{"gene":"PATL1","run_date":"2026-04-29T11:37:57","timeline":{"discoveries":[{"year":2007,"finding":"Human PATL1 (PatL1) localizes to processing bodies (P bodies) by co-localizing with P body components Lsm1, Rck/p54, and Dcp1, and its expression is required for P body formation.","method":"Fluorescence microscopy with tagged proteins; RNAi knockdown with P body marker co-localization","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 — direct localization experiment with functional consequence (P body loss on knockdown), single lab","pmids":["17936923"],"is_preprint":false},{"year":2010,"finding":"Human Pat1b (PATL1) 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 links deadenylation to decapping.","method":"Co-immunoprecipitation; tethering assay to reporter mRNA; domain mapping","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP with multiple complexes, tethering functional assay, domain dissection, replicated by multiple labs","pmids":["20584987"],"is_preprint":false},{"year":2010,"finding":"Pat1b (PATL1) strongly induces processing body formation; an N-terminal aggregation-prone domain nucleates P bodies, while an acidic domain controls P body size.","method":"Overexpression and domain deletion/mutation analysis with fluorescence microscopy","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 — domain-mapping with functional readout, highly cited, replicated","pmids":["20584987"],"is_preprint":false},{"year":2010,"finding":"Pat1b (PATL1) acts as an mRNA deadenylation factor: when tethered to a reporter mRNA, it represses gene expression by inducing deadenylation.","method":"Novel immunoprecipitation/mass spectrometry identification; mRNA tethering reporter assay in HeLa cells","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 — tethering functional assay demonstrating deadenylation, confirmed by IP-MS identification, two independent labs reporting same activity","pmids":["20852261","20584987"],"is_preprint":false},{"year":2011,"finding":"Pat1b (PATL1) is a nucleocytoplasmic shuttling protein whose nuclear export is mediated by a consensus NES sequence and the export receptor Crm1, as demonstrated by leptomycin B (LMB) sensitivity. In the nucleus, Pat1b localizes to PML-associated foci, SC35-containing splicing speckles (in a transcription-dependent manner), and nucleolar caps (in the absence of RNA synthesis), with retention in each compartment mediated by distinct protein regions.","method":"Leptomycin B treatment; immunofluorescence; domain mapping; spliceostatin A treatment","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal inhibitor experiments and domain mapping with clear functional compartment distinctions","pmids":["22090346"],"is_preprint":false},{"year":2012,"finding":"PATL1 interacts with ALG-2 (PDCD6), a Ca2+-binding 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 in P bodies.","method":"In silico screening; Far-Western blotting; co-immunoprecipitation with endogenous proteins; immunofluorescence microscopy","journal":"Journal of biochemistry","confidence":"Medium","confidence_rationale":"Tier 3 — single Co-IP with endogenous proteins plus far-Western, single lab, moderate evidence","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 (PATL1). Point mutations preventing Rck–Pat1b binding reveal that Pat1b assembles P bodies and suppresses tethered mRNA expression independently of Rck, while Rck requires the Pat1b-binding site to promote P body assembly and associate with Dcp2, Ago2, and TNRC6A. This defines a stepwise P body assembly: Rck suppresses mRNA translation first, then Pat1b triggers P body assembly and promotes decapping.","method":"Point mutagenesis; knockdown/rescue in HeLa cells; co-immunoprecipitation; mRNA tethering assay","journal":"RNA biology","confidence":"High","confidence_rationale":"Tier 2 — interaction-deficient mutants combined with functional rescue and multiple binding partner assays establish pathway order","pmids":["23535175"],"is_preprint":false},{"year":2017,"finding":"In addition to its cytoplasmic role with the Lsm1-7 heptamer in mRNA decay, Pat1b (PATL1) forms a nuclear complex with the Lsm2-8 heptamer that binds U6 snRNA and associates with SART3 and additional U4/U6.U5 tri-snRNP components in Cajal bodies. Pat1b depletion preferentially upregulates mRNAs with 3' UTR AU-rich elements (found in P bodies) and alters >180 alternative splicing events, characterized by skipping of regulated exons with weak donor sites.","method":"Co-immunoprecipitation; immunofluorescence; RNAi; RNA sequencing; interaction mapping","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP, RNAi with RNA-seq, multiple orthogonal methods in single study","pmids":["28768202"],"is_preprint":false},{"year":2023,"finding":"PATL1 (and PATL2) interact with TFIIE, a general transcription factor of the RNA polymerase II preinitiation