{"gene":"NIP7","run_date":"2026-04-29T11:37:56","timeline":{"discoveries":[{"year":2007,"finding":"The C-terminal PUA domain of Nip7 mediates specific RNA binding, with preference for polyuridine sequences. Crystal structure of archaeal Pyrococcus abyssi Nip7 revealed a two-domain architecture: an N-terminal alpha-beta domain and a C-terminal PUA domain. Structural alignment and site-directed mutagenesis identified key residues in the PUA domain required for RNA interaction (R151, R152, K155, K158 in archaeal protein; corresponding hydrophobic residues in eukaryotic orthologs). Both archaeal and yeast Nip7 orthologs bind polyuridine specifically, and this preference is conserved.","method":"X-ray crystallography, site-directed mutagenesis, RNA interaction assays (EMSA/filter binding), structural alignment","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 — crystal structure combined with mutagenesis and direct RNA binding assays, multiple orthogonal methods in single study","pmids":["18001138"],"is_preprint":false},{"year":2004,"finding":"The crystal structure of KD93 (human NIP7 homologue encoded by HSPC031/UPF0113 family) was solved at 1.9 Å resolution by MAD, revealing two interlinked alpha/beta domains. The C-terminal domain matches the PUA domain of RNA modification enzymes (notably ArcTGT), suggesting a role in RNA binding. The N-terminal domain is structurally unique with no known homologs.","method":"X-ray crystallography (MAD phasing at 1.9 Å), structural homology analysis (DALI)","journal":"Journal of structural biology","confidence":"Medium","confidence_rationale":"Tier 1 structure, but functional validation of RNA binding not performed in this study; structural inference only","pmids":["15522784"],"is_preprint":false},{"year":2010,"finding":"Human NIP7 is required for accurate pre-rRNA processing and 18S rRNA maturation. Conditional knockdown of NIP7 in HEK293 cells caused decreased 34S pre-rRNA and accumulation of 26S and 21S pre-rRNA intermediates, indicating slower processing at site 2. NIP7 depletion also caused an imbalance in the 40S/60S subunit ratio and inhibited cell proliferation. NIP7 protein localizes exclusively to the nuclear compartment and co-sediments with 40S–80S complexes, consistent with association with nucleolar pre-ribosomal particles.","method":"Conditional siRNA knockdown, Northern blotting (pre-rRNA analysis), sucrose gradient sedimentation, subcellular fractionation, cell proliferation assay","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (knockdown, Northern blot, fractionation) with specific molecular and cellular phenotypes","pmids":["20798176"],"is_preprint":false},{"year":2011,"finding":"Human NIP7 physically interacts with FTSJ3 (putative ortholog of yeast Spb1p methyltransferase) in human cells, as demonstrated by yeast two-hybrid, co-localization, and co-immunoprecipitation. Conditional knockdown of FTSJ3 causes pre-rRNA processing defects including accumulation of 34S pre-rRNA (spanning A' to site 2b), indicating slower processing at sites A0, 1, and 2, phenocopying NIP7 depletion. Both NIP7 and FTSJ3 are thus functionally linked in the pathway leading to 18S rRNA maturation.","method":"Yeast two-hybrid, co-immunoprecipitation, co-localization (immunofluorescence), conditional siRNA knockdown, Northern blotting","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 — reciprocal interaction confirmed by multiple methods (Y2H, co-IP, colocalization) plus functional epistasis via parallel knockdowns","pmids":["22195017"],"is_preprint":false},{"year":2024,"finding":"Chlamydomonas reinhardtii NIP7 (CrNip7) functionally complements yeast NIP7 deletion, implicating it in 60S ribosomal subunit biogenesis. Protein interaction studies via yeast two-hybrid identified two potential CrNip7 partners: UNC-p and G-patch domain protein. Nucleic acid interaction assays showed that both the N- and C-terminal domains of CrNip7 participate in rRNA binding.","method":"Yeast complementation assay, paromomycin resistance test, yeast two-hybrid, nucleic acid interaction assay, in silico structural analysis","journal":"Biochimica et biophysica acta. Proteins and proteomics","confidence":"Medium","confidence_rationale":"Tier 2 complementation and Y2H, but interactions not yet confirmed by co-IP and partners are novel/unvalidated","pmids":["39216654"],"is_preprint":false},{"year":2025,"finding":"NIP7 promotes tumor growth in anaplastic thyroid cancer by upregulating UBE2C (ubiquitin-conjugating enzyme E2C) at the translational level. NIP7 silencing reduced UBE2C protein but not mRNA levels; the SUnSET assay combined with co-immunoprecipitation indicated NIP7 affects UBE2C translation. UBE2C overexpression rescued the proliferation defect caused by NIP7 knockdown. Both NIP7 and UBE2C regulate DNA replication pathway genes (POLE2, RFC4). NIP7 protein localizes predominantly to the nucleus in ATC cells.","method":"siRNA knockdown, CCK-8 proliferation assay, colony formation assay, xenograft tumor model, SUnSET translation assay, co-immunoprecipitation, qRT-PCR, Western blotting, GSEA","journal":"Zhejiang