"PNUTS-PP1 promotes RNAPII CTD dephosphorylation and suppresses replication stress; PNUTS depletion causes lower EdU uptake, S-phase accumulation, and slower replication fork rates; RNAPII has a longer chromatin residence time after PNUTS or WDR82 depletion; PNUTS and WDR82 promote proteasome-dependent degradation of RNAPII on chromatin; reduced replication after PNUTS/WDR82 depletion depends on transcription and the phospho-CTD binding protein CDC73.","method":"siRNA knockdown, EdU incorporation, FRAP (RNAPII residence time), replication fork rate assay (DNA fiber), proteasome inhibition, epistasis with CDC73","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (FRAP, fiber assay, proteasome inhibition, genetic epistasis) in a single study","pmids":["33264625"],"is_preprint":false},{"year":2019,"finding":"ATR signaling is increased after depletion of PNUTS-PP1 (the RNAPII-CTD phosphatase); elevated ATR signaling is independent of DNA damage markers or RPA chromatin loading but correlates with R-loop formation; CDC73, which interacts with phospho-CTD RNAPII, is required for high ATR signaling, R-loop formation, and G2 checkpoint activation after PNUTS depletion; ATR, RNAPII, and CDC73 co-immunoprecipitate.","method":"siRNA knockdown, immunofluorescence (γH2AX, pATR), R-loop detection, co-immunoprecipitation, cell cycle analysis","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — co-IP plus genetic epistasis (CDC73 requirement); single lab, multiple readouts","pmids":["30541148"],"is_preprint":false},{"year":2022,"finding":"MYC directly interacts with PNUTS through MYC Homology Box 0 (MB0) and the PNUTS amino-terminal domain (PAD, residues 1–148); NMR solution structure of PAD was determined and the MYC-binding patch characterized; point mutations at the MYC-PNUTS interface weaken interaction in vitro and in vivo and lead to elevated MYC phosphorylation.","method":"NMR spectroscopy (solution structure), in vitro binding assays, site-directed mutagenesis, cellular co-immunoprecipitation","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Strong — NMR structure with mutagenesis validation and in-cell confirmation; multiple orthogonal methods in one study","pmids":["35244724"],"is_preprint":false},{"year":2009,"finding":"PNUTS interacts with LCP1 (an HMG-box protein) through PNUTS's N-terminal region (distinct from the PP1-binding domain) and LCP1's C-terminus; a subpopulation of LCP1 co-localizes with PNUTS in nuclear speckles; PNUTS interaction with LCP1 markedly suppresses LCP1 transcriptional activation activity in a PP1-independent manner.","method":"Yeast two-hybrid, co-immunoprecipitation of deletion constructs, immunofluorescence, GAL4-based transcription reporter assay","journal":"Experimental & molecular medicine","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP domain mapping, co-localization, and functional reporter assay; single lab with two orthogonal approaches","pmids":["19293638"],"is_preprint":false},{"year":2008,"finding":"PNUTS forms a trimeric complex with GABA(C) receptors and PP1 in retinal bipolar cells; PNUTS and PP1 are detected in membrane fractions and co-precipitate with GABA(C) receptor antibodies; GABA(C) receptor co-expression causes PNUTS to shuttle from nucleus to membrane; simultaneous binding of PP1 and GABA(C) receptors to distinct domains of PNUTS was demonstrated.","method":"Co-immunoprecipitation, subcellular fractionation, immunofluorescence (localization shift), domain binding analysis","journal":"Molecular and cellular neurosciences","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP with domain mapping and localization shift; single lab","pmids":["18325784"],"is_preprint":false},{"year":2015,"finding":"PNUTS negatively regulates HIV-1 transcription by inhibiting assembly of the core P-TEFb components cyclin T1 and CDK9; overexpression of PNUTS potently and dose-dependently inhibits HIV-1 replication; miR-34a (upregulated by HIV-1) promotes replication by targeting PNUTS, creating a positive feedback loop.","method":"Overexpression/knockdown, luciferase reporter (HIV-1 LTR), co-immunoprecipitation (P-TEFb assembly), viral replication assay","journal":"The Biochemical journal","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP of P-TEFb components with PNUTS overexpression/knockdown and viral replication readout; single lab","pmids":["26188041"],"is_preprint":false},{"year":2023,"finding":"PNUTS is required for efficient termination of all major RNA Pol II transcript classes, including short ncRNAs and longer protein-coding transcripts; PNUTS is proximal to the Restrictor complex (ZC3H4-WDR82-ARS2) and enables Restrictor function; U1 snRNA shields coding transcripts from Restrictor and PNUTS at hundreds of genes.","method":"siRNA knockdown, ChIRP/ChIP, nascent RNA sequencing (TT-seq/GRO-seq), epistasis experiments","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — genome-wide functional assay with epistasis across transcript classes; multiple orthogonal methods","pmids":["37329883"],"is_preprint":false},{"year":2023,"finding":"Efficient termination at Restrictor-controlled extragenic transcription units requires PNUTS (a negative regulator of SPT5 elongation factor) and Symplekin; PNUTS and Symplekin act synergistically with, but independently from, Restrictor to dampen processive extragenic transcription.","method":"siRNA knockdown, nascent RNA sequencing, epistasis experiments","journal":"Genes & development","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — nascent RNA-seq with genetic epistasis; single lab","pmids":["38092518"],"is_preprint":false},{"year":2024,"finding":"The PNUTS-PP1 complex plays an essential role in transcription pause release in addition to termination; pause release by PNUTS-PP1 is required for almost all RNA Pol II-dependent gene transcription; this function depends on PP1 phosphatase activity and controls phosphorylation of factors required for pause release and elongation.","method":"CRISPR/genetic depletion, ChIP-seq, nascent RNA sequencing, PP1-binding mutant (W401A) analysis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — genome-wide functional analysis with PP1-binding mutant and multiple readouts; defines a new essential function","pmids":["39603239"],"is_preprint":false},{"year":2025,"finding":"PP1/PNUTS co-purifies with the Restrictor complex (ZC3H4/WDR82); PNUTS binds directly to WDR82; AlphaFold predicts a quaternary PPWZ complex; a substrate-trap (inactive PP1H66K fused to PNUTS C-terminus) acts as dominant-negative inhibitor of antisense termination and CTD Ser5 dephosphorylation, demonstrating that phosphatase activity is required for restrictor-mediated termination; CTD Ser5 dephosphorylation by PPWZ promotes termination by increasing Pol II pausing.","method":"Co-immunoprecipitation, AlphaFold structural modeling, substrate-trap dominant-negative expression, NET-seq, ChIP-seq, CTD phospho-state analysis","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — substrate-trap mechanistic dissection combined with structural prediction and genome-wide transcriptomic readout; peer-reviewed","pmids":["40244850"],"is_preprint":false},{"year":2025,"finding":"PNUTS depletion causes CENP-A mislocalization to non-centromeric regions and chromosomal instability (CIN) in a PP1-dependent manner; CENP-C also mislocalizes; kinetochore integrity defects and micronuclei are observed; depletion of the H3.3 chaperone DAXX suppresses CENP-A mislocalization and micronuclei in PNUTS-depleted cells, defining a PNUTS→PP1→DAXX pathway controlling CENP-A deposition.","method":"Genome-wide siRNA screen, siRNA knockdown, immunofluorescence (CENP-A, CENP-C), micronuclei scoring, genetic epistasis (DAXX depletion)","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — genetic epistasis with DAXX plus multiple localization and CIN readouts; single lab","pmids":["40270285"],"is_preprint":false},{"year":2025,"finding":"In Drosophila, Tox4 requires zinc for binding the PNUTS TFIIS N-terminal domain (TND); Tox4 binds TND on a surface distinct from established TND-interacting transcriptional regulators; selective disruption of PNUTS-Tox4 or PNUTS-PP1 interactions impairs normal gene expression and chromosomal dispersal during oogenesis; tox4 is dispensable for viability but essential for fertility with PNUTS-dependent and -independent roles.","method":"Biochemical binding assays, structural analysis, in vivo Drosophila genetics (fertility/oogenesis), transcriptomics, site-directed mutagenesis","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — biochemical, structural, and in vivo genetic approaches in a single study; Drosophila ortholog","pmids":["40347473"],"is_preprint":false},{"year":2025,"finding":"In Drosophila germline, PNUTS and Senataxin associate with the SFiNX complex via Sov to initiate transposon silencing independent of H1 and HP1a heterochromatin; PNUTS mechanistically affects RNA Pol II elongation speed or stalling to induce transcriptional repression of transposable elements prior to heterochromatinization.","method":"Co-immunoprecipitation/mass spectrometry, genetic epistasis (H1, HP1a mutants), RNA Pol II ChIP/elongation assays in Drosophila","journal":"Molecular cell","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP/MS and genetic epistasis in Drosophila; Drosophila ortholog, single study","pmids":["41167190"],"is_preprint":false},{"year":2016,"finding":"The N-terminal domain of PNUTS (PAD) adopts a compact globular fold rich in α-helical content, resembling an extended transcription factor TFIIS (S-II) leucine/tryptophan conserved-motif fold, with a melting temperature of ~49.5°C; this domain mediates interactions with Tox4 and PTEN.","method":"Circular dichroism, NMR spectroscopy, thermal denaturation, bioinformatics","journal":"The protein journal","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — NMR/CD structural characterization of isolated domain; single lab, no mutagenesis or full functional validation in this paper","pmids":["27591855"],"is_preprint":false},{"year":2024,"finding":"PNUTS silencing in endothelial