complex, and facilitate transcription of hERG (KCNH2) mRNAs, as shown by dual-luciferase reporter assays. Knockdown of PATL1/PATL2 decreases hERG protein levels and current density in SH-SY5Y cells and hiPSC-derived cardiomyocytes, and prolongs action potential duration.","method":"Co-immunoprecipitation (PATL1–TFIIE); dual-luciferase reporter assay; siRNA knockdown; electrophysiology in hiPSC-CMs","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP plus functional reporter plus electrophysiology, but PATL1 and PATL2 not distinguished, single lab","pmids":["36608291"],"is_preprint":false}],"current_model":"Human PATL1 (Pat1b) is a multifunctional scaffold protein that coordinates cytoplasmic mRNA decay by physically linking the Ccr4-Caf1-Not deadenylation complex to the Dcp1-Dcp2 decapping complex via distinct domains, activates mRNA deadenylation and decapping when tethered to mRNA, nucleates processing body (P body) assembly through an N-terminal aggregation domain in a stepwise manner downstream of Rck-mediated translational repression, and also shuttles to the nucleus (via a CRM1-dependent NES) where it associates with the Lsm2-8/U6 snRNA/SART3 complex in Cajal bodies to participate in pre-mRNA splicing; additionally, PATL1 interacts with ALG-2 and TFIIE and can promote transcription of specific mRNAs such as hERG."},"narrative":{"teleology":[{"year":2007,"claim":"Establishing that PATL1 is a P body component whose presence is required for P body integrity answered the fundamental question of where PATL1 functions and identified it as a structural organizer of cytoplasmic mRNA granules.","evidence":"Fluorescence microscopy co-localization with Lsm1/Rck/Dcp1 and RNAi knockdown in human cells","pmids":["17936923"],"confidence":"Medium","gaps":["Single-lab observation at the time","Mechanism by which PATL1 loss dissolves P bodies unknown","Whether PATL1 is sufficient or only necessary for P body formation not tested"]},{"year":2010,"claim":"Demonstrating that PATL1 physically bridges deadenylation and decapping complexes through distinct domains, and that tethered PATL1 activates mRNA deadenylation and repression, established its molecular function as a scaffold coupling sequential steps of mRNA decay.","evidence":"Co-immunoprecipitation with Ccr4-Caf1-Not, Dcp1-Dcp2, Rck, and Lsm1; domain mapping; tethering reporter assays in HeLa cells; IP-MS identification","pmids":["20584987","20852261"],"confidence":"High","gaps":["Direct RNA-binding specificity of PATL1 not characterized","Whether PATL1 enhances decapping catalytic rate or substrate access unclear","Structural basis of multi-complex scaffold architecture unknown"]},{"year":2010,"claim":"Identifying an N-terminal aggregation-prone domain as the P body nucleation element and a separate acidic domain controlling P body size resolved how PATL1 organizes these condensates at a domain-level.","evidence":"Overexpression and domain deletion/mutation analysis with fluorescence microscopy","pmids":["20584987"],"confidence":"High","gaps":["Whether aggregation domain drives liquid-liquid phase separation or amyloid-like assembly not determined","Regulation of the aggregation domain (post-translational modifications, binding partners) unknown"]},{"year":2011,"claim":"Revealing that PATL1 shuttles between cytoplasm and nucleus via a CRM1-dependent NES and localizes to splicing speckles, PML bodies, and nucleolar caps uncovered a dual-compartment function beyond mRNA decay.","evidence":"Leptomycin B treatment, immunofluorescence, domain mapping, and spliceostatin A treatment in human cells","pmids":["22090346"],"confidence":"High","gaps":["Nuclear function at the molecular level not yet defined","Signals controlling nuclear import unknown","Functional significance of PML body and nucleolar cap association not tested"]},{"year":2012,"claim":"Identifying ALG-2 (PDCD6) as a calcium-dependent interactor of PATL1 in P bodies raised the possibility of calcium-regulated mRNA decay, linking signaling to P body biology.","evidence":"Far-Western blotting, co-immunoprecipitation of endogenous proteins, and immunofluorescence co-localization","pmids":["22437941"],"confidence":"Medium","gaps":["Single-lab Co-IP plus far-Western; no reciprocal validation or functional consequence shown","Whether calcium signaling modulates PATL1 activity or P body dynamics not tested","Stoichiometry and in vivo relevance unknown"]},{"year":2013,"claim":"Using interaction-deficient point mutants to show that Rck requires PATL1 binding for P body assembly while PATL1 acts independently of Rck established a stepwise model: Rck represses translation first, then PATL1 nucleates P bodies and promotes decapping.","evidence":"Point mutagenesis, knockdown/rescue, co-immunoprecipitation, and tethering assays in HeLa cells","pmids":["23535175"],"confidence":"High","gaps":["How