{"gene":"PATL1","run_date":"2026-06-10T05:19:53","timeline":{"discoveries":[{"year":2007,"finding":"PATL1 (PatL1) protein localizes to cytoplasmic processing bodies (P bodies), co-localizing with P body components Lsm1, Rck/p54, and the decapping enzyme Dcp1. PatL1 expression is required for P body formation.","method":"Fluorescence microscopy with tagged PatL1, co-localization with P body markers, RNAi knockdown with P body formation as readout","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiment with functional consequence (P body formation), single lab but two orthogonal methods (co-localization + loss-of-function)","pmids":["17936923"],"is_preprint":false},{"year":2010,"finding":"Human Pat1b physically associates with the Ccr4-Caf1-Not deadenylation complex, the Dcp1-Dcp2 decapping complex, the RNA helicase Rck, and Lsm1 proteins via at least three independent domains, functioning as a scaffold that connects deadenylation with decapping. Tethering Pat1b to a reporter mRNA promotes both deadenylation and decapping.","method":"Co-immunoprecipitation, tethering assay with reporter mRNA, domain deletion analysis","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal co-IP identifying multiple complexes, functional tethering assay, domain mapping; replicated across multiple orthogonal methods in one rigorous study","pmids":["20584987"],"is_preprint":false},{"year":2010,"finding":"Pat1b contains an amino-terminal aggregation-prone domain that nucleates P body formation, and an acidic domain that controls P body size.","method":"Domain deletion/mutation analysis with P body formation as readout in human cells","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct loss-of-function domain mapping with defined cellular phenotype, single lab","pmids":["20584987"],"is_preprint":false},{"year":2010,"finding":"Pat1b acts as an mRNA deadenylation factor: when tethered to a reporter mRNA in HeLa cells, it represses gene expression by inducing deadenylation, and was identified as the human LSm1-interacting Pat1p homolog by immunoprecipitation and mass spectrometry.","method":"Novel immunoprecipitation followed by mass spectrometry to identify Pat1b; tethering assay with deadenylation readout","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — MS identification plus functional tethering assay, single lab, two orthogonal methods","pmids":["20852261"],"is_preprint":false},{"year":2011,"finding":"Pat1b is a nucleocytoplasmic shuttling protein; its nuclear export is mediated by a consensus NES sequence via the Crm1 export pathway (blocked by leptomycin B). Nuclear Pat1b localizes to PML-associated foci, SC35-containing splicing speckles (in a transcription-dependent manner), and nucleolar caps (when transcription is inhibited), with distinct regions of Pat1b mediating retention in each compartment.","method":"Leptomycin B treatment, immunofluorescence microscopy, domain mapping of nuclear retention, spliceostatin A treatment","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization with pharmacological perturbation and domain mapping, single lab, multiple orthogonal approaches","pmids":["22090346"],"is_preprint":false},{"year":2012,"finding":"PATL1 interacts with ALG-2 (PDCD6), a Ca2+-binding penta-EF-hand protein, via an ALG-2-binding motif in PATL1's proline-rich region. Endogenous PATL1 and ALG-2 co-immunoprecipitate, and a subset of ALG-2 co-localizes with PATL1 and DCP1A at P bodies.","method":"In silico screening, Far-Western blotting with biotinylated ALG-2, co-immunoprecipitation of endogenous proteins, immunofluorescence co-localization","journal":"Journal of biochemistry","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP of endogenous proteins plus Far-Western and co-localization, single lab, multiple methods but no functional consequence established","pmids":["22437941"],"is_preprint":false},{"year":2013,"finding":"The C-terminal RecA-like domain of Rck interacts with the N-terminal acidic domain of Pat1b. Point mutations disrupting this interaction show that Pat1b can assemble P bodies and suppress expression of tethered mRNAs independently of Rck binding, whereas Rck requires the Pat1b-binding site to promote P body assembly and to associate with the decapping enzyme Dcp2, Ago2, and TNRC6A. This defines a stepwise P body assembly where Rck suppresses mRNA translation first, and Pat1b subsequently triggers P body assembly and promotes mRNA decapping.","method":"Interaction-deficient point mutations, co-immunoprecipitation, RNAi knockdown with rescue, tethering assay, immunofluorescence","journal":"RNA biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — point mutagenesis abolishing specific interaction, combined with epistasis via knockdown/rescue and multiple functional readouts (P body formation, mRNA