da xue xue bao. Yi xue ban","confidence":"Medium","confidence_rationale":"Tier 2 — multiple methods including translation assay and rescue experiment, but single lab and mechanistic link between NIP7 ribosome function and UBE2C translation not fully resolved","pmids":["40461291"],"is_preprint":false}],"current_model":"NIP7 is a conserved nucleolar trans-acting factor with a two-domain architecture (N-terminal alpha-beta domain and C-terminal PUA domain) that binds polyuridine RNA via its PUA domain; in human cells it localizes to the nucleus, associates with pre-ribosomal particles, and is required for accurate pre-rRNA processing at site 2 to produce 18S rRNA, functioning in physical and functional complex with the methyltransferase FTSJ3, and additionally promotes translation of UBE2C to support cell proliferation in cancer contexts."},"narrative":{"teleology":[{"year":2004,"claim":"Determining the three-dimensional structure of human NIP7 revealed a two-domain fold with a C-terminal PUA domain, establishing the first structural framework for predicting an RNA-binding function.","evidence":"X-ray crystallography at 1.9 Å resolution (MAD phasing) of recombinant human NIP7 (KD93/HSPC031), with DALI structural comparison to known PUA domains","pmids":["15522784"],"confidence":"Medium","gaps":["RNA binding was inferred from structural homology but not experimentally tested in this study","No functional assays linking the structure to ribosome biogenesis were performed"]},{"year":2007,"claim":"Direct RNA-binding activity was demonstrated and mapped to the PUA domain, resolving which domain mediates substrate recognition and establishing polyuridine as a preferred ligand.","evidence":"Crystal structure of archaeal Nip7 (P. abyssi), site-directed mutagenesis of PUA domain residues, EMSA and filter-binding assays with yeast and archaeal orthologs","pmids":["18001138"],"confidence":"High","gaps":["The specific in vivo rRNA targets of NIP7 PUA domain binding were not identified","Functional consequence of RNA-binding mutants on ribosome biogenesis was not tested"]},{"year":2010,"claim":"NIP7 was shown to be required for pre-rRNA processing at site 2, directly linking its function to 18S rRNA maturation and 40S subunit production in human cells.","evidence":"Conditional siRNA knockdown of NIP7 in HEK293 cells, Northern blotting of pre-rRNA intermediates, sucrose gradient sedimentation, subcellular fractionation, and proliferation assays","pmids":["20798176"],"confidence":"High","gaps":["The precise mechanism by which NIP7 facilitates cleavage at site 2 remains undefined","Whether NIP7 acts catalytically or as a structural scaffold on the pre-ribosome is unknown"]},{"year":2011,"claim":"Identification of FTSJ3 as a direct physical and functional partner established NIP7 as part of a biogenesis module, with parallel knockdown phenotypes confirming their cooperation in the same pre-rRNA processing pathway.","evidence":"Yeast two-hybrid, co-immunoprecipitation, co-localization by immunofluorescence, and conditional siRNA knockdown of FTSJ3 with Northern blot analysis in human cells","pmids":["22195017"],"confidence":"High","gaps":["Whether NIP7 modulates FTSJ3 methyltransferase activity or vice versa is not determined","The pre-ribosomal particle on which the NIP7–FTSJ3 complex acts has not been structurally resolved"]},{"year":2024,"claim":"Cross-species complementation in Chlamydomonas confirmed that NIP7's role in 60S subunit biogenesis is functionally conserved across deep evolutionary distances and identified novel candidate interaction partners.","evidence":"Yeast NIP7-deletion complementation by CrNip7, yeast two-hybrid identification of UNC-p and G-patch domain protein partners, nucleic acid interaction assays","pmids":["39216654"],"confidence":"Medium","gaps":["Novel partners (UNC-p, G-patch protein) await co-IP confirmation and functional validation","Whether the dual-domain rRNA binding observed in Chlamydomonas NIP7 reflects the mammalian protein is untested"]},{"year":2025,"claim":"A cancer-specific function was uncovered in which NIP7 promotes translation of the cell-cycle ubiquitin-conjugating enzyme UBE2C, linking ribosome biogenesis factor activity to oncogenic proliferation.","evidence":"siRNA knockdown in anaplastic thyroid cancer cells, SUnSET translation assay, UBE2C rescue experiment, xenograft tumor model, Western blotting","pmids":["40461291"],"confidence":"Medium","gaps":["Whether NIP7 regulates UBE2C translation via general ribosome biogenesis or a specific mRNA-level mechanism is unresolved","Findings from a single lab in one cancer type; generalizability is untested","Direct NIP7–UBE2C mRNA interaction has not been demonstrated"]},{"year":null,"claim":"The precise catalytic or structural mechanism by which NIP7 facilitates pre-rRNA cleavage at site 2, and whether its RNA-binding activity is required in cis on the pre-ribosome, remain open questions.","evidence":"","pmids":[],"confidence":"High","gaps":["No cryo-EM or crosslinking data resolve NIP7's binding site on the human pre-ribosomal particle","Separation-of-function