cells causes senescence, reduced angiogenesis, and loss of barrier function; PNUTS-PP1 axis regulates expression of semaphorin 3B (SEMA3B); silencing SEMA3B completely restores barrier function after PNUTS loss; endothelial-specific PNUTS knockout mice (Cdh5-CreERT2;PNUTSfl/fl) develop severe multiorgan failure and vascular leakage within two weeks.","method":"siRNA knockdown, conditional knockout mouse model (Cdh5-CreERT2;PNUTSfl/fl), transcriptomics, barrier function assays, senescence assays, epistasis (SEMA3B rescue)","journal":"Communications biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo conditional KO with defined downstream pathway (SEMA3B epistasis) and multiple orthogonal in vitro readouts","pmids":["38714838"],"is_preprint":false}],"current_model":"PPP1R10/PNUTS is a nuclear PP1-targeting subunit that recruits PP1 to chromatin through direct interaction via an RVXF-related motif (requiring a critical Trp residue), where the PNUTS–PP1 holoenzyme dephosphorylates key substrates including the Rb protein, MYC, and the RNA Pol II CTD (Spt5, Ser5-P) to regulate transcription pause release, elongation speed, termination (including antisense and extragenic ncRNAs via association with the Restrictor/WDR82 complex), chromosome decondensation, DNA damage response/ATR signaling, CENP-A localization, and cell cycle progression; PKA phosphorylation of PNUTS's PP1-binding domain provides a regulatory switch that reduces PP1 association, and PNUTS also functions as a scaffold that sequesters PTEN in the nucleus and bridges PP1 to partners such as GABA(C) receptors, LCP1, and MYC at target gene promoters."},"narrative":{"mechanistic_narrative":"PPP1R10 (PNUTS/p99) is the principal nuclear targeting subunit of protein phosphatase 1 (PP1), forming a stable holoenzyme that directs and constrains PP1 catalytic activity on chromatin to control transcription, cell cycle progression, and genome stability [PMID:9461602, PMID:9450550]. PNUTS binds PP1 through a central ~50-residue domain in a highly extended, intrinsically disordered conformation, using an RVXF-like motif in which a critical tryptophan (W401) replaces the canonical phenylalanine; this contact blocks one of PP1's substrate-binding grooves to inhibit dephosphorylation of substrates such as Rb while leaving the active site available, and the W401A mutation abolishes both binding and the holoenzyme's activities [PMID:9450550, PMID:12574161, PMID:24591642, PMID:15907195]. PKA phosphorylation of the PP1-binding domain reduces PNUTS–PP1 association, providing a regulatory switch [PMID:12574161]. The PNUTS–PP1 complex governs RNA Pol II dynamics genome-wide: it dephosphorylates the elongation factor Spt5 to decelerate Pol II and is required for transcription pause release as well as for termination, where Pol II deceleration downstream of poly(A) sites enables a 'sitting duck torpedo' mechanism [PMID:31677974, PMID:39603239]. Through direct binding to WDR82 and proximity to the Restrictor complex (ZC3H4/WDR82/ARS2) and Symplekin, PNUTS–PP1 dephosphorylates the Pol II CTD (Ser5) to enforce termination of protein-coding, antisense, and extragenic noncoding transcripts [PMID:37329883, PMID:38092518, PMID:40244850]. Beyond transcription, PNUTS–PP1 dephosphorylates and stabilizes MYC at target-gene promoters via a direct MYC MB0–PNUTS PAD interaction, controlling MYC chromatin binding and SCF^FBXW7-mediated turnover [PMID:30158517, PMID:35244724]; promotes chromosome decondensation in telophase [PMID:15907195]; restrains ATR signaling and replication stress in a manner dependent on the phospho-CTD reader CDC73 [PMID:33264625, PMID:30541148]; and controls CENP-A deposition through a PP1→DAXX pathway, maintaining kinetochore integrity and chromosomal stability [PMID:40270285]. PNUTS additionally acts as a PP1-independent scaffold, sequestering PTEN in the nucleus via its C2 domain [PMID:23117887] and bridging PP1 to partners including GABA(C) receptors and the transcriptional regulator LCP1 [PMID:19293638, PMID:18325784]. Endothelial PNUTS is required for vascular integrity in vivo, acting through the PNUTS–PP1 axis to repress SEMA3B [PMID:38714838].","teleology":[{"year":1997,"claim":"Establishing that PPP1R10 is a bona fide PP1 regulatory subunit answered whether this nuclear protein controls phosphatase output, showing it potently inhibits PP1 catalytic activity.","evidence":"Biochemical purification of p99 from HeLa nuclei with in vitro phosphatase assays, identifying an atypical Trp in the PP1-binding motif","pmids":["9450550","9461602"],"confidence":"High","gaps":["Physiological substrates of the holoenzyme not yet defined","Functional consequence of the atypical Trp motif unresolved"]},{"year":2003,"claim":"Mapping the PP1-binding determinant defined how PNUTS docks and is regulated, identifying the essential W residue, PKA-dependent control, and a separable nucleic-acid-binding C-terminus.","evidence":"Truncation/mutagenesis with GST pulldown, in vitro phosphatase and PKA kinase assays, and RNA/ssDNA binding in 293T cells","pmids":["12574161"],"confidence":"High","gaps":["In vivo relevance of RNA binding not established","Which substrates are gated by PKA phosphorylation unknown"]},{"year":2014,"claim":"Atomic-resolution structure explained the inhibitory mechanism, showing PNUTS binds PP1 in an extended manner and occludes the arginine substrate groove rather than the active site.","evidence":"NMR and X-ray crystallography of the PNUTS–PP1 complex with biochemical and mutagenesis validation against Rb dephosphorylation","pmids":["24591642"],"confidence":"High","gaps":["Structure of full-length, intrinsically disordered PNUTS not determined","How substrate selectivity is achieved in cells not resolved"]},{"year":2002,"claim":"Linking PNUTS to Rb dephosphorylation answered which cell-cycle substrate the holoenzyme gates, showing PNUTS inhibits PP1 toward pRb and dissociates under hypoxia.","evidence":"In vitro pRb-directed phosphatase assay with GST-PNUTS and hypoxia treatment of cells","pmids":["12270115"],"confidence":"Medium","gaps":["Mechanism coupling hypoxia to PNUTS–PP1 dissociation unknown","Cellular hypoxia correlate not mechanistically tied to phosphatase change"]},{"year":2005,"claim":"Connecting PNUTS to mitotic exit showed the holoenzyme drives chromatin decondensation, establishing a structural role for PP1 targeting at telophase.","evidence":"Subcellular fractionation, in vitro chromosome decondensation assays in defined buffer, and W401A mutagenesis","pmids":["15907195"],"confidence":"High","gaps":["Direct chromatin substrate dephosphorylated during decondensation not identified","Recruitment mechanism to reforming nuclei unclear"]},{"year":2008,"claim":"Genetic epistasis defined the consequence of losing PNUTS in cancer cells, showing PNUTS loss unleashes PP1 on Rb to trigger E2F1 release and caspase-8 apoptosis selectively in Rb-expressing cells.","evidence":"siRNA knockdown with Rb-null vs Rb-expressing cell panel, Rb-phosphatase and apoptosis assays","pmids":["18360108"],"confidence":"Medium","gaps":["Single lab","Why normal cells are spared not mechanistically resolved"]},{"year":2008,"claim":"Discovery of a PNUTS–PP1–GABA(C) receptor complex showed PNUTS can act as a membrane-targeting scaffold outside the nucleus.","evidence":"Co-IP, subcellular fractionation, and localization shift upon receptor co-expression in retinal bipolar cells","pmids":["18325784"],"confidence":"Medium","gaps":["Functional output of receptor-associated PP1 not defined","Single lab; physiological context limited"]},{"year":2009,"claim":"Identifying the PNUTS–LCP1 interaction showed PNUTS has a PP1-independent transcriptional-repression function distinct from its phosphatase-targeting role.","evidence":"Yeast two-hybrid, Co-IP domain mapping, nuclear speckle co-localization, and GAL4 reporter assays","pmids":["19293638"],"confidence":"Medium","gaps":["Endogenous target genes of LCP1 repression unknown","Single lab"]},{"year":2010,"claim":"Implicating PNUTS in the DNA damage response showed it restrains G2 checkpoint activation and supports repair, recruiting transiently to damage sites.","evidence":"siRNA knockdown, live-cell imaging of PNUTS-EGFP recruitment, cell-cycle flow cytometry, repair foci, and clonogenic survival after IR","pmids":["20890310"],"confidence":"High","gaps":["Substrate dephosphorylated at damage sites not identified","Whether checkpoint role is PP1-dependent not directly tested here"]},{"year":2012,"claim":"Identifying PTEN sequestration showed PNUTS scaffolds a tumor suppressor in the nucleus, defining a PP1-independent function via the PTEN C2 domain.","evidence":"Co-IP, GST pulldown domain mapping, siRNA knockdown with PTEN-dependent viability/apoptosis readouts","pmids":["23117887"],"confidence":"Medium","gaps":["Regulation of PTEN nuclear/cytoplasmic shuttling by PNUTS unclear","Single lab"]},{"year":2015,"claim":"Linking PNUTS to HIV-1 transcription showed it negatively regulates P-TEFb assembly, embedding it in a viral miR-34a feedback loop.","evidence":"Overexpression/knockdown, HIV-1 LTR luciferase reporter, Co-IP of cyclin T1/CDK9, and replication assays","pmids":["26188041"],"confidence":"Medium","gaps":["Whether PP1 activity is required for P-TEFb inhibition not resolved","Single lab"]},{"year":2018,"claim":"Defining the MYC connection showed PNUTS–PP1 dephosphorylates and stabilizes MYC at promoters, controlling MYC chromatin binding and FBXW7-mediated turnover.","evidence":"BioID-MS, Co-IP, ChIP, RNAi, pharmacological PP1 inhibition, and phospho-site mass spectrometry across multiple cell types","pmids":["30158517"],"confidence":"High","gaps":["Direct PNUTS-PP1 MYC phospho-sites not all mapped to function in this study","Interface of MYC contact not yet structurally defined here"]},{"year":2018,"claim":"Linking PNUTS to mitotic fidelity showed it associates with Aurora kinases/kinetochore components and is required for CPC regulation and spindle checkpoint signaling.","evidence":"siRNA knockdown, Co-IP/MS, kinetochore immunofluorescence, kinase assays, and