repression, protein interactions) in a single rigorous study","pmids":["23535175"],"is_preprint":false},{"year":2017,"finding":"Pat1b forms a nuclear complex with the Lsm2-8 heptamer (distinct from the cytoplasmic Lsm1-7 complex) that binds U6 snRNA. This nuclear Pat1b/Lsm2-8/U6 snRNA complex also connects with SART3 and additional U4/U6.U5 tri-snRNP components in Cajal bodies. Pat1b depletion preferentially upregulates mRNAs enriched in 3' UTR AU-rich elements normally found in P bodies, and causes >180 alternative splicing changes characterized by skipping of regulated exons with weak donor sites.","method":"Co-immunoprecipitation, immunofluorescence, RNAi depletion, RNA sequencing for mRNA level and splicing changes","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal co-IP identifying nuclear complex, RNA-seq providing genome-wide functional readout, immunofluorescence for localization, multiple orthogonal methods in one study","pmids":["28768202"],"is_preprint":false},{"year":2023,"finding":"PATL1 (and PATL2) interact with TFIIE, a general transcription factor required for forming the RNA polymerase II preinitiation complex, and facilitate transcription of hERG mRNA as shown by dual-luciferase reporter assays. Knockdown of PATL1/PATL2 decreases hERG protein levels and current density in human cells and hiPSC-derived cardiomyocytes, and elongates action potential duration.","method":"Forward genetic screen in C. elegans, RNAi knockdown in SH-SY5Y cells and hiPSC-CMs, co-immunoprecipitation with TFIIE, dual-luciferase reporter assay, electrophysiology","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP with TFIIE plus functional reporter assay and electrophysiological readout, single lab, multiple orthogonal methods but PATL1 and PATL2 not always distinguished","pmids":["36608291"],"is_preprint":false}],"current_model":"PATL1 (Pat1b) is a multi-domain scaffold protein central to cytoplasmic mRNA decay, physically bridging the Ccr4-Caf1-Not deadenylation complex with the Dcp1-Dcp2 decapping machinery and the Lsm1-7/Rck complex via distinct protein domains; it promotes deadenylation and decapping of target mRNAs (enriched in AU-rich elements), nucleates P body formation through an aggregation-prone N-terminal domain, and also shuttles to the nucleus via a CRM1-dependent NES where it forms a distinct complex with Lsm2-8/U6 snRNA/SART3 in Cajal bodies to regulate alternative splicing, while additionally interacting with TFIIE to facilitate transcription of specific genes such as hERG."},"narrative":{"mechanistic_narrative":"PATL1 (Pat1b) is a multi-domain scaffold protein that orchestrates cytoplasmic mRNA turnover by physically coupling deadenylation to decapping [PMID:20584987]. Through at least three independent domains it bridges the Ccr4-Caf1-Not deadenylation complex, the Dcp1-Dcp2 decapping enzymes, the RNA helicase Rck, and Lsm1; tethering Pat1b to a reporter mRNA promotes both deadenylation and decapping, repressing expression [PMID:20584987, PMID:20852261]. It nucleates processing body (P body) assembly via an aggregation-prone N-terminal domain, with an acidic domain setting P body size, and is required for P body formation [PMID:17936923, PMID:20584987]. Within this process PATL1 acts downstream of Rck in a stepwise order: Rck first suppresses translation, then Pat1b triggers P body assembly and decapping, with the Rck RecA-like domain engaging the Pat1b N-terminal acidic domain [PMID:23535175]. PATL1 is also a nucleocytoplasmic shuttling protein exported through a CRM1-dependent NES, where nuclear PATL1 forms a distinct complex with the Lsm2-8 heptamer and U6 snRNA, connects to SART3 and U4/U6.U5 tri-snRNP components in Cajal bodies, and regulates alternative splicing; its depletion upregulates AU-rich-element-enriched mRNAs and skews regulated exon skipping [PMID:22090346, PMID:28768202]. Beyond RNA metabolism, PATL1 interacts with the general transcription factor TFIIE to facilitate transcription of hERG, influencing cardiomyocyte action potential duration [PMID:36608291].","teleology":[{"year":2007,"claim":"Established that PATL1 is a bona fide P body component whose presence is required for P body formation, placing it at the heart of cytoplasmic mRNA storage/decay foci.","evidence":"Tagged PatL1 co-localization with Lsm1, Rck/p54 and Dcp1 plus RNAi knockdown scored for P body formation","pmids":["17936923"],"confidence":"Medium","gaps":["Did not define which domains drive P body nucleation","No biochemical demonstration of direct partner binding"]},{"year":2010,"claim":"Resolved how PATL1 acts molecularly by showing it is a scaffold connecting deadenylation and decapping machineries, answering whether it merely resides in P bodies or actively drives decay.","evidence":"Reciprocal co-IP of