translational repression by Rck is communicated to PATL1 recruitment is unclear","Whether other factors can substitute for Rck in the first step not tested"]},{"year":2017,"claim":"Demonstrating that PATL1 forms a nuclear complex with Lsm2-8, U6 snRNA, and SART3 in Cajal bodies and that its depletion alters >180 alternative splicing events defined PATL1's nuclear function in pre-mRNA splicing, complementing its cytoplasmic decay role.","evidence":"Reciprocal Co-IP, immunofluorescence, RNAi followed by RNA-seq in human cells","pmids":["28768202"],"confidence":"High","gaps":["Whether PATL1 directly modulates U4/U6 snRNP recycling or acts indirectly through Lsm2-8 unknown","How PATL1 selects regulated exons with weak donor sites not resolved","Relative contributions of cytoplasmic mRNA stabilization vs. nuclear splicing changes to the transcriptomic effects of PATL1 depletion unclear"]},{"year":2023,"claim":"Finding that PATL1 interacts with TFIIE and facilitates hERG mRNA transcription extended PATL1's function to transcriptional regulation, with physiological consequences for cardiac action potential duration.","evidence":"Co-immunoprecipitation (PATL1–TFIIE), dual-luciferase reporter assay, siRNA knockdown, and electrophysiology in SH-SY5Y cells and hiPSC-derived cardiomyocytes","pmids":["36608291"],"confidence":"Medium","gaps":["PATL1 and PATL2 contributions not individually resolved","Whether PATL1 acts as a general transcriptional cofactor or is specific to hERG/KCNH2 unknown","Single-lab finding not yet independently replicated"]},{"year":null,"claim":"The structural basis for PATL1's multi-domain scaffold function, the regulatory inputs controlling its nuclear-cytoplasmic partitioning, and whether its transcriptional role extends beyond hERG remain unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No high-resolution structure of PATL1 or its complexes","Post-translational modifications regulating PATL1 activity or localization not characterized","Genome-wide identification of PATL1 direct mRNA targets not performed"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,6]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[8]}],"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:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[4,7]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[1,3,7]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[8]}],"complexes":["Lsm1-7-Pat1b complex","Lsm2-8-Pat1b-SART3 nuclear complex"],"partners":["DCP1A","DCP2","DDX6","CNOT1","LSM1","SART3","PDCD6","GTF2E1"],"other_free_text":[]},"mechanistic_narrative":"PATL1 (Pat1b) is a multifunctional scaffold protein that coordinates cytoplasmic mRNA decay and processing body (P body) assembly while also participating in nuclear RNA metabolism. In the cytoplasm, PATL1 physically bridges the Ccr4-Caf1-Not deadenylation complex and the Dcp1-Dcp2 decapping complex via distinct domains, directly activating mRNA deadenylation and decapping when tethered to mRNA, and nucleates P body formation through an N-terminal aggregation domain in a stepwise pathway downstream of Rck-mediated translational repression [PMID:20584987, PMID:23535175]. PATL1 is a CRM1-dependent nucleocytoplasmic shuttling protein that, in the nucleus, associates with the Lsm2-8/U6 snRNA/SART3 complex in Cajal bodies and regulates alternative splicing of exons with weak splice donors; its depletion also preferentially stabilizes AU-rich element-containing mRNAs [PMID:28768202, PMID:22090346]. PATL1 additionally interacts with TFIIE and facilitates transcription of specific mRNAs including hERG (KCNH2), linking it to cardiac electrophysiology [PMID:36608291]."},"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":"30124909","id":"PMC_30124909","title":"AtCaM4 interacts with a Sec14-like protein, PATL1, to regulate freezing tolerance in Arabidopsis in a CBF-independent manner.","date":"2018","source":"Journal of experimental botany","url":"https://pubmed.ncbi.nlm.nih.gov/30124909","citation_count":47,"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":34,"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":28,"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":4,"is_preprint":false},{"pmid":"42001297","id":"PMC_42001297","title":"The Arabidopsis thaliana PATL1 functions downstream of CaM3 to mediate vesicle trafficking under the heat shock pathway.","date":"2026","source":"The Plant journal : for cell and molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/42001297","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.05.06.652549","title":"Expression of Arabidopsis Extracellular Vesicle Protein Markers in <i>Nicotiana benthamiana</i> Reveals Distinct Vesicle Subpopulations","date":"2025-05-10","source":"bioRxiv","url":"https://doi.org/10.1101/2025.05.06.652549","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":6540,"output_tokens":2289,"usd":0.026978},"stage2":{"model":"claude-opus-4-6","input_tokens":5586,"output_tokens":2442,"usd":0.13347},"total_usd":0.160448,"stage1_batch_id":"msgbatch_012ZiiCUBfB62NCTQd4Bk1Jo","stage2_batch_id":"msgbatch_01Xuqq9aUHoQouS7UVGZNStZ","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2007,\n      \"finding\": \"Human PATL1 (PatL1) localizes to processing bodies (P bodies) by co-localizing with P body components Lsm1, Rck/p54, and Dcp1, and its expression is required for P body formation.