{"gene":"LSM4","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":2001,"finding":"Human LSM4 contains symmetrically dimethylated arginine (sDMA) residues in vivo, as determined by mass spectrometry and protein sequencing. This symmetrical dimethylation is required for binding of LSM4 to the Tudor domain of the SMN protein; inhibition of dimethylation by S-adenosylhomocysteine abolished LSM4-SMN Tudor interaction. The PRMT responsible is cytoplasmic.","method":"Mass spectrometry, protein sequencing, in vitro methylation assay with HeLa cytosolic and nuclear extracts, synthetic peptide competition assay","journal":"RNA (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1 / Strong — mass spectrometry identification of modification, in vitro methylation reconstitution, peptide inhibition experiments, multiple orthogonal methods in one rigorous study","pmids":["11720283"],"is_preprint":false},{"year":2016,"finding":"The C-terminal RGG domain of human LSM4 promotes Processing Body (PB) accumulation in human cells. Symmetric dimethylation of arginines within the RGG domain by PRMT5 stimulates PB formation. An RGG-deleted LSM4 mutant failed to rescue PB formation in cells depleted of endogenous LSM4, although it retained the ability to assemble into the Lsm1-7 complex, associate with decapping factors, and promote mRNA decay and translational repression. The HAT1-RBBP7 acetyltransferase complex was identified as an interaction partner of the Lsm4 RGG domain, but no role for this complex in PB metabolism was found.","method":"RNAi depletion of endogenous LSM4 with re-expression of deletion mutants, PRMT5 depletion, Co-immunoprecipitation, mRNA decay and translational repression assays, fluorescence microscopy of PBs","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal functional rescue, multiple deletion mutants, depletion of writer enzyme (PRMT5), several orthogonal readouts in a single thorough study","pmids":["27247266"],"is_preprint":false},{"year":2013,"finding":"The C-terminal extension of Lsm4 (beyond the Sm domain) directly interacts with both SLBP and 3'hExo on the histone mRNP. Mutations in the C-terminal tail of Lsm4 that prevent SLBP and 3'hExo binding reduce the rate of histone mRNA degradation when DNA synthesis is inhibited.","method":"Direct binding assays (pulldown/co-immunoprecipitation), site-directed mutagenesis of C-terminal tail, histone mRNA decay assays in mammalian cells","journal":"RNA (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — direct binding assay, mutagenesis with functional decay readout, two orthogonal methods in single study","pmids":["24255165"],"is_preprint":false},{"year":2012,"finding":"Crystal structures of S. pombe Lsm4 (and Lsm3, Lsm5/6/7) were solved, revealing a conserved Sm fold. In the crystal lattice Lsm4 forms a trimer; analytical ultracentrifugation showed Lsm4 undergoes a dynamic equilibrium between monomer and trimer in solution. No RNA binding was detected for Lsm4 alone in RNA binding assays with oligo(U).","method":"X-ray crystallography, analytical ultracentrifugation, RNA binding assays","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure determination plus solution AUC and direct RNA binding assay, single study with orthogonal structural and biochemical methods","pmids":["22615807"],"is_preprint":false},{"year":2005,"finding":"ICln (a multifunctional protein involved in cell volume regulation and RNA splicing) interacts with LSM4 via its PH domain-like fold, suggesting the ICln PH domain serves as a protein-protein interaction platform linking membrane physiology and RNA processing.","method":"Protein interaction assay (pulldown/binding assay) with truncated ICln159 mutant and LSM4; structural determination of ICln159 by NMR/crystallography","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — interaction demonstrated but by single pulldown/binding assay; structural context adds support but LSM4-specific mechanism minimally characterized","pmids":["15905169"],"is_preprint":false},{"year":2008,"finding":"In isotonic conditions, LSM4 associates with the plasma membrane and with ICln (shown by FRET and biochemistry). Hypotonic cell swelling causes dissociation of LSM4 from both the plasma membrane and from ICln. Overexpression of LSM4 inhibits activation kinetics and current density of the swelling-dependent anion channel IClswell, establishing LSM4 as a co-factor in regulatory volume decrease in NIH3T3 and HEK293 cells.","method":"FRET, biochemical fractionation, electrophysiology, overexpression of LSM4","journal":"Cellular physiology and biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — FRET plus biochemistry plus electrophysiology, single lab but three orthogonal methods","pmids":["19088440"],"is_preprint":false},{"year":2000,"finding":"Disruption of the mLsm4 gene in mice causes peri-implantation lethality: null blastocysts implant but die shortly thereafter, establishing that Lsm4 is an essential gene in mammals. The early lethality indicates its role in splicing cannot be compensated by other Lsm proteins.","method":"Promoter trap gene targeting in murine ES cells, homozygous knockout mouse analysis","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean knockout with defined lethal phenotype, genetic loss-of-function with clear developmental readout","pmids":["10629062"],"is_preprint":false},{"year":2001,"finding":"In K. lactis and S. cerevisiae, the N-terminal 72 amino acids of KlLsm4p containing the Sm-like domains are sufficient to restore cell viability in cells lacking the wild-type protein, but deletion of the carboxy-terminal region results in loss of viability in