Ccr4-Caf1-Not, Dcp1-Dcp2, Rck and Lsm1, domain deletion mapping, and tethering assays measuring deadenylation/decapping in HeLa cells","pmids":["20584987","20852261"],"confidence":"High","gaps":["Did not establish target mRNA selectivity genome-wide","Stepwise order of recruitment relative to Rck not yet defined"]},{"year":2010,"claim":"Mapped the structural determinants of P body biogenesis to an N-terminal aggregation-prone domain that nucleates assembly and an acidic domain that controls foci size.","evidence":"Domain deletion/mutation analysis with P body formation readout in human cells","pmids":["20584987"],"confidence":"Medium","gaps":["Molecular basis of the aggregation propensity not determined","No in vitro reconstitution of nucleation"]},{"year":2011,"claim":"Revealed an unanticipated nuclear life for PATL1, showing it shuttles via a CRM1-dependent NES and occupies distinct nuclear compartments, expanding its role beyond cytoplasmic decay.","evidence":"Leptomycin B and spliceostatin A treatment, immunofluorescence, and domain mapping of nuclear retention","pmids":["22090346"],"confidence":"Medium","gaps":["Functional consequence of nuclear localization not yet established","Identity of nuclear binding partners undefined"]},{"year":2012,"claim":"Identified ALG-2 (PDCD6) as a Ca2+-dependent partner of PATL1, suggesting a link between calcium signaling and P body composition.","evidence":"In silico motif screening, Far-Western blotting, endogenous co-immunoprecipitation, and co-localization with DCP1A at P bodies","pmids":["22437941"],"confidence":"Medium","gaps":["No functional consequence of the PATL1-ALG-2 interaction established","Calcium dependence of the interaction in cells not demonstrated"]},{"year":2013,"claim":"Defined a stepwise P body assembly pathway, distinguishing Rck's translational suppression from PATL1's downstream role in triggering foci assembly and decapping.","evidence":"Interaction-deficient point mutations, co-IP, RNAi knockdown with rescue, tethering assays, and immunofluorescence","pmids":["23535175"],"confidence":"High","gaps":["Kinetics of the ordered assembly not directly measured","Whether the order generalizes to all target mRNAs unknown"]},{"year":2017,"claim":"Demonstrated that nuclear PATL1 forms a distinct Lsm2-8/U6 snRNA/SART3 complex in Cajal bodies and regulates alternative splicing, giving the nuclear pool a concrete mechanistic function.","evidence":"Reciprocal co-IP, immunofluorescence, RNAi depletion, and RNA sequencing for mRNA levels and splicing changes","pmids":["28768202"],"confidence":"High","gaps":["Mechanism by which PATL1 selects exons with weak donor sites unresolved","Direct contact with splicing machinery vs. indirect effect not separated"]},{"year":2023,"claim":"Connected PATL1 to transcriptional control by showing it binds TFIIE and promotes hERG expression, linking the protein to cardiomyocyte electrophysiology.","evidence":"C. elegans forward genetic screen, RNAi in SH-SY5Y and hiPSC-CMs, co-IP with TFIIE, dual-luciferase reporter, and electrophysiology","pmids":["36608291"],"confidence":"Medium","gaps":["PATL1 and PATL2 contributions not always separated","Whether TFIIE binding is direct and gene-selective mechanism unresolved"]},{"year":null,"claim":"How PATL1 partitions and is regulated between its cytoplasmic decay, nuclear splicing, and transcriptional roles, and what determines target selectivity in each, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No integrated regulatory model linking the three compartmental functions","Signals controlling nucleocytoplasmic shuttling in vivo unknown","Target specificity determinants for decay vs. splicing vs. transcription undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,6]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[7]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,3]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0,1,2]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[4,7]},{"term_id":"GO:0005730","term_label":"nucleolus","supporting_discovery_ids":[4]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[1,7]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[8]}],"complexes":["Lsm2-8/U6 snRNA/SART3 nuclear complex","P body"],"partners":["DDX6","LSM1","DCP1A","DCP2","PDCD6","SART3","TFIIE"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q86TB9","full_name":"Protein PAT1 homolog 1","aliases":["PAT1-like protein 1","Protein PAT1 homolog b","Pat1b","hPat1b"],"length_aa":770,"mass_kda":86.8,"function":"RNA-binding protein involved in deadenylation-dependent decapping of mRNAs, leading to the degradation of mRNAs (PubMed:17936923, PubMed:20543818, PubMed:20584987, PubMed:20852261). Acts as a scaffold protein that connects deadenylation and decapping machinery (PubMed:17936923, PubMed:20543818, PubMed:20584987, PubMed:20852261). Required for cytoplasmic mRNA processing body (P-body) assembly (PubMed:17936923, PubMed:20543818, PubMed:20584987, PubMed:20852261) (Microbial infection) In case of infection, required for translation and replication of hepatitis C virus (HCV)","subcellular_location":"Cytoplasm, P-body; Nucleus; Nucleus, PML body; Nucleus speckle","url":"https://www.uniprot.org/uniprotkb/Q86TB9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PATL1","classification":"Not Classified","n_dependent_lines":5,"n_total_lines":1208,"dependency_fraction":0.0041390728476821195},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CLTA","stoichiometry":0.2},{"gene":"DDX6","stoichiometry":0.2},{"gene":"ITSN1","stoichiometry":0.2},{"gene":"PACSIN3","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/PATL1","total_profiled":1310},"omim":[{"mim_id":"614661","title":"PAT1 HOMOLOG 2; PATL2","url":"https://www.omim.org/entry/614661"},{"mim_id":"614660","title":"PAT1 HOMOLOG 1, PROCESSING BODY mRNA DECAY FACTOR; PATL1","url":"https://www.omim.org/entry/614660"},{"mim_id":"607281","title":"LSM1 HOMOLOG, mRNA DEGRADATION-ASSOCIATED; LSM1","url":"https://www.omim.org/entry/607281"},{"mim_id":"600326","title":"DEAD-BOX HELICASE 6; DDX6","url":"https://www.omim.org/entry/600326"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytoplasmic bodies","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PATL1"},"hgnc":{"alias_symbol":["FLJ36874","Pat1b"],"prev_symbol":[]},"alphafold":{"accession":"Q86TB9","domains":[{"cath_id":"1.20.870","chopping":"651-770","consensus_level":"medium","plddt":86.5639,"start":651,"end":770}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q86TB9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q86TB9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q86TB9-F1-predicted_aligned_error_v6.png","plddt_mean":61.03},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PATL1","jax_strain_url":"https://www.jax.org/strain/search?query=PATL1"},"sequence":{"accession":"Q86TB9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q86TB9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q86TB9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q86TB9"}},"corpus_meta":[{"pmid":"20584987","id":"PMC_20584987","title":"Human Pat1b connects deadenylation with mRNA decapping and controls the assembly of processing bodies.","date":"2010","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/20584987","citation_count":113,"is_preprint":false},{"pmid":"17936923","id":"PMC_17936923","title":"Identification of PatL1, a human homolog to yeast P body component Pat1.","date":"2007","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/17936923","citation_count":50,"is_preprint":false},{"pmid":"22090346","id":"PMC_22090346","title":"RNA-related nuclear functions of human Pat1b, the P-body mRNA decay factor.","date":"2011","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/22090346","citation_count":35,"is_preprint":false},{"pmid":"28768202","id":"PMC_28768202","title":"Dual RNA Processing Roles of Pat1b via Cytoplasmic Lsm1-7 and Nuclear Lsm2-8 Complexes.","date":"2017","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/28768202","citation_count":29,"is_preprint":false},{"pmid":"20852261","id":"PMC_20852261","title":"The human Pat1b protein: a novel mRNA deadenylation factor identified by a new immunoprecipitation technique.","date":"2010","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/20852261","citation_count":27,"is_preprint":false},{"pmid":"23535175","id":"PMC_23535175","title":"Role of Rck-Pat1b binding in assembly of processing-bodies.","date":"2013","source":"RNA biology","url":"https://pubmed.ncbi.nlm.nih.gov/23535175","citation_count":16,"is_preprint":false},{"pmid":"22437941","id":"PMC_22437941","title":"Identification of the P-body component PATL1 as a novel ALG-2-interacting protein by in silico and far-Western screening of proline-rich proteins.","date":"2012","source":"Journal of biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22437941","citation_count":16,"is_preprint":false},{"pmid":"36608291","id":"PMC_36608291","title":"DNA topoisomerase 2-associated proteins PATL1 and PATL2 regulate the biogenesis of hERG K+ channels.","date":"2023","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/36608291","citation_count":5,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":5798,"output_tokens":2469,"usd":0.027214,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9593,"output_tokens":3043,"usd":0.06202,"stage2_stop_reason":"end_turn"},"total_usd":0.089234,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2007,\n      \"finding\": \"PATL1 (PatL1) protein localizes to cytoplasmic processing bodies (P bodies), co-localizing with P body components Lsm1, Rck/p54, and the decapping enzyme Dcp1. PatL1 expression is required for P body formation.