live-cell imaging","pmids":["30190438"],"confidence":"Medium","gaps":["Whether PNUTS-PP1 phosphatase activity drives Aurora regulation not separated","Single lab"]},{"year":2019,"claim":"Genome-wide elongation profiling established that PNUTS-PP1 decelerates Pol II via Spt5 dephosphorylation, defining a 'sitting duck torpedo' termination model dependent on poly(A) recognition.","evidence":"TT-seq, ChIP-seq, W401A mutagenesis, and phospho-Spt5 analysis with in vivo elongation rate measurement","pmids":["31677974"],"confidence":"High","gaps":["How poly(A) site recognition is coupled to PP1 recruitment unresolved","Full set of CTD/elongation substrates not enumerated"]},{"year":2019,"claim":"Connecting PNUTS-PP1 to replication stress showed that loss elevates ATR signaling via R-loops in a CDC73-dependent manner, independent of canonical damage markers.","evidence":"siRNA knockdown, pATR/γH2AX immunofluorescence, R-loop detection, Co-IP of ATR/RNAPII/CDC73, and cell-cycle analysis","pmids":["30541148"],"confidence":"Medium","gaps":["Mechanism by which CDC73 promotes R-loops not defined","Single lab"]},{"year":2020,"claim":"Showing PNUTS-PP1 suppresses replication stress via CTD dephosphorylation established that it limits RNAPII chromatin residence and promotes proteasomal RNAPII turnover with WDR82.","evidence":"siRNA knockdown, EdU incorporation, FRAP of RNAPII, DNA fiber assays, proteasome inhibition, and CDC73 epistasis","pmids":["33264625"],"confidence":"High","gaps":["Direct trigger for proteasomal RNAPII degradation unclear","How transcription-replication conflicts are resolved mechanistically open"]},{"year":2022,"claim":"Structural definition of the MYC–PNUTS interface answered how PNUTS engages MYC, showing MYC MB0 binds the PNUTS PAD and that interface mutations elevate MYC phosphorylation.","evidence":"NMR solution structure of PAD, in vitro binding, mutagenesis, and cellular Co-IP","pmids":["35244724"],"confidence":"High","gaps":["How PP1 catalysis is positioned on MYC by this interface not shown","In vivo tumor relevance of interface mutations untested here"]},{"year":2023,"claim":"Connecting PNUTS to the Restrictor pathway showed it enables termination of all major Pol II transcript classes, with U1 snRNA shielding coding transcripts.","evidence":"siRNA knockdown, ChIRP/ChIP, and nascent RNA sequencing with epistasis","pmids":["37329883"],"confidence":"High","gaps":["Molecular basis of PNUTS–Restrictor proximity not structurally defined here","How U1 antagonizes PNUTS function unresolved"]},{"year":2023,"claim":"Defining PNUTS–Symplekin cooperation showed PNUTS dampens processive extragenic transcription synergistically with, but independently from, Restrictor.","evidence":"siRNA knockdown and nascent RNA sequencing with genetic epistasis","pmids":["38092518"],"confidence":"Medium","gaps":["Mechanistic basis of Symplekin synergy unclear","Single lab"]},{"year":2024,"claim":"Establishing PNUTS-PP1 in pause release showed it is required for nearly all Pol II-dependent transcription, dependent on PP1 catalytic activity.","evidence":"CRISPR/genetic depletion, ChIP-seq, nascent RNA sequencing, and W401A mutant analysis","pmids":["39603239"],"confidence":"High","gaps":["Specific pause-release substrate phospho-sites not fully mapped","How pause-release and termination roles are temporally coordinated open"]},{"year":2024,"claim":"An endothelial conditional knockout established an in vivo physiological role, showing PNUTS-PP1 maintains vascular barrier function by repressing SEMA3B.","evidence":"Cdh5-CreERT2;PNUTSfl/fl mice, siRNA knockdown, transcriptomics, barrier/senescence assays, and SEMA3B rescue","pmids":["38714838"],"confidence":"High","gaps":["How PNUTS-PP1 controls SEMA3B transcription mechanistically unclear","Tissue specificity of the phenotype not fully explained"]},{"year":2025,"claim":"Substrate-trap dissection of the PPWZ complex showed PNUTS binds WDR82 directly and that PP1 catalytic activity dephosphorylating CTD Ser5 is required for Restrictor-mediated termination.","evidence":"Co-IP, AlphaFold modeling, dominant-negative PP1H66K substrate trap, NET-seq, ChIP-seq, and CTD phospho-state analysis","pmids":["40244850"],"confidence":"High","gaps":["Experimental structure of the PPWZ quaternary complex lacking","How CTD Ser5 dephosphorylation increases pausing mechanistically open"]},{"year":2025,"claim":"Defining a PNUTS→PP1→DAXX axis showed PNUTS controls CENP-A deposition and chromosomal stability, with DAXX loss suppressing CENP-A mislocalization.","evidence":"Genome-wide siRNA screen, knockdown, CENP-A/CENP-C immunofluorescence, micronuclei scoring, and DAXX epistasis","pmids":["40270285"],"confidence":"Medium","gaps":["Direct PP1 substrate in the DAXX pathway not identified","Single lab"]},{"year":2025,"claim":"Drosophila studies extended PNUTS function to germline biology, showing zinc-dependent Tox4 binding to the PNUTS TND and roles in transposon silencing via SFiNX/Senataxin.","evidence":"Biochemical/structural binding assays and in vivo Drosophila genetics, transcriptomics, and Pol II ChIP","pmids":["40347473","41167190"],"confidence":"Medium","gaps":["Conservation of these roles in mammals untested","Drosophila ortholog; direct PP1 substrates in transposon silencing unknown"]},{"year":null,"claim":"How the multiple PNUTS-PP1 chromatin functions (pause release, termination, CTD/Spt5 dephosphorylation, CENP-A deposition, MYC stabilization, DNA damage response) are spatially and temporally coordinated by a single targeting subunit remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying model for substrate selection in vivo","Structure of full-length PNUTS holoenzyme on chromatin lacking","Direct dephosphorylation substrate maps incomplete for most pathways"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,2,3]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[3,9,10,20,21]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[8,15,16,21]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[2]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[2]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[15]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,1]},{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[1,15]},{"term_id":"GO:0005730","term_label":"nucleolus","supporting_discovery_ids":[1]},{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[0,4]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[16]}],"pathway":[{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[10,18,20,21]},{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[18,19,21]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[4,6,7,11]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[7,12,13]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[8,9]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[6,8]}],"complexes":["PNUTS-PP1 holoenzyme","Restrictor complex (ZC3H4/WDR82/ARS2)","PPWZ complex (PP1-PNUTS-WDR82-ZC3H4)"],"partners":["PPP1CA","WDR82","MYC","PTEN","LCP1","CDC73","TOX4","ZC3H4"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q96QC0","full_name":"Serine/threonine-protein phosphatase 1 regulatory subunit 10","aliases":["MHC class I region proline-rich protein CAT53","PP1-binding protein of 114 kDa","Phosphatase 1 nuclear targeting subunit","p99"],"length_aa":940,"mass_kda":99.1,"function":"Substrate-recognition component of the PNUTS-PP1 protein phosphatase complex, a protein phosphatase 1 (PP1) complex that promotes RNA polymerase II transcription pause-release, allowing transcription elongation (PubMed:39603239, PubMed:39603240). Promoter-proximal pausing by RNA polymerase II is a transcription halt following transcription initiation but prior to elongation, which acts as a checkpoint to control that transcripts are favorably configured for transcriptional elongation (PubMed:39603239, PubMed:39603240). The PNUTS-PP1 complex mediates the release of RNA polymerase II from promoter-proximal region of genes by catalyzing dephosphorylation of proteins involved in transcription, such as AFF4, CDK9, MEPCE, INTS12, NCBP1, POLR2M/GDOWN1 and SUPT6H (PubMed:39603239, PubMed:39603240). The PNUTS-PP1 complex also regulates RNA polymerase II transcription termination by mediating dephosphorylation of SUPT5H in termination zones downstream of poly(A) sites, thereby promoting deceleration of RNA polymerase II transcription (PubMed:31677974). PNUTS-PP1 complex is also involved in the response to replication stress by mediating dephosphorylation of POLR2A at 'Ser-5' of the CTD, promoting RNA polymerase II degradation (PubMed:33264625). The PNUTS-PP1 complex also plays a role in the control of chromatin structure and cell cycle progression during the transition from mitosis into interphase (By similarity). PNUTS-PP1 complex mediates dephosphorylation of MYC, promoting MYC stability by preventing MYC ubiquitination by the SCF(FBXW7) complex (PubMed:30158517). In addition to acts as a substrate-recognition component, PPP1R10/PNUTS also acts as a nuclear targeting subunit for the PNUTS-PP1 complex (PubMed:9450550). In some context, PPP1R10/PNUTS also acts as an inhibitor of protein phosphatase 1 (PP1) activity by preventing access to substrates, such as RB (PubMed:18360108)","subcellular_location":"Nucleus; Chromosome","url":"https://www.uniprot.org/uniprotkb/Q96QC0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/PPP1R10","classification":"Common Essential","n_dependent_lines":1195,"n_total_lines":1208,"dependency_fraction":0.9892384105960265},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CPSF6","stoichiometry":0.2},{"gene":"HIST2H2BE","stoichiometry":0.2},{"gene":"RBM14","stoichiometry":0.2},{"gene":"RBM39","stoichiometry":0.2},{"gene":"SNRPA","stoichiometry":0.2},{"gene":"SNRPB","stoichiometry":0.2},{"gene":"SNRPC","stoichiometry":0.2},{"gene":"SNRPF","stoichiometry":0.2},{"gene":"SSRP1","stoichiometry":0.2},{"gene":"SUPT5H","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/PPP1R10","total_profiled":1310},"omim":[{"mim_id":"614032","title":"TOX HIGH MOBILITY GROUP BOX FAMILY MEMBER 