stationary phase.","method":"Complementation assay in K. lactis and S. cerevisiae lsm4 deletion mutants with truncated KlLsm4 constructs","journal":"Yeast (Chichester, England)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic complementation with defined domain deletions in two yeast species, clear functional readout","pmids":["11561292"],"is_preprint":false},{"year":2016,"finding":"In S. cerevisiae, combined deletion of EDC3 and the Q/N-rich C-terminal domain of Lsm4 (edc3Δ lsm4ΔC double mutant) reduces mRNA stability and increases dependence on Ccr4-mediated deadenylation and decapping. The decapping enzyme catalytic subunit Dcp2 accumulates in the nucleus in this double mutant.","method":"Genetic double mutant analysis in yeast, mRNA stability measurements, epistasis with mRNA decay pathway components, localization of Dcp2","journal":"Biology open","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with defined double mutant, multiple mRNA stability readouts and localization, single lab","pmids":["27543059"],"is_preprint":false},{"year":2013,"finding":"Overexpression of the Q/N-rich region of yeast Lsm4 eliminates the prions [PSI+], [URE3], and [RNQ+]. Lsm4 forms an amyloid in vivo, and fluorescence correlation spectroscopy showed that during Lsm4-driven [PSI+] elimination, [PSI+] aggregates increase in size before forming foci in mother cells.","method":"Overexpression of Lsm4 and subcloning of Q/N-rich region in S. cerevisiae, fluorescence correlation spectroscopy, amyloid detection in vivo","journal":"MicrobiologyOpen","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo amyloid formation, FCS, domain mapping by subcloning, single lab with multiple readouts","pmids":["23512891"],"is_preprint":false},{"year":2023,"finding":"Purified full-length human LSM4 protein undergoes concentration-dependent liquid-liquid phase separation (LLPS) in vitro. The C-terminus of LSM4 contains a low-complexity domain predicted to drive LLPS. High salt concentrations and 1,6-hexanediol block LSM4-induced LLPS, and fusion of LSM4 droplets is observed in vitro.","method":"In vitro purification from E. coli, wide-field fluorescence microscopy, 1,6-hexanediol and salt sensitivity assays, bioinformatic disorder prediction","journal":"Molekuliarnaia biologiia","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — direct in vitro reconstitution of LLPS, but single lab, no mutagenesis validation, no cellular functional consequence demonstrated","pmids":["36976747"],"is_preprint":false},{"year":2025,"finding":"tRF-31 (a tRNA-derived small RNA) binds directly to LSM4 under normoxic conditions. Under hypoxia, reduced tRF-31 leads to decreased ubiquitination of LSM4, enhancing its protein stability. Stabilized LSM4 translocates to the nucleus and promotes splicing of EDN1 pre-mRNA, driving proliferation of pulmonary artery endothelial cells.","method":"Binding assay (tRF-31–LSM4 interaction), ubiquitination assay, nuclear fractionation, RNA splicing analysis, overexpression and knockdown in PAECs","journal":"European journal of pharmacology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — multiple methods (binding, ubiquitination, localization, splicing), but single lab and limited mechanistic controls for each step","pmids":["41354297"],"is_preprint":false},{"year":2024,"finding":"SF3B4 physically interacts with LSM4 (shown by Co-IP), and SF3B4 knockdown-mediated inhibition of NSCLC cell functions is rescued by LSM4 overexpression, placing LSM4 downstream of SF3B4 in a pathway promoting lung cancer cell growth, metastasis, and stemness.","method":"Co-immunoprecipitation (Co-IP), RIP, MeRIP, cell functional rescue assays, xenograft mouse models","journal":"Thoracic cancer","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP for interaction, rescue experiment with LSM4 overexpression is phenotypic only, no defined molecular mechanism for LSM4 activity","pmids":["38462740"],"is_preprint":false}],"current_model":"LSM4 is an essential Sm-like protein that assembles into the cytoplasmic Lsm1-7 complex to promote mRNA decapping and decay; its C-terminal extension (RGG domain in humans, Q/N-rich in yeast) drives Processing Body (P-body) formation through liquid-liquid phase separation stimulated by PRMT5-mediated symmetric arginine dimethylation, while the same C-terminal tail directly contacts SLBP and 3'hExo on histone mRNPs to facilitate histone mRNA degradation; symmetrical dimethylation of LSM4 arginines also mediates binding to the SMN Tudor domain, linking LSM4 to snRNP biogenesis; and under hypoxic conditions LSM4 stability is regulated by ubiquitination, with stabilized LSM4 translocating to the nucleus to influence pre-mRNA splicing."},"narrative":{"mechanistic_narrative":"LSM4 is an essential Sm-like protein that, beyond its conserved Sm-fold core, uses a C-terminal extension to organize cytoplasmic mRNA decay and Processing Body (PB) assembly [PMID:27247266, PMID:22615807]. The Sm domain adopts the canonical Lsm fold and exists in a dynamic monomer–trimer equilibrium, but does not bind oligo(U) RNA on its own, consistent with function within the assembled Lsm1-7 complex rather than as an isolated subunit [PMID:22615807]. The C-terminal RGG domain is dispensable for Lsm1-7 assembly, decapping-factor association, and bulk mRNA decay yet is required to drive PB accumulation, an activity stimulated by PRMT5-catalyzed symmetric arginine dimethylation of the RGG residues [PMID:27247266]; purified full-length LSM4 phase-separates in vitro through its low-complexity C-terminus, providing a biophysical basis for this PB-scaffolding role [PMID:36976747]. Symmetric dimethylation