\",\n      \"method\": \"Fluorescence microscopy with tagged PatL1, co-localization with P body markers, RNAi knockdown with P body formation as readout\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiment with functional consequence (P body formation), single lab but two orthogonal methods (co-localization + loss-of-function)\",\n      \"pmids\": [\"17936923\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Human Pat1b physically associates with the Ccr4-Caf1-Not deadenylation complex, the Dcp1-Dcp2 decapping complex, the RNA helicase Rck, and Lsm1 proteins via at least three independent domains, functioning as a scaffold that connects deadenylation with decapping. Tethering Pat1b to a reporter mRNA promotes both deadenylation and decapping.\",\n      \"method\": \"Co-immunoprecipitation, tethering assay with reporter mRNA, domain deletion analysis\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal co-IP identifying multiple complexes, functional tethering assay, domain mapping; replicated across multiple orthogonal methods in one rigorous study\",\n      \"pmids\": [\"20584987\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Pat1b contains an amino-terminal aggregation-prone domain that nucleates P body formation, and an acidic domain that controls P body size.\",\n      \"method\": \"Domain deletion/mutation analysis with P body formation as readout in human cells\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct loss-of-function domain mapping with defined cellular phenotype, single lab\",\n      \"pmids\": [\"20584987\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Pat1b acts as an mRNA deadenylation factor: when tethered to a reporter mRNA in HeLa cells, it represses gene expression by inducing deadenylation, and was identified as the human LSm1-interacting Pat1p homolog by immunoprecipitation and mass spectrometry.\",\n      \"method\": \"Novel immunoprecipitation followed by mass spectrometry to identify Pat1b; tethering assay with deadenylation readout\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — MS identification plus functional tethering assay, single lab, two orthogonal methods\",\n      \"pmids\": [\"20852261\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Pat1b is a nucleocytoplasmic shuttling protein; its nuclear export is mediated by a consensus NES sequence via the Crm1 export pathway (blocked by leptomycin B). Nuclear Pat1b localizes to PML-associated foci, SC35-containing splicing speckles (in a transcription-dependent manner), and nucleolar caps (when transcription is inhibited), with distinct regions of Pat1b mediating retention in each compartment.\",\n      \"method\": \"Leptomycin B treatment, immunofluorescence microscopy, domain mapping of nuclear retention, spliceostatin A treatment\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization with pharmacological perturbation and domain mapping, single lab, multiple orthogonal approaches\",\n      \"pmids\": [\"22090346\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PATL1 interacts with ALG-2 (PDCD6), a Ca2+-binding penta-EF-hand protein, via an ALG-2-binding motif in PATL1's proline-rich region. Endogenous PATL1 and ALG-2 co-immunoprecipitate, and a subset of ALG-2 co-localizes with PATL1 and DCP1A at P bodies.\",\n      \"method\": \"In silico screening, Far-Western blotting with biotinylated ALG-2, co-immunoprecipitation of endogenous proteins, immunofluorescence co-localization\",\n      \"journal\": \"Journal of biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP of endogenous proteins plus Far-Western and co-localization, single lab, multiple methods but no functional consequence established\",\n      \"pmids\": [\"22437941\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"The C-terminal RecA-like domain of Rck interacts with the N-terminal acidic domain of Pat1b. Point mutations disrupting this interaction show that Pat1b can assemble P bodies and suppress expression of tethered mRNAs independently of Rck binding, whereas Rck requires the Pat1b-binding site to promote P body assembly and to associate with the decapping enzyme Dcp2, Ago2, and TNRC6A. This defines a stepwise P body assembly where Rck suppresses mRNA translation first, and Pat1b subsequently triggers P body assembly and promotes mRNA decapping.