4; TOX4","url":"https://www.omim.org/entry/614032"},{"mim_id":"611172","title":"MICRO RNA 34A; MIR34A","url":"https://www.omim.org/entry/611172"},{"mim_id":"611059","title":"WD REPEAT-CONTAINING PROTEIN 82; WDR82","url":"https://www.omim.org/entry/611059"},{"mim_id":"603771","title":"PROTEIN PHOSPHATASE 1, REGULATORY SUBUNIT 10; PPP1R10","url":"https://www.omim.org/entry/603771"},{"mim_id":"176875","title":"PROTEIN PHOSPHATASE 1, CATALYTIC SUBUNIT, ALPHA ISOFORM; PPP1CA","url":"https://www.omim.org/entry/176875"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Nucleoplasm","reliability":"Enhanced"},{"location":"Nuclear bodies","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in many","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PPP1R10"},"hgnc":{"alias_symbol":["PNUTS","FB19","CAT53","p99"],"prev_symbol":[]},"alphafold":{"accession":"Q96QC0","domains":[{"cath_id":"1.20.930","chopping":"9-147","consensus_level":"medium","plddt":95.6547,"start":9,"end":147}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96QC0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96QC0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96QC0-F1-predicted_aligned_error_v6.png","plddt_mean":56.91},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PPP1R10","jax_strain_url":"https://www.jax.org/strain/search?query=PPP1R10"},"sequence":{"accession":"Q96QC0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96QC0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96QC0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96QC0"}},"corpus_meta":[{"pmid":"28825698","id":"PMC_28825698","title":"A regulated PNUTS mRNA to lncRNA splice switch mediates EMT and tumour progression.","date":"2017","source":"Nature cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/28825698","citation_count":272,"is_preprint":false},{"pmid":"8248237","id":"PMC_8248237","title":"Evolution of an enzyme activity: crystallographic structure at 2-A resolution of cephalosporinase from the ampC gene of Enterobacter cloacae P99 and comparison with a class A penicillinase.","date":"1993","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/8248237","citation_count":193,"is_preprint":false},{"pmid":"31677974","id":"PMC_31677974","title":"Control of RNA Pol II Speed by PNUTS-PP1 and Spt5 Dephosphorylation Facilitates Termination by a \"Sitting Duck Torpedo\" Mechanism.","date":"2019","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/31677974","citation_count":176,"is_preprint":false},{"pmid":"8204611","id":"PMC_8204611","title":"Crystallographic structure of a phosphonate derivative of the Enterobacter cloacae P99 cephalosporinase: mechanistic interpretation of a beta-lactamase transition-state analog.","date":"1994","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/8204611","citation_count":146,"is_preprint":false},{"pmid":"9461602","id":"PMC_9461602","title":"Isolation and characterization of PNUTS, a putative protein phosphatase 1 nuclear targeting subunit.","date":"1998","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9461602","citation_count":137,"is_preprint":false},{"pmid":"20921316","id":"PMC_20921316","title":"Mechanistic studies of the inactivation of TEM-1 and P99 by NXL104, a novel non-beta-lactam beta-lactamase inhibitor.","date":"2010","source":"Antimicrobial agents and chemotherapy","url":"https://pubmed.ncbi.nlm.nih.gov/20921316","citation_count":122,"is_preprint":false},{"pmid":"24591642","id":"PMC_24591642","title":"Understanding the antagonism of retinoblastoma protein dephosphorylation by PNUTS provides insights into the PP1 regulatory code.","date":"2014","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/24591642","citation_count":105,"is_preprint":false},{"pmid":"3027046","id":"PMC_3027046","title":"Common mechanism of ampC beta-lactamase induction in enterobacteria: regulation of the cloned Enterobacter cloacae P99 beta-lactamase gene.","date":"1987","source":"Journal of bacteriology","url":"https://pubmed.ncbi.nlm.nih.gov/3027046","citation_count":92,"is_preprint":false},{"pmid":"9450550","id":"PMC_9450550","title":"Purification and characterisation of p99, a nuclear modulator of protein phosphatase 1 activity.","date":"1997","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/9450550","citation_count":78,"is_preprint":false},{"pmid":"12574161","id":"PMC_12574161","title":"PNUTS, a protein phosphatase 1 (PP1) nuclear targeting subunit. 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P99.","date":"2005","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15895997","citation_count":10,"is_preprint":false},{"pmid":"30244253","id":"PMC_30244253","title":"Downregulation of MicroRNA-4463 Attenuates High-Glucose- and Hypoxia-Induced Endothelial Cell Injury by Targeting PNUTS.","date":"2018","source":"Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/30244253","citation_count":9,"is_preprint":false},{"pmid":"30863088","id":"PMC_30863088","title":"PNUTS mediates ionizing radiation-induced CNE-2 nasopharyngeal carcinoma cell migration, invasion, and epithelial-mesenchymal transition via the PI3K/AKT signaling pathway.","date":"2019","source":"OncoTargets and therapy","url":"https://pubmed.ncbi.nlm.nih.gov/30863088","citation_count":8,"is_preprint":false},{"pmid":"35139713","id":"PMC_35139713","title":"Alternatively-spliced lncRNA-PNUTS promotes HCC cell EMT via regulating ZEB1 expression.","date":"2022","source":"Tumori","url":"https://pubmed.ncbi.nlm.nih.gov/35139713","citation_count":7,"is_preprint":false},{"pmid":"30391100","id":"PMC_30391100","title":"Activation of human macrophage sodium channels regulates RNA processing to increase expression of the DNA repair protein PPP1R10.","date":"2018","source":"Immunobiology","url":"https://pubmed.ncbi.nlm.nih.gov/30391100","citation_count":7,"is_preprint":false},{"pmid":"27591855","id":"PMC_27591855","title":"Biophysical Analysis of the N-Terminal Domain from the Human Protein Phosphatase 1 Nuclear Targeting Subunit PNUTS Suggests an Extended Transcription Factor TFIIS-Like Fold.","date":"2016","source":"The protein journal","url":"https://pubmed.ncbi.nlm.nih.gov/27591855","citation_count":7,"is_preprint":false},{"pmid":"18029418","id":"PMC_18029418","title":"Saturation mutagenesis of Asn152 reveals a substrate selectivity switch in P99 cephalosporinase.","date":"2007","source":"Protein science : a publication of the Protein Society","url":"https://pubmed.ncbi.nlm.nih.gov/18029418","citation_count":7,"is_preprint":false},{"pmid":"9784381","id":"PMC_9784381","title":"Cloning of a new gene (FB19) within HLA class I region.","date":"1998","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/9784381","citation_count":6,"is_preprint":false},{"pmid":"19437416","id":"PMC_19437416","title":"Developing bifunctional beta-lactamase molecules with built-in target-recognizing module for prodrug therapy: identification of Enterobacter Cloacae P99 cephalosporinase loops suitable for randomization and phage-display selection.","date":"2009","source":"Journal of molecular recognition : JMR","url":"https://pubmed.ncbi.nlm.nih.gov/19437416","citation_count":5,"is_preprint":false},{"pmid":"22948919","id":"PMC_22948919","title":"Structural analysis of the Asn152Gly mutant of P99 cephalosporinase.","date":"2012","source":"Acta crystallographica. Section D, Biological crystallography","url":"https://pubmed.ncbi.nlm.nih.gov/22948919","citation_count":5,"is_preprint":false},{"pmid":"40244850","id":"PMC_40244850","title":"PP1/PNUTS phosphatase binds the restrictor complex and stimulates RNA Pol II transcription termination.","date":"2025","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/40244850","citation_count":4,"is_preprint":false},{"pmid":"17638579","id":"PMC_17638579","title":"Overexpression of the recombinant Enterobacter cloacae P99 AmpC beta-lactamase and its mutants based on a phi105 prophage system in Bacillus subtilis.","date":"2007","source":"Protein expression and purification","url":"https://pubmed.ncbi.nlm.nih.gov/17638579","citation_count":4,"is_preprint":false},{"pmid":"40103229","id":"PMC_40103229","title":"Overlapping and distinct functions of SPT6, PNUTS, and PCF11 in regulating transcription termination.","date":"2025","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/40103229","citation_count":3,"is_preprint":false},{"pmid":"37926279","id":"PMC_37926279","title":"Leishmania PNUTS discriminates between PP1 catalytic subunits through an RVxF-ΦΦ-F motif and polymorphisms in the PP1 C-tail and catalytic domain.","date":"2023","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/37926279","citation_count":3,"is_preprint":false},{"pmid":"2475102","id":"PMC_2475102","title":"Purification of a class C A-type beta-lactamase from a derepressed strain of Enterobacter cloacae. Comparison of the wild-type and mutant enzyme with those from strains P99, 208 and GN7471.","date":"1989","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/2475102","citation_count":3,"is_preprint":false},{"pmid":"38714838","id":"PMC_38714838","title":"Aging-regulated PNUTS maintains endothelial barrier function via SEMA3B suppression.","date":"2024","source":"Communications biology","url":"https://pubmed.ncbi.nlm.nih.gov/38714838","citation_count":2,"is_preprint":false},{"pmid":"41167190","id":"PMC_41167190","title":"The Piwi-piRNA complex initiates transposon silencing via transcription termination factors PNUTS and Senataxin.","date":"2025","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/41167190","citation_count":2,"is_preprint":false},{"pmid":"17192008","id":"PMC_17192008","title":"Molecular modeling of Henry-Michaelis and acyl-enzyme complexes between imipenem and Enterobacter cloacae P99 beta-lactamase.","date":"2005","source":"Chemistry & biodiversity","url":"https://pubmed.ncbi.nlm.nih.gov/17192008","citation_count":2,"is_preprint":false},{"pmid":"3266632","id":"PMC_3266632","title":"Large-scale purification of the chromosomal beta-lactamase from Enterobacter cloacae P99.","date":"1988","source":"Journal of chromatography","url":"https://pubmed.ncbi.nlm.nih.gov/3266632","citation_count":2,"is_preprint":false},{"pmid":"40270285","id":"PMC_40270285","title":"Protein