of LSM4 arginines also creates the binding determinant for the SMN Tudor domain, linking LSM4 to snRNP biogenesis machinery [PMID:11720283]. The same C-terminal tail directly contacts SLBP and 3'hExo on histone mRNPs and is required for efficient histone mRNA degradation when DNA synthesis is blocked [PMID:24255165]. Genetically, LSM4 is essential in mammals: null mouse blastocysts implant but die peri-implantation, a lethality the early embryo cannot compensate with other Lsm proteins [PMID:10629062], and in yeast the Sm-like core suffices for viability while the Q/N-rich C-terminal region is needed for stationary-phase survival and contributes to mRNA stability together with EDC3 [PMID:11561292, PMID:27543059]. LSM4 stability is further controlled by ubiquitination: under hypoxia, loss of the tRNA-derived fragment tRF-31 reduces LSM4 ubiquitination, stabilizing the protein and promoting its nuclear translocation to drive EDN1 pre-mRNA splicing [PMID:41354297].","teleology":[{"year":2000,"claim":"Establishing whether LSM4 is genetically essential in mammals defined its non-redundant importance in early development.","evidence":"Promoter-trap gene targeting and homozygous knockout analysis in mice","pmids":["10629062"],"confidence":"High","gaps":["Does not identify which molecular function (splicing vs decay) is the lethal deficit","No conditional or tissue-specific dissection"]},{"year":2001,"claim":"Identifying symmetric arginine dimethylation on LSM4 and its requirement for SMN Tudor binding connected LSM4 to the snRNP biogenesis machinery.","evidence":"Mass spectrometry, in vitro methylation with HeLa extracts, and peptide competition assays","pmids":["11720283"],"confidence":"High","gaps":["The specific cytoplasmic PRMT was not identified at this stage","Functional consequence of SMN binding for LSM4 not measured"]},{"year":2001,"claim":"Domain dissection in yeast separated the essential Sm-like core from the C-terminal region required only under stationary-phase stress.","evidence":"Complementation of lsm4 deletion mutants in K. lactis and S. cerevisiae with truncated constructs","pmids":["11561292"],"confidence":"Medium","gaps":["Molecular reason for stationary-phase requirement not defined","Yeast result may not map directly onto mammalian RGG functions"]},{"year":2005,"claim":"Identifying ICln as an LSM4 partner via its PH-like fold hinted at a link between LSM4 and membrane/volume physiology.","evidence":"Pulldown/binding assay with truncated ICln159 plus structural determination","pmids":["15905169"],"confidence":"Medium","gaps":["Single binding assay without reciprocal validation","Cellular significance not tested in this study"]},{"year":2008,"claim":"Functional electrophysiology placed LSM4 as a co-factor in regulatory volume decrease, extending its role beyond RNA metabolism.","evidence":"FRET, biochemical fractionation, and electrophysiology with LSM4 overexpression in NIH3T3/HEK293","pmids":["19088440"],"confidence":"Medium","gaps":["Mechanism linking an mRNA-decay protein to anion channels unresolved","Reliance on overexpression"]},{"year":2012,"claim":"Crystal structures and solution analysis defined the LSM4 Sm fold and showed it does not bind RNA alone, framing LSM4 as a complex-dependent subunit.","evidence":"X-ray crystallography of S. pombe Lsm4, analytical ultracentrifugation, and oligo(U) binding assays","pmids":["22615807"],"confidence":"High","gaps":["No structure of the C-terminal extension","Functional meaning of the monomer–trimer equilibrium unclear"]},{"year":2013,"claim":"Mapping direct LSM4 C-terminal contacts to SLBP and 3'hExo explained how LSM4 participates in regulated histone mRNA degradation.","evidence":"Direct binding assays and C-terminal mutagenesis with histone mRNA decay readouts in mammalian cells","pmids":["24255165"],"confidence":"High","gaps":["Whether dimethylation modulates these contacts not tested","Structural basis of the SLBP/3'hExo interface unknown"]},{"year":2013,"claim":"Demonstrating that the Lsm4 Q/N-rich region forms amyloid and antagonizes prions revealed an intrinsic aggregation propensity of the C-terminal tail.","evidence":"Overexpression and subcloning in S. cerevisiae, fluorescence correlation spectroscopy, in vivo amyloid detection","pmids":["23512891"],"confidence":"Medium","gaps":["Relationship between amyloid behavior and physiological PB assembly not established","Single-lab, overexpression-based"]},{"year":2016,"claim":"Reciprocal rescue with deletion mutants separated PB assembly from decay and pinned PB formation on PRMT5-modified RGG residues.","evidence":"RNAi/re-expression of LSM4 mutants, PRMT5 depletion, Co-IP, decay/translational repression assays, and PB microscopy","pmids":["27247266"],"confidence":"High","gaps":["Functional role of the HAT1-RBBP7 interaction unresolved","How PB loss affects mRNA fate not detailed"]},{"year":2016,"claim":"Yeast epistasis showed the Q/N-rich C-terminus and EDC3 jointly support mRNA stability and proper decapping-enzyme localization.","evidence":"edc3Δ lsm4ΔC double mutant analysis with mRNA stability, decay-pathway epistasis, and Dcp2 localization","pmids":["27543059"],"confidence":"Medium","gaps":["Mechanism of nuclear Dcp2 accumulation unexplained","Direct vs indirect contribution of Lsm4 C-terminus unclear"]},{"year":2023,"claim":"In vitro reconstitution showed full-length LSM4 undergoes concentration-dependent LLPS, providing a biophysical basis for its PB-scaffolding activity.","evidence":"Purified LSM4 with fluorescence microscopy, hexanediol/salt sensitivity, and disorder prediction","pmids":["36976747"],"confidence":"Medium","gaps":["No