mutants distinguishing RNA binding from protein–protein interaction roles are lacking","Structural basis for NIP7–FTSJ3 complex formation is unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[0,1,4]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[2,5]},{"term_id":"GO:0005730","term_label":"nucleolus","supporting_discovery_ids":[2,3]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[2,3,4]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[2,4]}],"complexes":[],"partners":["FTSJ3"],"other_free_text":[]},"mechanistic_narrative":"NIP7 is a conserved nucleolar trans-acting factor required for ribosome biogenesis, functioning in pre-rRNA processing and ribosomal subunit maturation. Its two-domain architecture—an N-terminal alpha-beta domain and a C-terminal PUA domain—mediates specific RNA binding with preference for polyuridine sequences, as demonstrated by crystallography and mutagenesis of the archaeal ortholog and confirmed for the eukaryotic protein [PMID:18001138, PMID:15522784]. In human cells, NIP7 localizes to the nucleus, co-sediments with pre-ribosomal particles, and is required for accurate processing at site 2 in the pre-rRNA maturation pathway leading to 18S rRNA production; it physically and functionally cooperates with the methyltransferase FTSJ3 in this process [PMID:20798176, PMID:22195017]. NIP7 additionally promotes translation of the cell-cycle regulator UBE2C, linking ribosome biogenesis to cell proliferation in cancer contexts [PMID:40461291]."},"prefetch_data":{"uniprot":{"accession":"Q9Y221","full_name":"60S ribosome subunit biogenesis protein NIP7 homolog","aliases":["KD93","Nucleolar pre-rRNA processing protein NIP7"],"length_aa":180,"mass_kda":20.5,"function":"Required for proper 34S pre-rRNA processing and 60S ribosome subunit assembly","subcellular_location":"Nucleus, nucleolus","url":"https://www.uniprot.org/uniprotkb/Q9Y221/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/NIP7","classification":"Common Essential","n_dependent_lines":1208,"n_total_lines":1208,"dependency_fraction":1.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"NOP2","stoichiometry":4.0},{"gene":"DNAJC8","stoichiometry":0.2},{"gene":"RPS16","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/NIP7","total_profiled":1310},"omim":[{"mim_id":"619204","title":"NUCLEOLAR PRE-rRNA-PROCESSING PROTEIN NIP7; NIP7","url":"https://www.omim.org/entry/619204"},{"mim_id":"618411","title":"FTSJ RNA 2-PRIME-O-METHYLTRANSFERASE 3; FTSJ3","url":"https://www.omim.org/entry/618411"},{"mim_id":"611534","title":"NUCLEOLAR PROTEIN 8; NOL8","url":"https://www.omim.org/entry/611534"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoli","reliability":"Supported"},{"location":"Nucleoplasm","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/NIP7"},"hgnc":{"alias_symbol":["CGI-37","FLJ10296","HSPC031","KD93"],"prev_symbol":[]},"alphafold":{"accession":"Q9Y221","domains":[{"cath_id":"3.10.450.220","chopping":"1-87","consensus_level":"high","plddt":92.312,"start":1,"end":87},{"cath_id":"2.30.130.10","chopping":"95-174","consensus_level":"high","plddt":96.93,"start":95,"end":174}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y221","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y221-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y221-F1-predicted_aligned_error_v6.png","plddt_mean":93.94},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=NIP7","jax_strain_url":"https://www.jax.org/strain/search?query=NIP7"},"sequence":{"accession":"Q9Y221","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9Y221.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9Y221/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y221"}},"corpus_meta":[{"pmid":"21710975","id":"PMC_21710975","title":"Arabidopsis thaliana NIP7;1: an anther-specific boric acid transporter of the aquaporin superfamily regulated by an unusual tyrosine in helix 2 of the transport pore.","date":"2011","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21710975","citation_count":54,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"22195017","id":"PMC_22195017","title":"The human nucleolar protein FTSJ3 associates with NIP7 and functions in pre-rRNA processing.","date":"2011","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22195017","citation_count":32,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"20798176","id":"PMC_20798176","title":"The NIP7 protein is required for accurate pre-rRNA processing in human cells.","date":"2010","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/20798176","citation_count":30,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"18001138","id":"PMC_18001138","title":"Structural insights into the interaction of the Nip7 PUA domain with polyuridine RNA.","date":"2007","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/18001138","citation_count":12,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"15522784","id":"PMC_15522784","title":"Crystal structure of KD93, a novel protein expressed in human hematopoietic stem/progenitor cells.","date":"2004","source":"Journal of structural