Phosphatase 1 Regulatory Subunit PNUTS Prevents CENP-A Mislocalization and Chromosomal Instability.","date":"2025","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/40270285","citation_count":1,"is_preprint":false},{"pmid":"37790576","id":"PMC_37790576","title":"Leishmania PNUTS discriminates between PP1 catalytic subunits through a RVxF-ΦΦ-F motif and polymorphisms in the PP1 C-tail and catalytic domain.","date":"2023","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/37790576","citation_count":1,"is_preprint":false},{"pmid":"40347473","id":"PMC_40347473","title":"PNUTS:PP1 recruitment to Tox4 regulates chromosomal dispersal in Drosophila germline development.","date":"2025","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/40347473","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.01.13.632704","title":"Asparagine endopeptidase promotes radioresistance in breast cancer through ATR pathway modulation","date":"2025-01-15","source":"bioRxiv","url":"https://doi.org/10.1101/2025.01.13.632704","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.07.12.603302","title":"PP1 PNUTS binds the “restrictor” and dephosphorylates RNA pol II CTD Ser5 to stimulate transcription termination","date":"2024-07-13","source":"bioRxiv","url":"https://doi.org/10.1101/2024.07.12.603302","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":36669,"output_tokens":7259,"usd":0.109446,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":16433,"output_tokens":7440,"usd":0.134082,"stage2_stop_reason":"end_turn"},"total_usd":0.243528,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1998,\n      \"finding\": \"PNUTS (PPP1R10) was identified as a PP1-interacting protein that forms a stable complex with PP1 in mammalian cell lysates, potently modulates PP1 catalytic activity toward exogenous substrates in vitro, and exhibits discrete nuclear compartmentalization with co-localization with chromatin during mitosis.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation from mammalian cell lysates, in vitro phosphatase activity assay, immunofluorescence\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, in vitro activity assay, and localization by immunofluorescence; independently replicated by Kreivi et al. (PMID:9450550) same year\",\n      \"pmids\": [\"9461602\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"p99 (PPP1R10) was purified as a PP1 regulatory subunit from HeLa cell nuclei; recombinant p99 suppresses PP1 phosphorylase phosphatase activity by >90%; the PP1-binding motif contains an unusual tryptophan in place of the canonical phenylalanine; p99 shows punctate nucleoplasmic staining with nucleolar accumulations.\",\n      \"method\": \"Biochemical purification from HeLa nuclei, in vitro phosphatase activity assay, immunofluorescence, cDNA cloning\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — in vitro reconstitution of PP1 inhibition, replicated by Allen et al. (PMID:9461602)\",\n      \"pmids\": [\"9450550\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"A 50-amino acid central domain of PNUTS mediates high-affinity PP1 binding and inhibition of PP1 activity; the critical tryptophan residue within the RVXF-like motif is essential (W→A mutation abolishes PP1 binding and inhibition); protein kinase A phosphorylates this PP1-binding domain and substantially reduces PNUTS–PP1 interaction in vitro and in intact cells upon PKA stimulation; a C-terminal region containing RGG motifs and His/Gly-rich repeats binds mRNA and ssDNA with selectivity for poly(A) and poly(G); a PNUTS–PP1 complex can be isolated via RNA-conjugated beads.\",\n      \"method\": \"GST pulldown, FLAG-tagged protein expression in 293T cells, in vitro phosphatase assay, in vitro kinase assay (PKA), in vitro RNA binding, site-directed mutagenesis, truncation analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal methods (mutagenesis, in vitro assays, intact-cell PKA stimulation) in a single rigorous study\",\n      \"pmids\": [\"12574161\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"PNUTS is intrinsically disordered in its free form and binds PP1 in a highly extended manner; PNUTS blocks one of PP1's substrate-binding grooves (the 'arginine site') while leaving the active site accessible, thereby inhibiting PP1-mediated dephosphorylation of Rb by blocking Rb's binding site on PP1; unique PP1-binding motifs defined by the PNUTS–PP1 structure allow prediction of how >25% of known PP1 regulators bind PP1.\",\n      \"method\": \"NMR structure determination, X-ray crystallography, biochemical binding assays, mutagenesis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — atomic-resolution structure with functional validation; multiple orthogonal structural and biochemical methods\",\n      \"pmids\": [\"24591642\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"PNUTS co-fractionates with micrococcal nuclease-soluble chromatin in interphase and is targeted to reforming nuclei in telophase concomitant with chromatin decondensation; recombinant PNUTS(309-691) accelerates decondensation of prometaphase chromosomes in vitro in a manner requiring the RVXF PP1-binding motif (W401A mutation abolishes activity); PNUTS promotes decondensation via the PNUTS:PP1 holoenzyme in a defined buffer system with exogenous PP1.\",\n      \"method\": \"Subcellular fractionation, in vitro chromosome decondensation assay (cytosolic extract and defined buffer system), immunofluorescence, site-directed mutagenesis (W401A)\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — in vitro reconstitution with mutagenesis validation and two independent assay systems in one study\",\n      \"pmids\": [\"15907195\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"PNUTS inhibits PP1c activity toward pRb; GST-PNUTS fusion protein inhibits pRb-directed PP1c activity using PP1c from cell lysates, GST-PP1c, or purified PP1c; PNUTS dissociates from PP1c under mildly hypoxic conditions coincident with increased PP1c activity toward pRb.\",\n      \"method\": \"In vitro pRb-directed phosphatase assay, GST pulldown, hypoxia treatment of cells\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro phosphatase assay with purified components and cell-based correlate; single lab, two orthogonal approaches\",\n      \"pmids\": [\"12270115\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Reduced expression of PNUTS in cancer cells increases PP1 activity toward Rb, leading to Rb dephosphorylation, dissociation of E2F1 from Rb, and caspase-8-dependent apoptosis; this effect requires Rb (no effect in Rb-null cells) and is p53-independent; normal cells are not affected by PNUTS knockdown.\",\n      \"method\": \"siRNA knockdown, cell viability assay, apoptosis assay, Rb-phosphatase activity assay, cell line panel (Rb-null vs. Rb-expressing)\",\n      \"journal\": \"Cancer biology & therapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — defined genetic epistasis (Rb-null rescue), phosphatase activity assay, and phenotypic readout; single lab\",\n      \"pmids\": [\"18360108\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"PNUTS depletion by siRNA activates a G2 checkpoint in unperturbed cells and prolongs G2 arrest and Chk1 activation after ionizing-radiation-induced DNA damage; overexpression of PNUTS-EGFP, which rapidly and transiently localizes to DNA damage sites, inhibits G2 arrest; PNUTS depletion causes prolonged γH2AX, 53BP1, RPA, and Rad51 foci and decreased clonogenic survival after irradiation.\",\n      \"method\": \"siRNA knockdown, live-cell imaging (PNUTS-EGFP recruitment to damage sites), flow cytometry (cell cycle), immunofluorescence (γH2AX, 53BP1, RPA, Rad51), clonogenic survival assay\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal readouts (live imaging, cell cycle analysis, DNA repair foci, survival) with gain- and loss-of-function in same study\",\n      \"pmids\": [\"20890310\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PNUTS directly interacts with the C2 (lipid-binding) domain of PTEN and sequesters PTEN in the nucleus; depletion of PNUTS leads to increased apoptosis and reduced proliferation in a PTEN-dependent manner.\",\n      \"method\": \"Co-immunoprecipitation, GST pulldown (domain mapping), siRNA knockdown, cell viability and apoptosis assays\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP plus domain-mapping pulldown, PTEN-dependent epistasis; single lab\",\n      \"pmids\": [\"23117887\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Endogenous MYC and PNUTS interact across multiple cell types and co-occupy MYC target gene promoters; PP1/PNUTS dephosphorylates MYC at multiple serine/threonine residues; inhibiting PP1 causes MYC hyperphosphorylation, proteasomal degradation via SCFFBXW7, and loss of MYC chromatin binding while retaining MAX interaction; rescue requires specifically PP1, not other phosphatases.\",\n      \"method\": \"BioID mass spectrometry, co-immunoprecipitation, ChIP, RNAi knockdown, pharmacological PP1 inhibition, phospho-site mass spectrometry\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (BioID, Co-IP, ChIP, mass spec, genetic and pharmacological perturbations) in one rigorous study\",\n      \"pmids\": [\"30158517\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PNUTS-PP1 is a negative regulator of RNA Pol II elongation rate; the PNUTS W401A mutation (disrupting PP1 binding) causes genome-wide acceleration of transcription associated with hyper-phosphorylation of the Spt5 elongation factor; Pol II decelerates immediately downstream of poly(A) sites, correlating with Spt5 dephosphorylation requiring poly(A) site recognition and the PNUTS-PP1 complex; PNUTS-PP1-dependent Pol II deceleration is required for transcription termination ('sitting duck torpedo' mechanism).