mutagenesis linking LLPS to specific residues","No cellular functional consequence demonstrated"]},{"year":2024,"claim":"An SF3B4–LSM4 interaction was placed in a lung-cancer growth pathway with LSM4 acting downstream of SF3B4.","evidence":"Co-IP, RIP/MeRIP, rescue assays, and xenograft models in NSCLC","pmids":["38462740"],"confidence":"Low","gaps":["Single Co-IP without reciprocal validation","Rescue is phenotypic with no defined molecular activity for LSM4"]},{"year":2025,"claim":"Linking tRF-31 binding to LSM4 ubiquitination and nuclear translocation revealed a hypoxia-responsive control of LSM4 stability and splicing output.","evidence":"Binding and ubiquitination assays, nuclear fractionation, and EDN1 splicing analysis in pulmonary artery endothelial cells","pmids":["41354297"],"confidence":"Medium","gaps":["The ubiquitin ligase responsible is not identified","How tRF-31 binding mechanistically promotes ubiquitination unclear","Single-lab with limited per-step controls"]},{"year":null,"claim":"How LSM4's cytoplasmic decay/PB roles, its modification-dependent SMN/snRNP links, and its hypoxia-induced nuclear splicing function are integrated into a single regulatory logic remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model coupling LSM4 dimethylation, ubiquitination, and subcellular partitioning","Structural basis of the C-terminal extension and its partner interfaces undetermined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[3,11]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[3]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,2]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1,10]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[11]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[5]}],"pathway":[],"complexes":["Lsm1-7 complex"],"partners":["SMN","PRMT5","SLBP","3'HEXO","ICLN","SF3B4","EDC3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9Y4Z0","full_name":"U6 snRNA-associated Sm-like protein LSm4","aliases":["Glycine-rich protein","GRP"],"length_aa":139,"mass_kda":15.3,"function":"Plays a role in pre-mRNA splicing as component of the U4/U6-U5 tri-snRNP complex that is involved in spliceosome assembly, and as component of the precatalytic spliceosome (spliceosome B complex) (PubMed:28781166). The heptameric LSM2-8 complex binds specifically to the 3'-terminal U-tract of U6 snRNA (PubMed:10523320)","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q9Y4Z0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/LSM4","classification":"Common Essential","n_dependent_lines":1202,"n_total_lines":1208,"dependency_fraction":0.9950331125827815},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CLNS1A","stoichiometry":0.2},{"gene":"CLTA","stoichiometry":0.2},{"gene":"CLTB","stoichiometry":0.2},{"gene":"CPSF6","stoichiometry":0.2},{"gene":"PRPF4B","stoichiometry":0.2},{"gene":"RBM39","stoichiometry":0.2},{"gene":"RBM42","stoichiometry":0.2},{"gene":"SF3A1","stoichiometry":0.2},{"gene":"SF3A2","stoichiometry":0.2},{"gene":"SF3B1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/LSM4","total_profiled":1310},"omim":[{"mim_id":"607288","title":"LSM8 PROTEIN; LSM8","url":"https://www.omim.org/entry/607288"},{"mim_id":"607287","title":"LSM7 PROTEIN; LSM7","url":"https://www.omim.org/entry/607287"},{"mim_id":"607286","title":"LSM6 PROTEIN; LSM6","url":"https://www.omim.org/entry/607286"},{"mim_id":"607285","title":"LSM5 PROTEIN; LSM5","url":"https://www.omim.org/entry/607285"},{"mim_id":"607284","title":"LSM4 PROTEIN; LSM4","url":"https://www.omim.org/entry/607284"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Vesicles","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/LSM4"},"hgnc":{"alias_symbol":["YER112W"],"prev_symbol":[]},"alphafold":{"accession":"Q9Y4Z0","domains":[{"cath_id":"2.30.30.100","chopping":"2-87","consensus_level":"high","plddt":94.7445,"start":2,"end":87}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y4Z0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y4Z0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y4Z0-F1-predicted_aligned_error_v6.png","plddt_mean":75.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=LSM4","jax_strain_url":"https://www.jax.org/strain/search?query=LSM4"},"sequence":{"accession":"Q9Y4Z0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9Y4Z0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9Y4Z0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y4Z0"}},"corpus_meta":[{"pmid":"11720283","id":"PMC_11720283","title":"Symmetrical dimethylation of arginine residues in spliceosomal Sm protein B/B' and the Sm-like protein LSm4, and their interaction with the SMN protein.","date":"2001","source":"RNA (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/11720283","citation_count":314,"is_preprint":false},{"pmid":"33285422","id":"PMC_33285422","title":"Circ_0025033 promotes the progression of ovarian cancer by activating the expression of LSM4 via targeting miR-184.","date":"2020","source":"Pathology, research and practice","url":"https://pubmed.ncbi.nlm.nih.gov/33285422","citation_count":60,"is_preprint":false},{"pmid":"27247266","id":"PMC_27247266","title":"The C-Terminal RGG Domain of Human Lsm4 Promotes Processing Body Formation Stimulated by Arginine Dimethylation.","date":"2016","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/27247266","citation_count":48,"is_preprint":false},{"pmid":"15905169","id":"PMC_15905169","title":"ICln159 folds into a pleckstrin homology domain-like structure. Interaction with kinases and the splicing factor LSm4.