\",\n      \"method\": \"Fluorescence microscopy with tagged proteins; RNAi knockdown with P body marker co-localization\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct localization experiment with functional consequence (P body loss on knockdown), single lab\",\n      \"pmids\": [\"17936923\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Human Pat1b (PATL1) 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 links deadenylation to decapping.\",\n      \"method\": \"Co-immunoprecipitation; tethering assay to reporter mRNA; domain mapping\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP with multiple complexes, tethering functional assay, domain dissection, replicated by multiple labs\",\n      \"pmids\": [\"20584987\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Pat1b (PATL1) strongly induces processing body formation; an N-terminal aggregation-prone domain nucleates P bodies, while an acidic domain controls P body size.\",\n      \"method\": \"Overexpression and domain deletion/mutation analysis with fluorescence microscopy\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — domain-mapping with functional readout, highly cited, replicated\",\n      \"pmids\": [\"20584987\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Pat1b (PATL1) acts as an mRNA deadenylation factor: when tethered to a reporter mRNA, it represses gene expression by inducing deadenylation.\",\n      \"method\": \"Novel immunoprecipitation/mass spectrometry identification; mRNA tethering reporter assay in HeLa cells\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — tethering functional assay demonstrating deadenylation, confirmed by IP-MS identification, two independent labs reporting same activity\",\n      \"pmids\": [\"20852261\", \"20584987\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Pat1b (PATL1) is a nucleocytoplasmic shuttling protein whose nuclear export is mediated by a consensus NES sequence and the export receptor Crm1, as demonstrated by leptomycin B (LMB) sensitivity. In the nucleus, Pat1b localizes to PML-associated foci, SC35-containing splicing speckles (in a transcription-dependent manner), and nucleolar caps (in the absence of RNA synthesis), with retention in each compartment mediated by distinct protein regions.\",\n      \"method\": \"Leptomycin B treatment; immunofluorescence; domain mapping; spliceostatin A treatment\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal inhibitor experiments and domain mapping with clear functional compartment distinctions\",\n      \"pmids\": [\"22090346\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PATL1 interacts with ALG-2 (PDCD6), a Ca2+-binding 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 in P bodies.\",\n      \"method\": \"In silico screening; Far-Western blotting; co-immunoprecipitation with endogenous proteins; immunofluorescence microscopy\",\n      \"journal\": \"Journal of biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single Co-IP with endogenous proteins plus far-Western, single lab, moderate evidence\",\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 (PATL1). Point mutations preventing Rck–Pat1b binding reveal that Pat1b assembles P bodies and suppresses tethered mRNA expression independently of Rck, while Rck requires the Pat1b-binding site to promote P body assembly and associate with Dcp2, Ago2, and TNRC6A. This defines a stepwise P body assembly: Rck suppresses mRNA translation first, then Pat1b triggers P body assembly and promotes decapping.\",\n      \"method\": \"Point mutagenesis; knockdown/rescue in HeLa cells; co-immunoprecipitation; mRNA tethering assay\",\n      \"journal\": \"RNA biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — interaction-deficient mutants combined with functional rescue and multiple binding partner assays establish pathway order\",\n      \"pmids\": [\"23535175\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In addition to its cytoplasmic role with the Lsm1-7 heptamer in mRNA decay, Pat1b (PATL1) forms a nuclear complex with the Lsm2-8 heptamer that binds U6 snRNA and associates with SART3 and additional U4/U6.U5 tri-snRNP components in Cajal bodies. Pat1b depletion preferentially upregulates mRNAs with 3' UTR AU-rich elements (found in P bodies) and alters >180 alternative splicing events, characterized by skipping of regulated exons with weak donor sites.