\",\n      \"method\": \"TT-seq (transient transcriptome sequencing), ChIP-seq, site-directed mutagenesis (W401A), in vivo elongation rate measurement, phospho-Spt5 analysis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genome-wide functional assay combined with mutagenesis and mechanistic epistasis, defining a new termination model\",\n      \"pmids\": [\"31677974\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"PNUTS expression is elevated in mitosis; PNUTS depletion partially blocks mitotic entry and causes chromosome mis-segregation; Aurora A/B kinase complexes and kinetochore components are PNUTS-associated proteins; PNUTS depletion suppresses Aurora A/B activation and disrupts chromosomal passenger complex (CPC) spatiotemporal regulation; PNUTS dynamically localizes to kinetochores and is required for spindle assembly checkpoint activation.\",\n      \"method\": \"siRNA knockdown, co-immunoprecipitation/MS, immunofluorescence (kinetochore localization), kinase activity assay, live-cell imaging\",\n      \"journal\": \"Molecular cancer research : MCR\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP/MS with functional knockdown phenotypes and localization; single lab\",\n      \"pmids\": [\"30190438\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PNUTS-PP1 promotes RNAPII CTD dephosphorylation and suppresses replication stress; PNUTS depletion causes lower EdU uptake, S-phase accumulation, and slower replication fork rates; RNAPII has a longer chromatin residence time after PNUTS or WDR82 depletion; PNUTS and WDR82 promote proteasome-dependent degradation of RNAPII on chromatin; reduced replication after PNUTS/WDR82 depletion depends on transcription and the phospho-CTD binding protein CDC73.\",\n      \"method\": \"siRNA knockdown, EdU incorporation, FRAP (RNAPII residence time), replication fork rate assay (DNA fiber), proteasome inhibition, epistasis with CDC73\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (FRAP, fiber assay, proteasome inhibition, genetic epistasis) in a single study\",\n      \"pmids\": [\"33264625\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"ATR signaling is increased after depletion of PNUTS-PP1 (the RNAPII-CTD phosphatase); elevated ATR signaling is independent of DNA damage markers or RPA chromatin loading but correlates with R-loop formation; CDC73, which interacts with phospho-CTD RNAPII, is required for high ATR signaling, R-loop formation, and G2 checkpoint activation after PNUTS depletion; ATR, RNAPII, and CDC73 co-immunoprecipitate.\",\n      \"method\": \"siRNA knockdown, immunofluorescence (γH2AX, pATR), R-loop detection, co-immunoprecipitation, cell cycle analysis\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — co-IP plus genetic epistasis (CDC73 requirement); single lab, multiple readouts\",\n      \"pmids\": [\"30541148\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"MYC directly interacts with PNUTS through MYC Homology Box 0 (MB0) and the PNUTS amino-terminal domain (PAD, residues 1–148); NMR solution structure of PAD was determined and the MYC-binding patch characterized; point mutations at the MYC-PNUTS interface weaken interaction in vitro and in vivo and lead to elevated MYC phosphorylation.\",\n      \"method\": \"NMR spectroscopy (solution structure), in vitro binding assays, site-directed mutagenesis, cellular co-immunoprecipitation\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — NMR structure with mutagenesis validation and in-cell confirmation; multiple orthogonal methods in one study\",\n      \"pmids\": [\"35244724\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"PNUTS interacts with LCP1 (an HMG-box protein) through PNUTS's N-terminal region (distinct from the PP1-binding domain) and LCP1's C-terminus; a subpopulation of LCP1 co-localizes with PNUTS in nuclear speckles; PNUTS interaction with LCP1 markedly suppresses LCP1 transcriptional activation activity in a PP1-independent manner.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation of deletion constructs, immunofluorescence, GAL4-based transcription reporter assay\",\n      \"journal\": \"Experimental & molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP domain mapping, co-localization, and functional reporter assay; single lab with two orthogonal approaches\",\n      \"pmids\": [\"19293638\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PNUTS forms a trimeric complex with GABA(C) receptors and PP1 in retinal bipolar cells; PNUTS and PP1 are detected in membrane fractions and co-precipitate with GABA(C) receptor antibodies; GABA(C) receptor co-expression causes PNUTS to shuttle from nucleus to membrane; simultaneous binding of PP1 and GABA(C) receptors to distinct domains of PNUTS was demonstrated.\",\n      \"method\": \"Co-immunoprecipitation, subcellular fractionation, immunofluorescence (localization shift), domain binding analysis\",\n      \"journal\": \"Molecular and cellular neurosciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP with domain mapping and localization shift; single lab\",\n      \"pmids\": [\"18325784\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PNUTS negatively regulates HIV-1 transcription by inhibiting assembly of the core P-TEFb components cyclin T1 and CDK9; overexpression of PNUTS potently and dose-dependently inhibits HIV-1 replication; miR-34a (upregulated by HIV-1) promotes replication by targeting PNUTS, creating a positive feedback loop.\",\n      \"method\": \"Overexpression/knockdown, luciferase reporter (HIV-1 LTR), co-immunoprecipitation (P-TEFb assembly), viral replication assay\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP of P-TEFb components with PNUTS overexpression/knockdown and viral replication readout; single lab\",\n      \"pmids\": [\"26188041\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"PNUTS is required for efficient termination of all major RNA Pol II transcript classes, including short ncRNAs and longer protein-coding transcripts; PNUTS is proximal to the Restrictor complex (ZC3H4-WDR82-ARS2) and enables Restrictor function; U1 snRNA shields coding transcripts from Restrictor and PNUTS at hundreds of genes.\",\n      \"method\": \"siRNA knockdown, ChIRP/ChIP, nascent RNA sequencing (TT-seq/GRO-seq), epistasis experiments\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genome-wide functional assay with epistasis across transcript classes; multiple orthogonal methods\",\n      \"pmids\": [\"37329883\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Efficient termination at Restrictor-controlled extragenic transcription units requires PNUTS (a negative regulator of SPT5 elongation factor) and Symplekin; PNUTS and Symplekin act synergistically with, but independently from, Restrictor to dampen processive extragenic transcription.\",\n      \"method\": \"siRNA knockdown, nascent RNA sequencing, epistasis experiments\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — nascent RNA-seq with genetic epistasis; single lab\",\n      \"pmids\": [\"38092518\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"The PNUTS-PP1 complex plays an essential role in transcription pause release in addition to termination; pause release by PNUTS-PP1 is required for almost all RNA Pol II-dependent gene transcription; this function depends on PP1 phosphatase activity and controls phosphorylation of factors required for pause release and elongation.\",\n      \"method\": \"CRISPR/genetic depletion, ChIP-seq, nascent RNA sequencing, PP1-binding mutant (W401A) analysis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genome-wide functional analysis with PP1-binding mutant and multiple readouts; defines a new essential function\",\n      \"pmids\": [\"39603239\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PP1/PNUTS co-purifies with the Restrictor complex (ZC3H4/WDR82); PNUTS binds directly to WDR82; AlphaFold predicts a quaternary PPWZ complex; a substrate-trap (inactive PP1H66K fused to PNUTS C-terminus) acts as dominant-negative inhibitor of antisense termination and CTD Ser5 dephosphorylation, demonstrating that phosphatase activity is required for restrictor-mediated termination; CTD Ser5 dephosphorylation by PPWZ promotes termination by increasing Pol II pausing.\",\n      \"method\": \"Co-immunoprecipitation, AlphaFold structural modeling, substrate-trap dominant-negative expression, NET-seq, ChIP-seq, CTD phospho-state analysis\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — substrate-trap mechanistic dissection combined with structural prediction and genome-wide transcriptomic readout; peer-reviewed\",\n      \"pmids\": [\"40244850\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PNUTS depletion causes CENP-A mislocalization to non-centromeric regions and chromosomal instability (CIN) in a PP1-dependent manner; CENP-C also mislocalizes; kinetochore integrity defects and micronuclei are observed; depletion of the H3.3 chaperone DAXX suppresses CENP-A mislocalization and micronuclei in PNUTS-depleted cells, defining a PNUTS→PP1→DAXX pathway controlling CENP-A deposition.\",\n      \"method\": \"Genome-wide siRNA screen, siRNA knockdown, immunofluorescence (CENP-A, CENP-C), micronuclei scoring, genetic epistasis (DAXX depletion)\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — genetic epistasis with DAXX plus multiple localization and CIN readouts; single lab\",\n      \"pmids\": [\"40270285\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In Drosophila, Tox4 requires zinc for binding the PNUTS TFIIS N-terminal domain (TND); Tox4 binds TND on a surface distinct from established TND-interacting transcriptional regulators; selective disruption of PNUTS-Tox4 or PNUTS-PP1 interactions impairs normal gene expression and chromosomal dispersal during oogenesis; tox4 is dispensable for viability but essential for fertility with PNUTS-dependent and -independent roles.\",\n      \"method\": \"Biochemical binding assays, structural analysis, in vivo Drosophila genetics (fertility/oogenesis), transcriptomics, site-directed mutagenesis\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — biochemical, structural, and in vivo genetic approaches in a single study; Drosophila ortholog\",\n      \"pmids\": [\"40347473\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In Drosophila germline, PNUTS and Senataxin associate with the SFiNX complex via Sov to initiate transposon silencing independent of H1 and HP1a heterochromatin; PNUTS mechanistically affects RNA Pol II elongation speed or stalling to induce transcriptional repression of transposable elements prior to heterochromatinization.