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15905169","citation_count":32,"is_preprint":false},{"pmid":"24255165","id":"PMC_24255165","title":"The C-terminal extension of Lsm4 interacts directly with the 3' end of the histone mRNP and is required for efficient histone mRNA degradation.","date":"2013","source":"RNA (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/24255165","citation_count":29,"is_preprint":false},{"pmid":"34515495","id":"PMC_34515495","title":"AtMC1 Associates With LSM4 to Regulate Plant Immunity Through Modulating Pre-mRNA Splicing.","date":"2021","source":"Molecular plant-microbe interactions : MPMI","url":"https://pubmed.ncbi.nlm.nih.gov/34515495","citation_count":20,"is_preprint":false},{"pmid":"11561292","id":"PMC_11561292","title":"Isolation and study of KlLSM4, a Kluyveromyces lactis gene homologous to the essential gene LSM4 of Saccharomyces cerevisiae.","date":"2001","source":"Yeast (Chichester, England)","url":"https://pubmed.ncbi.nlm.nih.gov/11561292","citation_count":20,"is_preprint":false},{"pmid":"16169287","id":"PMC_16169287","title":"HIR1, the co-repressor of histone gene transcription of Saccharomyces cerevisiae, acts as a multicopy suppressor of the apoptotic phenotypes of the LSM4 mRNA degradation mutant.","date":"2005","source":"FEMS yeast research","url":"https://pubmed.ncbi.nlm.nih.gov/16169287","citation_count":18,"is_preprint":false},{"pmid":"19088440","id":"PMC_19088440","title":"LSm4 associates with the plasma membrane and acts as a co-factor in cell volume regulation.","date":"2008","source":"Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/19088440","citation_count":15,"is_preprint":false},{"pmid":"22615807","id":"PMC_22615807","title":"Crystal structures of Lsm3, Lsm4 and Lsm5/6/7 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biologiia","url":"https://pubmed.ncbi.nlm.nih.gov/36976747","citation_count":0,"is_preprint":false},{"pmid":"42093213","id":"PMC_42093213","title":"The Rice Stripe Virus p2 Interacts With Lsm1 and Disrupts the Lsm1-Lsm4 Complex to Facilitate the Viral infection.","date":"2026","source":"Molecular plant pathology","url":"https://pubmed.ncbi.nlm.nih.gov/42093213","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":11732,"output_tokens":3442,"usd":0.043413,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":11024,"output_tokens":3951,"usd":0.076948,"stage2_stop_reason":"end_turn"},"total_usd":0.120361,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2001,\n      \"finding\": \"Human LSM4 contains symmetrically dimethylated arginine (sDMA) residues in vivo, as determined by mass spectrometry and protein sequencing. This symmetrical dimethylation is required for binding of LSM4 to the Tudor domain of the SMN protein; inhibition of dimethylation by S-adenosylhomocysteine abolished LSM4-SMN Tudor interaction. The PRMT responsible is cytoplasmic.\",\n      \"method\": \"Mass spectrometry, protein sequencing, in vitro methylation assay with HeLa cytosolic and nuclear extracts, synthetic peptide competition assay\",\n      \"journal\": \"RNA (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mass spectrometry identification of modification, in vitro methylation reconstitution, peptide inhibition experiments, multiple orthogonal methods in one rigorous study\",\n      \"pmids\": [\"11720283\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The C-terminal RGG domain of human LSM4 promotes Processing Body (PB) accumulation in human cells. Symmetric dimethylation of arginines within the RGG domain by PRMT5 stimulates PB formation. An RGG-deleted LSM4 mutant failed to rescue PB formation in cells depleted of endogenous LSM4, although it retained the ability to assemble into the Lsm1-7 complex, associate with decapping factors, and promote mRNA decay and translational repression. The HAT1-RBBP7 acetyltransferase complex was identified as an interaction partner of the Lsm4 RGG domain, but no role for this complex in PB metabolism was found.\",\n      \"method\": \"RNAi depletion of endogenous LSM4 with re-expression of deletion mutants, PRMT5 depletion, Co-immunoprecipitation, mRNA decay and translational repression assays, fluorescence microscopy of PBs\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal functional rescue, multiple deletion mutants, depletion of writer enzyme (PRMT5), several orthogonal readouts in a single thorough study\",\n      \"pmids\": [\"27247266\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"The C-terminal extension of Lsm4 (beyond the Sm domain) directly interacts with both SLBP and 3'hExo on the histone mRNP. Mutations in the C-terminal tail of Lsm4 that prevent SLBP and 3'hExo binding reduce the rate of histone mRNA degradation when DNA synthesis is inhibited.\",\n      \"method\": \"Direct binding assays (pulldown/co-immunoprecipitation), site-directed mutagenesis of C-terminal tail, histone mRNA decay assays in mammalian cells\",\n      \"journal\": \"RNA (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — direct binding assay, mutagenesis with functional decay readout, two orthogonal methods in single study\",\n      \"pmids\": [\"24255165\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Crystal structures of S. pombe Lsm4 (and Lsm3, Lsm5/6/7) were solved, revealing a conserved Sm fold. In the crystal lattice Lsm4 forms a trimer; analytical ultracentrifugation showed Lsm4 undergoes a dynamic equilibrium between monomer and trimer in solution. No RNA binding was detected for Lsm4 alone in RNA binding assays with oligo(U).