\",\n      \"method\": \"Interaction-deficient point mutations, co-immunoprecipitation, RNAi knockdown with rescue, tethering assay, immunofluorescence\",\n      \"journal\": \"RNA biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — point mutagenesis abolishing specific interaction, combined with epistasis via knockdown/rescue and multiple functional readouts (P body formation, mRNA repression, protein interactions) in a single rigorous study\",\n      \"pmids\": [\"23535175\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Pat1b forms a nuclear complex with the Lsm2-8 heptamer (distinct from the cytoplasmic Lsm1-7 complex) that binds U6 snRNA. This nuclear Pat1b/Lsm2-8/U6 snRNA complex also connects with SART3 and additional U4/U6.U5 tri-snRNP components in Cajal bodies. Pat1b depletion preferentially upregulates mRNAs enriched in 3' UTR AU-rich elements normally found in P bodies, and causes >180 alternative splicing changes characterized by skipping of regulated exons with weak donor sites.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence, RNAi depletion, RNA sequencing for mRNA level and splicing changes\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal co-IP identifying nuclear complex, RNA-seq providing genome-wide functional readout, immunofluorescence for localization, multiple orthogonal methods in one study\",\n      \"pmids\": [\"28768202\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"PATL1 (and PATL2) interact with TFIIE, a general transcription factor required for forming the RNA polymerase II preinitiation complex, and facilitate transcription of hERG mRNA as shown by dual-luciferase reporter assays. Knockdown of PATL1/PATL2 decreases hERG protein levels and current density in human cells and hiPSC-derived cardiomyocytes, and elongates action potential duration.\",\n      \"method\": \"Forward genetic screen in C. elegans, RNAi knockdown in SH-SY5Y cells and hiPSC-CMs, co-immunoprecipitation with TFIIE, dual-luciferase reporter assay, electrophysiology\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP with TFIIE plus functional reporter assay and electrophysiological readout, single lab, multiple orthogonal methods but PATL1 and PATL2 not always distinguished\",\n      \"pmids\": [\"36608291\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PATL1 (Pat1b) is a multi-domain scaffold protein central to cytoplasmic mRNA decay, physically bridging the Ccr4-Caf1-Not deadenylation complex with the Dcp1-Dcp2 decapping machinery and the Lsm1-7/Rck complex via distinct protein domains; it promotes deadenylation and decapping of target mRNAs (enriched in AU-rich elements), nucleates P body formation through an aggregation-prone N-terminal domain, and also shuttles to the nucleus via a CRM1-dependent NES where it forms a distinct complex with Lsm2-8/U6 snRNA/SART3 in Cajal bodies to regulate alternative splicing, while additionally interacting with TFIIE to facilitate transcription of specific genes such as hERG.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PATL1 (Pat1b) is a multi-domain scaffold protein that orchestrates cytoplasmic mRNA turnover by physically coupling deadenylation to decapping [#1]. Through at least three independent domains it bridges the Ccr4-Caf1-Not deadenylation complex, the Dcp1-Dcp2 decapping enzymes, the RNA helicase Rck, and Lsm1; tethering Pat1b to a reporter mRNA promotes both deadenylation and decapping, repressing expression [#1, #3]. It nucleates processing body (P body) assembly via an aggregation-prone N-terminal domain, with an acidic domain setting P body size, and is required for P body formation [#0, #2]. Within this process PATL1 acts downstream of Rck in a stepwise order: Rck first suppresses translation, then Pat1b triggers P body assembly and decapping, with the Rck RecA-like domain engaging the Pat1b N-terminal acidic domain [#6]. PATL1 is also a nucleocytoplasmic shuttling protein exported through a CRM1-dependent NES, where nuclear PATL1 forms a distinct complex with the Lsm2-8 heptamer and U6 snRNA, connects to SART3 and U4/U6.U5 tri-snRNP components in Cajal bodies, and regulates alternative splicing; its depletion upregulates AU-rich-element-enriched mRNAs and skews regulated exon skipping [#4, #7]. Beyond RNA metabolism, PATL1 interacts with the general transcription factor TFIIE to facilitate transcription of hERG, influencing cardiomyocyte action potential duration [#8].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Established that PATL1 is a bona fide P body component whose presence is required for P body formation, placing it at the heart of cytoplasmic mRNA storage/decay foci.\",\n      \"evidence\": \"Tagged PatL1 co-localization with Lsm1, Rck/p54 and Dcp1 plus RNAi knockdown scored for P body formation\",\n      \"pmids\": [\"17936923\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not define which domains drive P body nucleation\", \"No biochemical demonstration of direct partner binding\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Resolved how PATL1 acts molecularly by showing it is a scaffold connecting deadenylation and decapping machineries, answering whether it merely resides in P bodies or actively drives decay.