\",\n      \"method\": \"Co-immunoprecipitation/mass spectrometry, genetic epistasis (H1, HP1a mutants), RNA Pol II ChIP/elongation assays in Drosophila\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP/MS and genetic epistasis in Drosophila; Drosophila ortholog, single study\",\n      \"pmids\": [\"41167190\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The N-terminal domain of PNUTS (PAD) adopts a compact globular fold rich in α-helical content, resembling an extended transcription factor TFIIS (S-II) leucine/tryptophan conserved-motif fold, with a melting temperature of ~49.5°C; this domain mediates interactions with Tox4 and PTEN.\",\n      \"method\": \"Circular dichroism, NMR spectroscopy, thermal denaturation, bioinformatics\",\n      \"journal\": \"The protein journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — NMR/CD structural characterization of isolated domain; single lab, no mutagenesis or full functional validation in this paper\",\n      \"pmids\": [\"27591855\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"PNUTS silencing in endothelial cells causes senescence, reduced angiogenesis, and loss of barrier function; PNUTS-PP1 axis regulates expression of semaphorin 3B (SEMA3B); silencing SEMA3B completely restores barrier function after PNUTS loss; endothelial-specific PNUTS knockout mice (Cdh5-CreERT2;PNUTSfl/fl) develop severe multiorgan failure and vascular leakage within two weeks.\",\n      \"method\": \"siRNA knockdown, conditional knockout mouse model (Cdh5-CreERT2;PNUTSfl/fl), transcriptomics, barrier function assays, senescence assays, epistasis (SEMA3B rescue)\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo conditional KO with defined downstream pathway (SEMA3B epistasis) and multiple orthogonal in vitro readouts\",\n      \"pmids\": [\"38714838\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PPP1R10/PNUTS is a nuclear PP1-targeting subunit that recruits PP1 to chromatin through direct interaction via an RVXF-related motif (requiring a critical Trp residue), where the PNUTS–PP1 holoenzyme dephosphorylates key substrates including the Rb protein, MYC, and the RNA Pol II CTD (Spt5, Ser5-P) to regulate transcription pause release, elongation speed, termination (including antisense and extragenic ncRNAs via association with the Restrictor/WDR82 complex), chromosome decondensation, DNA damage response/ATR signaling, CENP-A localization, and cell cycle progression; PKA phosphorylation of PNUTS's PP1-binding domain provides a regulatory switch that reduces PP1 association, and PNUTS also functions as a scaffold that sequesters PTEN in the nucleus and bridges PP1 to partners such as GABA(C) receptors, LCP1, and MYC at target gene promoters.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PPP1R10 (PNUTS/p99) is the principal nuclear targeting subunit of protein phosphatase 1 (PP1), forming a stable holoenzyme that directs and constrains PP1 catalytic activity on chromatin to control transcription, cell cycle progression, and genome stability [#0, #1]. PNUTS binds PP1 through a central ~50-residue domain in a highly extended, intrinsically disordered conformation, using an RVXF-like motif in which a critical tryptophan (W401) replaces the canonical phenylalanine; this contact blocks one of PP1's substrate-binding grooves to inhibit dephosphorylation of substrates such as Rb while leaving the active site available, and the W401A mutation abolishes both binding and the holoenzyme's activities [#1, #2, #3, #4]. PKA phosphorylation of the PP1-binding domain reduces PNUTS\\u2013PP1 association, providing a regulatory switch [#2]. The PNUTS\\u2013PP1 complex governs RNA Pol II dynamics genome-wide: it dephosphorylates the elongation factor Spt5 to decelerate Pol II and is required for transcription pause release as well as for termination, where Pol II deceleration downstream of poly(A) sites enables a 'sitting duck torpedo' mechanism [#10, #20]. Through direct binding to WDR82 and proximity to the Restrictor complex (ZC3H4/WDR82/ARS2) and Symplekin, PNUTS\\u2013PP1 dephosphorylates the Pol II CTD (Ser5) to enforce termination of protein-coding, antisense, and extragenic noncoding transcripts [#18, #19, #21]. Beyond transcription, PNUTS\\u2013PP1 dephosphorylates and stabilizes MYC at target-gene promoters via a direct MYC MB0\\u2013PNUTS PAD interaction, controlling MYC chromatin binding and SCF^FBXW7-mediated turnover [#9, #14]; promotes chromosome decondensation in telophase [#4]; restrains ATR signaling and replication stress in a manner dependent on the phospho-CTD reader CDC73 [#12, #13]; and controls CENP-A deposition through a PP1\\u2192DAXX pathway, maintaining kinetochore integrity and chromosomal stability [#22]. PNUTS additionally acts as a PP1-independent scaffold, sequestering PTEN in the nucleus via its C2 domain [#8] and bridging PP1 to partners including GABA(C) receptors and the transcriptional regulator LCP1 [#15, #16]. Endothelial PNUTS is required for vascular integrity in vivo, acting through the PNUTS\\u2013PP1 axis to repress SEMA3B [#26].\",\n  \"teleology\": [\n    {\n      \"year\": 1997,\n      \"claim\": \"Establishing that PPP1R10 is a bona fide PP1 regulatory subunit answered whether this nuclear protein controls phosphatase output, showing it potently inhibits PP1 catalytic activity.\",\n      \"evidence\": \"Biochemical purification of p99 from HeLa nuclei with in vitro phosphatase assays, identifying an atypical Trp in the PP1-binding motif\",\n      \"pmids\": [\"9450550\", \"9461602\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological substrates of the holoenzyme not yet defined\", \"Functional consequence of the atypical Trp motif unresolved\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Mapping the PP1-binding determinant defined how PNUTS docks and is regulated, identifying the essential W residue, PKA-dependent control, and a separable nucleic-acid-binding C-terminus.\",\n      \"evidence\": \"Truncation/mutagenesis with GST pulldown, in vitro phosphatase and PKA kinase assays, and RNA/ssDNA binding in 293T cells\",\n      \"pmids\": [\"12574161\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo relevance of RNA binding not established\", \"Which substrates are gated by PKA phosphorylation unknown\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Atomic-resolution structure explained the inhibitory mechanism, showing PNUTS binds PP1 in an extended manner and occludes the arginine substrate groove rather than the active site.\",\n      \"evidence\": \"NMR and X-ray crystallography of the PNUTS\\u2013PP1 complex with biochemical and mutagenesis validation against Rb dephosphorylation\",\n      \"pmids\": [\"24591642\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure of full-length, intrinsically disordered PNUTS not determined\", \"How substrate selectivity is achieved in cells not resolved\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Linking PNUTS to Rb dephosphorylation answered which cell-cycle substrate the holoenzyme gates, showing PNUTS inhibits PP1 toward pRb and dissociates under hypoxia.\",\n      \"evidence\": \"In vitro pRb-directed phosphatase assay with GST-PNUTS and hypoxia treatment of cells\",\n      \"pmids\": [\"12270115\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism coupling hypoxia to PNUTS\\u2013PP1 dissociation unknown\", \"Cellular hypoxia correlate not mechanistically tied to phosphatase change\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Connecting PNUTS to mitotic exit showed the holoenzyme drives chromatin decondensation, establishing a structural role for PP1 targeting at telophase.\",\n      \"evidence\": \"Subcellular fractionation, in vitro chromosome decondensation assays in defined buffer, and W401A mutagenesis\",\n      \"pmids\": [\"15907195\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct chromatin substrate dephosphorylated during decondensation not identified\", \"Recruitment mechanism to reforming nuclei unclear\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Genetic epistasis defined the consequence of losing PNUTS in cancer cells, showing PNUTS loss unleashes PP1 on Rb to trigger E2F1 release and caspase-8 apoptosis selectively in Rb-expressing cells.\",\n      \"evidence\": \"siRNA knockdown with Rb-null vs Rb-expressing cell panel, Rb-phosphatase and apoptosis assays\",\n      \"pmids\": [\"18360108\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Why normal cells are spared not mechanistically resolved\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Discovery of a PNUTS\\u2013PP1\\u2013GABA(C) receptor complex showed PNUTS can act as a membrane-targeting scaffold outside the nucleus.\",\n      \"evidence\": \"Co-IP, subcellular fractionation, and localization shift upon receptor co-expression in retinal bipolar cells\",\n      \"pmids\": [\"18325784\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional output of receptor-associated PP1 not defined\", \"Single lab; physiological context limited\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Identifying the PNUTS\\u2013LCP1 interaction showed PNUTS has a PP1-independent transcriptional-repression function distinct from its phosphatase-targeting role.\",\n      \"evidence\": \"Yeast two-hybrid, Co-IP domain mapping, nuclear speckle co-localization, and GAL4 reporter assays\",\n      \"pmids\": [\"19293638\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Endogenous target genes of LCP1 repression unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Implicating PNUTS in the DNA damage response showed it restrains G2 checkpoint activation and supports repair, recruiting transiently to damage sites.