\",\n      \"method\": \"X-ray crystallography, analytical ultracentrifugation, RNA binding assays\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure determination plus solution AUC and direct RNA binding assay, single study with orthogonal structural and biochemical methods\",\n      \"pmids\": [\"22615807\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"ICln (a multifunctional protein involved in cell volume regulation and RNA splicing) interacts with LSM4 via its PH domain-like fold, suggesting the ICln PH domain serves as a protein-protein interaction platform linking membrane physiology and RNA processing.\",\n      \"method\": \"Protein interaction assay (pulldown/binding assay) with truncated ICln159 mutant and LSM4; structural determination of ICln159 by NMR/crystallography\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — interaction demonstrated but by single pulldown/binding assay; structural context adds support but LSM4-specific mechanism minimally characterized\",\n      \"pmids\": [\"15905169\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"In isotonic conditions, LSM4 associates with the plasma membrane and with ICln (shown by FRET and biochemistry). Hypotonic cell swelling causes dissociation of LSM4 from both the plasma membrane and from ICln. Overexpression of LSM4 inhibits activation kinetics and current density of the swelling-dependent anion channel IClswell, establishing LSM4 as a co-factor in regulatory volume decrease in NIH3T3 and HEK293 cells.\",\n      \"method\": \"FRET, biochemical fractionation, electrophysiology, overexpression of LSM4\",\n      \"journal\": \"Cellular physiology and biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — FRET plus biochemistry plus electrophysiology, single lab but three orthogonal methods\",\n      \"pmids\": [\"19088440\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Disruption of the mLsm4 gene in mice causes peri-implantation lethality: null blastocysts implant but die shortly thereafter, establishing that Lsm4 is an essential gene in mammals. The early lethality indicates its role in splicing cannot be compensated by other Lsm proteins.\",\n      \"method\": \"Promoter trap gene targeting in murine ES cells, homozygous knockout mouse analysis\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean knockout with defined lethal phenotype, genetic loss-of-function with clear developmental readout\",\n      \"pmids\": [\"10629062\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"In K. lactis and S. cerevisiae, the N-terminal 72 amino acids of KlLsm4p containing the Sm-like domains are sufficient to restore cell viability in cells lacking the wild-type protein, but deletion of the carboxy-terminal region results in loss of viability in stationary phase.\",\n      \"method\": \"Complementation assay in K. lactis and S. cerevisiae lsm4 deletion mutants with truncated KlLsm4 constructs\",\n      \"journal\": \"Yeast (Chichester, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic complementation with defined domain deletions in two yeast species, clear functional readout\",\n      \"pmids\": [\"11561292\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"In S. cerevisiae, combined deletion of EDC3 and the Q/N-rich C-terminal domain of Lsm4 (edc3Δ lsm4ΔC double mutant) reduces mRNA stability and increases dependence on Ccr4-mediated deadenylation and decapping. The decapping enzyme catalytic subunit Dcp2 accumulates in the nucleus in this double mutant.\",\n      \"method\": \"Genetic double mutant analysis in yeast, mRNA stability measurements, epistasis with mRNA decay pathway components, localization of Dcp2\",\n      \"journal\": \"Biology open\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with defined double mutant, multiple mRNA stability readouts and localization, single lab\",\n      \"pmids\": [\"27543059\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Overexpression of the Q/N-rich region of yeast Lsm4 eliminates the prions [PSI+], [URE3], and [RNQ+]. Lsm4 forms an amyloid in vivo, and fluorescence correlation spectroscopy showed that during Lsm4-driven [PSI+] elimination, [PSI+] aggregates increase in size before forming foci in mother cells.\",\n      \"method\": \"Overexpression of Lsm4 and subcloning of Q/N-rich region in S. cerevisiae, fluorescence correlation spectroscopy, amyloid detection in vivo\",\n      \"journal\": \"MicrobiologyOpen\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo amyloid formation, FCS, domain mapping by subcloning, single lab with multiple readouts\",\n      \"pmids\": [\"23512891\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Purified full-length human LSM4 protein undergoes concentration-dependent liquid-liquid phase separation (LLPS) in vitro. The C-terminus of LSM4 contains a low-complexity domain predicted to drive LLPS. High salt concentrations and 1,6-hexanediol block LSM4-induced LLPS, and fusion of LSM4 droplets is observed in vitro.\",\n      \"method\": \"In vitro purification from E. coli, wide-field fluorescence microscopy, 1,6-hexanediol and salt sensitivity assays, bioinformatic disorder prediction\",\n      \"journal\": \"Molekuliarnaia biologiia\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — direct in vitro reconstitution of LLPS, but single lab, no mutagenesis validation, no cellular functional consequence demonstrated\",\n      \"pmids\": [\"36976747\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"tRF-31 (a tRNA-derived small RNA) binds directly to LSM4 under normoxic conditions. Under hypoxia, reduced tRF-31 leads to decreased ubiquitination of LSM4, enhancing its protein stability. Stabilized LSM4 translocates to the nucleus and promotes splicing of EDN1 pre-mRNA, driving proliferation of pulmonary artery endothelial cells.