\",\n      \"method\": \"Co-immunoprecipitation; immunofluorescence; RNAi; RNA sequencing; interaction mapping\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP, RNAi with RNA-seq, multiple orthogonal methods in single 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 of the RNA polymerase II preinitiation complex, and facilitate transcription of hERG (KCNH2) mRNAs, as shown by dual-luciferase reporter assays. Knockdown of PATL1/PATL2 decreases hERG protein levels and current density in SH-SY5Y cells and hiPSC-derived cardiomyocytes, and prolongs action potential duration.\",\n      \"method\": \"Co-immunoprecipitation (PATL1–TFIIE); dual-luciferase reporter assay; siRNA knockdown; electrophysiology in hiPSC-CMs\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus functional reporter plus electrophysiology, but PATL1 and PATL2 not distinguished, single lab\",\n      \"pmids\": [\"36608291\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"Human PATL1 (Pat1b) is a multifunctional scaffold protein that coordinates cytoplasmic mRNA decay by physically linking the Ccr4-Caf1-Not deadenylation complex to the Dcp1-Dcp2 decapping complex via distinct domains, activates mRNA deadenylation and decapping when tethered to mRNA, nucleates processing body (P body) assembly through an N-terminal aggregation domain in a stepwise manner downstream of Rck-mediated translational repression, and also shuttles to the nucleus (via a CRM1-dependent NES) where it associates with the Lsm2-8/U6 snRNA/SART3 complex in Cajal bodies to participate in pre-mRNA splicing; additionally, PATL1 interacts with ALG-2 and TFIIE and can promote transcription of specific mRNAs such as hERG.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"PATL1 (Pat1b) is a multifunctional scaffold protein that coordinates cytoplasmic mRNA decay and processing body (P body) assembly while also participating in nuclear RNA metabolism. In the cytoplasm, PATL1 physically bridges the Ccr4-Caf1-Not deadenylation complex and the Dcp1-Dcp2 decapping complex via distinct domains, directly activating mRNA deadenylation and decapping when tethered to mRNA, and nucleates P body formation through an N-terminal aggregation domain in a stepwise pathway downstream of Rck-mediated translational repression [PMID:20584987, PMID:23535175]. PATL1 is a CRM1-dependent nucleocytoplasmic shuttling protein that, in the nucleus, associates with the Lsm2-8/U6 snRNA/SART3 complex in Cajal bodies and regulates alternative splicing of exons with weak splice donors; its depletion also preferentially stabilizes AU-rich element-containing mRNAs [PMID:28768202, PMID:22090346]. PATL1 additionally interacts with TFIIE and facilitates transcription of specific mRNAs including hERG (KCNH2), linking it to cardiac electrophysiology [PMID:36608291].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Establishing that PATL1 is a P body component whose presence is required for P body integrity answered the fundamental question of where PATL1 functions and identified it as a structural organizer of cytoplasmic mRNA granules.\",\n      \"evidence\": \"Fluorescence microscopy co-localization with Lsm1/Rck/Dcp1 and RNAi knockdown in human cells\",\n      \"pmids\": [\"17936923\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab observation at the time\", \"Mechanism by which PATL1 loss dissolves P bodies unknown\", \"Whether PATL1 is sufficient or only necessary for P body formation not tested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Demonstrating that PATL1 physically bridges deadenylation and decapping complexes through distinct domains, and that tethered PATL1 activates mRNA deadenylation and repression, established its molecular function as a scaffold coupling sequential steps of mRNA decay.\",\n      \"evidence\": \"Co-immunoprecipitation with Ccr4-Caf1-Not, Dcp1-Dcp2, Rck, and Lsm1; domain mapping; tethering reporter assays in HeLa cells; IP-MS identification\",\n      \"pmids\": [\"20584987\", \"20852261\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct RNA-binding specificity of PATL1 not characterized\", \"Whether PATL1 enhances decapping catalytic rate or substrate access unclear\", \"Structural basis of multi-complex scaffold architecture unknown\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identifying an N-terminal aggregation-prone domain as the P body nucleation element and a separate acidic domain controlling P body size resolved how PATL1 organizes these condensates at a domain-level.