\",\n      \"evidence\": \"siRNA knockdown, live-cell imaging of PNUTS-EGFP recruitment, cell-cycle flow cytometry, repair foci, and clonogenic survival after IR\",\n      \"pmids\": [\"20890310\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Substrate dephosphorylated at damage sites not identified\", \"Whether checkpoint role is PP1-dependent not directly tested here\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identifying PTEN sequestration showed PNUTS scaffolds a tumor suppressor in the nucleus, defining a PP1-independent function via the PTEN C2 domain.\",\n      \"evidence\": \"Co-IP, GST pulldown domain mapping, siRNA knockdown with PTEN-dependent viability/apoptosis readouts\",\n      \"pmids\": [\"23117887\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Regulation of PTEN nuclear/cytoplasmic shuttling by PNUTS unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Linking PNUTS to HIV-1 transcription showed it negatively regulates P-TEFb assembly, embedding it in a viral miR-34a feedback loop.\",\n      \"evidence\": \"Overexpression/knockdown, HIV-1 LTR luciferase reporter, Co-IP of cyclin T1/CDK9, and replication assays\",\n      \"pmids\": [\"26188041\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether PP1 activity is required for P-TEFb inhibition not resolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defining the MYC connection showed PNUTS\\u2013PP1 dephosphorylates and stabilizes MYC at promoters, controlling MYC chromatin binding and FBXW7-mediated turnover.\",\n      \"evidence\": \"BioID-MS, Co-IP, ChIP, RNAi, pharmacological PP1 inhibition, and phospho-site mass spectrometry across multiple cell types\",\n      \"pmids\": [\"30158517\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct PNUTS-PP1 MYC phospho-sites not all mapped to function in this study\", \"Interface of MYC contact not yet structurally defined here\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Linking PNUTS to mitotic fidelity showed it associates with Aurora kinases/kinetochore components and is required for CPC regulation and spindle checkpoint signaling.\",\n      \"evidence\": \"siRNA knockdown, Co-IP/MS, kinetochore immunofluorescence, kinase assays, and live-cell imaging\",\n      \"pmids\": [\"30190438\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether PNUTS-PP1 phosphatase activity drives Aurora regulation not separated\", \"Single lab\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Genome-wide elongation profiling established that PNUTS-PP1 decelerates Pol II via Spt5 dephosphorylation, defining a 'sitting duck torpedo' termination model dependent on poly(A) recognition.\",\n      \"evidence\": \"TT-seq, ChIP-seq, W401A mutagenesis, and phospho-Spt5 analysis with in vivo elongation rate measurement\",\n      \"pmids\": [\"31677974\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How poly(A) site recognition is coupled to PP1 recruitment unresolved\", \"Full set of CTD/elongation substrates not enumerated\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Connecting PNUTS-PP1 to replication stress showed that loss elevates ATR signaling via R-loops in a CDC73-dependent manner, independent of canonical damage markers.\",\n      \"evidence\": \"siRNA knockdown, pATR/\\u03b3H2AX immunofluorescence, R-loop detection, Co-IP of ATR/RNAPII/CDC73, and cell-cycle analysis\",\n      \"pmids\": [\"30541148\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which CDC73 promotes R-loops not defined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Showing PNUTS-PP1 suppresses replication stress via CTD dephosphorylation established that it limits RNAPII chromatin residence and promotes proteasomal RNAPII turnover with WDR82.\",\n      \"evidence\": \"siRNA knockdown, EdU incorporation, FRAP of RNAPII, DNA fiber assays, proteasome inhibition, and CDC73 epistasis\",\n      \"pmids\": [\"33264625\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct trigger for proteasomal RNAPII degradation unclear\", \"How transcription-replication conflicts are resolved mechanistically open\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Structural definition of the MYC\\u2013PNUTS interface answered how PNUTS engages MYC, showing MYC MB0 binds the PNUTS PAD and that interface mutations elevate MYC phosphorylation.\",\n      \"evidence\": \"NMR solution structure of PAD, in vitro binding, mutagenesis, and cellular Co-IP\",\n      \"pmids\": [\"35244724\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How PP1 catalysis is positioned on MYC by this interface not shown\", \"In vivo tumor relevance of interface mutations untested here\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Connecting PNUTS to the Restrictor pathway showed it enables termination of all major Pol II transcript classes, with U1 snRNA shielding coding transcripts.\",\n      \"evidence\": \"siRNA knockdown, ChIRP/ChIP, and nascent RNA sequencing with epistasis\",\n      \"pmids\": [\"37329883\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of PNUTS\\u2013Restrictor proximity not structurally defined here\", \"How U1 antagonizes PNUTS function unresolved\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defining PNUTS\\u2013Symplekin cooperation showed PNUTS dampens processive extragenic transcription synergistically with, but independently from, Restrictor.\",\n      \"evidence\": \"siRNA knockdown and nascent RNA sequencing with genetic epistasis\",\n      \"pmids\": [\"38092518\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic basis of Symplekin synergy unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Establishing PNUTS-PP1 in pause release showed it is required for nearly all Pol II-dependent transcription, dependent on PP1 catalytic activity.\",\n      \"evidence\": \"CRISPR/genetic depletion, ChIP-seq, nascent RNA sequencing, and W401A mutant analysis\",\n      \"pmids\": [\"39603239\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific pause-release substrate phospho-sites not fully mapped\", \"How pause-release and termination roles are temporally coordinated open\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"An endothelial conditional knockout established an in vivo physiological role, showing PNUTS-PP1 maintains vascular barrier function by repressing SEMA3B.\",\n      \"evidence\": \"Cdh5-CreERT2;PNUTSfl/fl mice, siRNA knockdown, transcriptomics, barrier/senescence assays, and SEMA3B rescue\",\n      \"pmids\": [\"38714838\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How PNUTS-PP1 controls SEMA3B transcription mechanistically unclear\", \"Tissue specificity of the phenotype not fully explained\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Substrate-trap dissection of the PPWZ complex showed PNUTS binds WDR82 directly and that PP1 catalytic activity dephosphorylating CTD Ser5 is required for Restrictor-mediated termination.\",\n      \"evidence\": \"Co-IP, AlphaFold modeling, dominant-negative PP1H66K substrate trap, NET-seq, ChIP-seq, and CTD phospho-state analysis\",\n      \"pmids\": [\"40244850\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Experimental structure of the PPWZ quaternary complex lacking\", \"How CTD Ser5 dephosphorylation increases pausing mechanistically open\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defining a PNUTS\\u2192PP1\\u2192DAXX axis showed PNUTS controls CENP-A deposition and chromosomal stability, with DAXX loss suppressing CENP-A mislocalization.\",\n      \"evidence\": \"Genome-wide siRNA screen, knockdown, CENP-A/CENP-C immunofluorescence, micronuclei scoring, and DAXX epistasis\",\n      \"pmids\": [\"40270285\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct PP1 substrate in the DAXX pathway not identified\", \"Single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Drosophila studies extended PNUTS function to germline biology, showing zinc-dependent Tox4 binding to the PNUTS TND and roles in transposon silencing via SFiNX/Senataxin.\",\n      \"evidence\": \"Biochemical/structural binding assays and in vivo Drosophila genetics, transcriptomics, and Pol II ChIP\",\n      \"pmids\": [\"40347473\", \"41167190\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Conservation of these roles in mammals untested\", \"Drosophila ortholog; direct PP1 substrates in transposon silencing unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the multiple PNUTS-PP1 chromatin functions (pause release, termination, CTD/Spt5 dephosphorylation, CENP-A deposition, MYC stabilization, DNA damage response) are spatially and temporally coordinated by a single targeting subunit remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying model for substrate selection in vivo\", \"Structure of full-length PNUTS holoenzyme on chromatin lacking\", \"Direct dephosphorylation substrate maps incomplete for most pathways\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 2, 3]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [3, 9, 10, 20, 21]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [8, 15, 16, 21]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [2]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [2]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [15]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [1, 15]},\n      {\"term_id\": \"GO:0005730\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [0, 4]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [16]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [10, 18, 20, 21]},\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [18, 19, 21]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [4, 6, 7, 11]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [7, 12, 13]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [8, 9]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [6, 8]}\n    ],\n    \"complexes\": [\n      \"PNUTS-PP1 holoenzyme\",\n      \"Restrictor complex (ZC3H4/WDR82/ARS2)\",\n      \"PPWZ complex (PP1-PNUTS-WDR82-ZC3H4)\"\n    ],\n    \"partners\": [\n      \"PPP1CA\",\n      \"WDR82\",\n      \"MYC\",\n      \"PTEN\",\n      \"LCP1\",\n      \"CDC73\",\n      \"TOX4\",\n      \"ZC3H4\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}