\",\n      \"method\": \"Binding assay (tRF-31–LSM4 interaction), ubiquitination assay, nuclear fractionation, RNA splicing analysis, overexpression and knockdown in PAECs\",\n      \"journal\": \"European journal of pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — multiple methods (binding, ubiquitination, localization, splicing), but single lab and limited mechanistic controls for each step\",\n      \"pmids\": [\"41354297\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SF3B4 physically interacts with LSM4 (shown by Co-IP), and SF3B4 knockdown-mediated inhibition of NSCLC cell functions is rescued by LSM4 overexpression, placing LSM4 downstream of SF3B4 in a pathway promoting lung cancer cell growth, metastasis, and stemness.\",\n      \"method\": \"Co-immunoprecipitation (Co-IP), RIP, MeRIP, cell functional rescue assays, xenograft mouse models\",\n      \"journal\": \"Thoracic cancer\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP for interaction, rescue experiment with LSM4 overexpression is phenotypic only, no defined molecular mechanism for LSM4 activity\",\n      \"pmids\": [\"38462740\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"LSM4 is an essential Sm-like protein that assembles into the cytoplasmic Lsm1-7 complex to promote mRNA decapping and decay; its C-terminal extension (RGG domain in humans, Q/N-rich in yeast) drives Processing Body (P-body) formation through liquid-liquid phase separation stimulated by PRMT5-mediated symmetric arginine dimethylation, while the same C-terminal tail directly contacts SLBP and 3'hExo on histone mRNPs to facilitate histone mRNA degradation; symmetrical dimethylation of LSM4 arginines also mediates binding to the SMN Tudor domain, linking LSM4 to snRNP biogenesis; and under hypoxic conditions LSM4 stability is regulated by ubiquitination, with stabilized LSM4 translocating to the nucleus to influence pre-mRNA splicing.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"LSM4 is an essential Sm-like protein that, beyond its conserved Sm-fold core, uses a C-terminal extension to organize cytoplasmic mRNA decay and Processing Body (PB) assembly [#1, #3]. The Sm domain adopts the canonical Lsm fold and exists in a dynamic monomer–trimer equilibrium, but does not bind oligo(U) RNA on its own, consistent with function within the assembled Lsm1-7 complex rather than as an isolated subunit [#3]. The C-terminal RGG domain is dispensable for Lsm1-7 assembly, decapping-factor association, and bulk mRNA decay yet is required to drive PB accumulation, an activity stimulated by PRMT5-catalyzed symmetric arginine dimethylation of the RGG residues [#1]; purified full-length LSM4 phase-separates in vitro through its low-complexity C-terminus, providing a biophysical basis for this PB-scaffolding role [#10]. Symmetric dimethylation of LSM4 arginines also creates the binding determinant for the SMN Tudor domain, linking LSM4 to snRNP biogenesis machinery [#0]. The same C-terminal tail directly contacts SLBP and 3'hExo on histone mRNPs and is required for efficient histone mRNA degradation when DNA synthesis is blocked [#2]. Genetically, LSM4 is essential in mammals: null mouse blastocysts implant but die peri-implantation, a lethality the early embryo cannot compensate with other Lsm proteins [#6], and in yeast the Sm-like core suffices for viability while the Q/N-rich C-terminal region is needed for stationary-phase survival and contributes to mRNA stability together with EDC3 [#7, #8]. LSM4 stability is further controlled by ubiquitination: under hypoxia, loss of the tRNA-derived fragment tRF-31 reduces LSM4 ubiquitination, stabilizing the protein and promoting its nuclear translocation to drive EDN1 pre-mRNA splicing [#11].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Establishing whether LSM4 is genetically essential in mammals defined its non-redundant importance in early development.\",\n      \"evidence\": \"Promoter-trap gene targeting and homozygous knockout analysis in mice\",\n      \"pmids\": [\"10629062\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not identify which molecular function (splicing vs decay) is the lethal deficit\", \"No conditional or tissue-specific dissection\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Identifying symmetric arginine dimethylation on LSM4 and its requirement for SMN Tudor binding connected LSM4 to the snRNP biogenesis machinery.\",\n      \"evidence\": \"Mass spectrometry, in vitro methylation with HeLa extracts, and peptide competition assays\",\n      \"pmids\": [\"11720283\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The specific cytoplasmic PRMT was not identified at this stage\", \"Functional consequence of SMN binding for LSM4 not measured\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Domain dissection in yeast separated the essential Sm-like core from the C-terminal region required only under stationary-phase stress.\",\n      \"evidence\": \"Complementation of lsm4 deletion mutants in K. lactis and S. cerevisiae with truncated constructs\",\n      \"pmids\": [\"11561292\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular reason for stationary-phase requirement not defined\", \"Yeast result may not map directly onto mammalian RGG functions\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Identifying ICln as an LSM4 partner via its PH-like fold hinted at a link between LSM4 and membrane/volume physiology.\",\n      \"evidence\": \"Pulldown/binding assay with truncated ICln159 plus structural determination\",\n      \"pmids\": [\"15905169\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single binding assay without reciprocal validation\", \"Cellular significance not tested in this study\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Functional electrophysiology placed LSM4 as a co-factor in regulatory volume decrease, extending its role beyond RNA metabolism.