\",\n      \"evidence\": \"Overexpression and domain deletion/mutation analysis with fluorescence microscopy\",\n      \"pmids\": [\"20584987\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether aggregation domain drives liquid-liquid phase separation or amyloid-like assembly not determined\", \"Regulation of the aggregation domain (post-translational modifications, binding partners) unknown\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Revealing that PATL1 shuttles between cytoplasm and nucleus via a CRM1-dependent NES and localizes to splicing speckles, PML bodies, and nucleolar caps uncovered a dual-compartment function beyond mRNA decay.\",\n      \"evidence\": \"Leptomycin B treatment, immunofluorescence, domain mapping, and spliceostatin A treatment in human cells\",\n      \"pmids\": [\"22090346\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Nuclear function at the molecular level not yet defined\", \"Signals controlling nuclear import unknown\", \"Functional significance of PML body and nucleolar cap association not tested\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identifying ALG-2 (PDCD6) as a calcium-dependent interactor of PATL1 in P bodies raised the possibility of calcium-regulated mRNA decay, linking signaling to P body biology.\",\n      \"evidence\": \"Far-Western blotting, co-immunoprecipitation of endogenous proteins, and immunofluorescence co-localization\",\n      \"pmids\": [\"22437941\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab Co-IP plus far-Western; no reciprocal validation or functional consequence shown\", \"Whether calcium signaling modulates PATL1 activity or P body dynamics not tested\", \"Stoichiometry and in vivo relevance unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Using interaction-deficient point mutants to show that Rck requires PATL1 binding for P body assembly while PATL1 acts independently of Rck established a stepwise model: Rck represses translation first, then PATL1 nucleates P bodies and promotes decapping.\",\n      \"evidence\": \"Point mutagenesis, knockdown/rescue, co-immunoprecipitation, and tethering assays in HeLa cells\",\n      \"pmids\": [\"23535175\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How translational repression by Rck is communicated to PATL1 recruitment is unclear\", \"Whether other factors can substitute for Rck in the first step not tested\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstrating that PATL1 forms a nuclear complex with Lsm2-8, U6 snRNA, and SART3 in Cajal bodies and that its depletion alters >180 alternative splicing events defined PATL1's nuclear function in pre-mRNA splicing, complementing its cytoplasmic decay role.\",\n      \"evidence\": \"Reciprocal Co-IP, immunofluorescence, RNAi followed by RNA-seq in human cells\",\n      \"pmids\": [\"28768202\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PATL1 directly modulates U4/U6 snRNP recycling or acts indirectly through Lsm2-8 unknown\", \"How PATL1 selects regulated exons with weak donor sites not resolved\", \"Relative contributions of cytoplasmic mRNA stabilization vs. nuclear splicing changes to the transcriptomic effects of PATL1 depletion unclear\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Finding that PATL1 interacts with TFIIE and facilitates hERG mRNA transcription extended PATL1's function to transcriptional regulation, with physiological consequences for cardiac action potential duration.\",\n      \"evidence\": \"Co-immunoprecipitation (PATL1–TFIIE), dual-luciferase reporter assay, siRNA knockdown, and electrophysiology in SH-SY5Y cells and hiPSC-derived cardiomyocytes\",\n      \"pmids\": [\"36608291\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"PATL1 and PATL2 contributions not individually resolved\", \"Whether PATL1 acts as a general transcriptional cofactor or is specific to hERG/KCNH2 unknown\", \"Single-lab finding not yet independently replicated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The structural basis for PATL1's multi-domain scaffold function, the regulatory inputs controlling its nuclear-cytoplasmic partitioning, and whether its transcriptional role extends beyond hERG remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No high-resolution structure of PATL1 or its complexes\", \"Post-translational modifications regulating PATL1 activity or localization not characterized\", \"Genome-wide identification of PATL1 direct mRNA targets not performed\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 6]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [8]}\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:0005654\", \"supporting_discovery_ids\": [4, 7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [1, 3, 7]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [8]}\n    ],\n    \"complexes\": [\n      \"Lsm1-7-Pat1b complex\",\n      \"Lsm2-8-Pat1b-SART3 nuclear complex\"\n    ],\n    \"partners\": [\n      \"DCP1A\",\n      \"DCP2\",\n      \"DDX6\",\n      \"CNOT1\",\n      \"LSM1\",\n      \"SART3\",\n      \"PDCD6\",\n      \"GTF2E1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}