\",\n      \"evidence\": \"Reciprocal co-IP of Ccr4-Caf1-Not, Dcp1-Dcp2, Rck and Lsm1, domain deletion mapping, and tethering assays measuring deadenylation/decapping in HeLa cells\",\n      \"pmids\": [\"20584987\", \"20852261\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish target mRNA selectivity genome-wide\", \"Stepwise order of recruitment relative to Rck not yet defined\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Mapped the structural determinants of P body biogenesis to an N-terminal aggregation-prone domain that nucleates assembly and an acidic domain that controls foci size.\",\n      \"evidence\": \"Domain deletion/mutation analysis with P body formation readout in human cells\",\n      \"pmids\": [\"20584987\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis of the aggregation propensity not determined\", \"No in vitro reconstitution of nucleation\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Revealed an unanticipated nuclear life for PATL1, showing it shuttles via a CRM1-dependent NES and occupies distinct nuclear compartments, expanding its role beyond cytoplasmic decay.\",\n      \"evidence\": \"Leptomycin B and spliceostatin A treatment, immunofluorescence, and domain mapping of nuclear retention\",\n      \"pmids\": [\"22090346\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of nuclear localization not yet established\", \"Identity of nuclear binding partners undefined\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identified ALG-2 (PDCD6) as a Ca2+-dependent partner of PATL1, suggesting a link between calcium signaling and P body composition.\",\n      \"evidence\": \"In silico motif screening, Far-Western blotting, endogenous co-immunoprecipitation, and co-localization with DCP1A at P bodies\",\n      \"pmids\": [\"22437941\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No functional consequence of the PATL1-ALG-2 interaction established\", \"Calcium dependence of the interaction in cells not demonstrated\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Defined a stepwise P body assembly pathway, distinguishing Rck's translational suppression from PATL1's downstream role in triggering foci assembly and decapping.\",\n      \"evidence\": \"Interaction-deficient point mutations, co-IP, RNAi knockdown with rescue, tethering assays, and immunofluorescence\",\n      \"pmids\": [\"23535175\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinetics of the ordered assembly not directly measured\", \"Whether the order generalizes to all target mRNAs unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstrated that nuclear PATL1 forms a distinct Lsm2-8/U6 snRNA/SART3 complex in Cajal bodies and regulates alternative splicing, giving the nuclear pool a concrete mechanistic function.\",\n      \"evidence\": \"Reciprocal co-IP, immunofluorescence, RNAi depletion, and RNA sequencing for mRNA levels and splicing changes\",\n      \"pmids\": [\"28768202\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which PATL1 selects exons with weak donor sites unresolved\", \"Direct contact with splicing machinery vs. indirect effect not separated\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Connected PATL1 to transcriptional control by showing it binds TFIIE and promotes hERG expression, linking the protein to cardiomyocyte electrophysiology.\",\n      \"evidence\": \"C. elegans forward genetic screen, RNAi in SH-SY5Y and hiPSC-CMs, co-IP with TFIIE, dual-luciferase reporter, and electrophysiology\",\n      \"pmids\": [\"36608291\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"PATL1 and PATL2 contributions not always separated\", \"Whether TFIIE binding is direct and gene-selective mechanism unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How PATL1 partitions and is regulated between its cytoplasmic decay, nuclear splicing, and transcriptional roles, and what determines target selectivity in each, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No integrated regulatory model linking the three compartmental functions\", \"Signals controlling nucleocytoplasmic shuttling in vivo unknown\", \"Target specificity determinants for decay vs. splicing vs. transcription undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 6]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [4, 7]},\n      {\"term_id\": \"GO:0005730\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [1, 7]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [8]}\n    ],\n    \"complexes\": [\n      \"Lsm2-8/U6 snRNA/SART3 nuclear complex\",\n      \"P body\"\n    ],\n    \"partners\": [\n      \"DDX6\",\n      \"LSM1\",\n      \"DCP1A\",\n      \"DCP2\",\n      \"PDCD6\",\n      \"SART3\",\n      \"TFIIE\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":6,"faith_pct":83.33333333333333}}