\",\n      \"evidence\": \"FRET, biochemical fractionation, and electrophysiology with LSM4 overexpression in NIH3T3/HEK293\",\n      \"pmids\": [\"19088440\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking an mRNA-decay protein to anion channels unresolved\", \"Reliance on overexpression\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Crystal structures and solution analysis defined the LSM4 Sm fold and showed it does not bind RNA alone, framing LSM4 as a complex-dependent subunit.\",\n      \"evidence\": \"X-ray crystallography of S. pombe Lsm4, analytical ultracentrifugation, and oligo(U) binding assays\",\n      \"pmids\": [\"22615807\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No structure of the C-terminal extension\", \"Functional meaning of the monomer–trimer equilibrium unclear\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Mapping direct LSM4 C-terminal contacts to SLBP and 3'hExo explained how LSM4 participates in regulated histone mRNA degradation.\",\n      \"evidence\": \"Direct binding assays and C-terminal mutagenesis with histone mRNA decay readouts in mammalian cells\",\n      \"pmids\": [\"24255165\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether dimethylation modulates these contacts not tested\", \"Structural basis of the SLBP/3'hExo interface unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Demonstrating that the Lsm4 Q/N-rich region forms amyloid and antagonizes prions revealed an intrinsic aggregation propensity of the C-terminal tail.\",\n      \"evidence\": \"Overexpression and subcloning in S. cerevisiae, fluorescence correlation spectroscopy, in vivo amyloid detection\",\n      \"pmids\": [\"23512891\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relationship between amyloid behavior and physiological PB assembly not established\", \"Single-lab, overexpression-based\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Reciprocal rescue with deletion mutants separated PB assembly from decay and pinned PB formation on PRMT5-modified RGG residues.\",\n      \"evidence\": \"RNAi/re-expression of LSM4 mutants, PRMT5 depletion, Co-IP, decay/translational repression assays, and PB microscopy\",\n      \"pmids\": [\"27247266\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional role of the HAT1-RBBP7 interaction unresolved\", \"How PB loss affects mRNA fate not detailed\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Yeast epistasis showed the Q/N-rich C-terminus and EDC3 jointly support mRNA stability and proper decapping-enzyme localization.\",\n      \"evidence\": \"edc3Δ lsm4ΔC double mutant analysis with mRNA stability, decay-pathway epistasis, and Dcp2 localization\",\n      \"pmids\": [\"27543059\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of nuclear Dcp2 accumulation unexplained\", \"Direct vs indirect contribution of Lsm4 C-terminus unclear\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"In vitro reconstitution showed full-length LSM4 undergoes concentration-dependent LLPS, providing a biophysical basis for its PB-scaffolding activity.\",\n      \"evidence\": \"Purified LSM4 with fluorescence microscopy, hexanediol/salt sensitivity, and disorder prediction\",\n      \"pmids\": [\"36976747\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No mutagenesis linking LLPS to specific residues\", \"No cellular functional consequence demonstrated\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"An SF3B4–LSM4 interaction was placed in a lung-cancer growth pathway with LSM4 acting downstream of SF3B4.\",\n      \"evidence\": \"Co-IP, RIP/MeRIP, rescue assays, and xenograft models in NSCLC\",\n      \"pmids\": [\"38462740\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single Co-IP without reciprocal validation\", \"Rescue is phenotypic with no defined molecular activity for LSM4\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Linking tRF-31 binding to LSM4 ubiquitination and nuclear translocation revealed a hypoxia-responsive control of LSM4 stability and splicing output.\",\n      \"evidence\": \"Binding and ubiquitination assays, nuclear fractionation, and EDN1 splicing analysis in pulmonary artery endothelial cells\",\n      \"pmids\": [\"41354297\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The ubiquitin ligase responsible is not identified\", \"How tRF-31 binding mechanistically promotes ubiquitination unclear\", \"Single-lab with limited per-step controls\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How LSM4's cytoplasmic decay/PB roles, its modification-dependent SMN/snRNP links, and its hypoxia-induced nuclear splicing function are integrated into a single regulatory logic remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model coupling LSM4 dimethylation, ubiquitination, and subcellular partitioning\", \"Structural basis of the C-terminal extension and its partner interfaces undetermined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [3, 11]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1, 10]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [11]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0008953854\", \"supporting_discovery_ids\": [1, 2]}\n    ],\n    \"complexes\": [\n      \"Lsm1-7 complex\"\n    ],\n    \"partners\": [\n      \"SMN\",\n      \"PRMT5\",\n      \"SLBP\",\n      \"3'hExo\",\n      \"ICln\",\n      \"SF3B4\",\n      \"EDC3\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}