biology","url":"https://pubmed.ncbi.nlm.nih.gov/15522784","citation_count":7,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"25315147","id":"PMC_25315147","title":"Molecular dynamics simulations of the Nip7 proteins from the marine deep- and shallow-water Pyrococcus species.","date":"2014","source":"BMC structural biology","url":"https://pubmed.ncbi.nlm.nih.gov/25315147","citation_count":4,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"27924686","id":"PMC_27924686","title":"High temperature and pressure influence the interdomain orientation of Nip7 proteins from P. abyssi and P. furiosus: MD simulations.","date":"2017","source":"Journal of biomolecular structure & dynamics","url":"https://pubmed.ncbi.nlm.nih.gov/27924686","citation_count":3,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"27832721","id":"PMC_27832721","title":"Identification of residues of the archaeal RNA-binding Nip7 proteins specific to environmental conditions.","date":"2016","source":"Journal of bioinformatics and computational biology","url":"https://pubmed.ncbi.nlm.nih.gov/27832721","citation_count":3,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"40461291","id":"PMC_40461291","title":"[NIP7 upregulates the expression of ubiquitin-conjugating enzyme E2 C to promote tumor growth in anaplastic thyroid cancer].","date":"2025","source":"Zhejiang da xue xue bao. Yi xue ban = Journal of Zhejiang University. Medical sciences","url":"https://pubmed.ncbi.nlm.nih.gov/40461291","citation_count":0,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"39216654","id":"PMC_39216654","title":"Assigning roles in Chlamydomonas ribosome biogenesis: The conserved factor NIP7.","date":"2024","source":"Biochimica et biophysica acta. Proteins and proteomics","url":"https://pubmed.ncbi.nlm.nih.gov/39216654","citation_count":0,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"16189514","id":"PMC_16189514","title":"Towards a proteome-scale map of the human protein-protein interaction network.","date":"2005","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/16189514","citation_count":2090,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"22658674","id":"PMC_22658674","title":"Insights into RNA biology from an atlas of mammalian mRNA-binding proteins.","date":"2012","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/22658674","citation_count":1718,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"12477932","id":"PMC_12477932","title":"Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences.","date":"2002","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/12477932","citation_count":1479,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"26186194","id":"PMC_26186194","title":"The BioPlex Network: A Systematic Exploration of the Human Interactome.","date":"2015","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/26186194","citation_count":1118,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"28514442","id":"PMC_28514442","title":"Architecture of the human interactome defines protein communities and disease networks.","date":"2017","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/28514442","citation_count":1085,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"26496610","id":"PMC_26496610","title":"A human interactome in three quantitative dimensions organized by stoichiometries and abundances.","date":"2015","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/26496610","citation_count":1015,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"25416956","id":"PMC_25416956","title":"A proteome-scale map of the human interactome network.","date":"2014","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/25416956","citation_count":977,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"22681889","id":"PMC_22681889","title":"The mRNA-bound proteome and its global occupancy profile on protein-coding transcripts.","date":"2012","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/22681889","citation_count":973,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"15635413","id":"PMC_15635413","title":"Nucleolar proteome dynamics.","date":"2005","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/15635413","citation_count":934,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"14702039","id":"PMC_14702039","title":"Complete sequencing and characterization of 21,243 full-length human cDNAs.","date":"2003","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/14702039","citation_count":754,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"33961781","id":"PMC_33961781","title":"Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.","date":"2021","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/33961781","citation_count":705,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"21873635","id":"PMC_21873635","title":"Phylogenetic-based propagation of functional annotations within the Gene Ontology consortium.","date":"2011","source":"Briefings in bioinformatics","url":"https://pubmed.ncbi.nlm.nih.gov/21873635","citation_count":656,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"29395067","id":"PMC_29395067","title":"High-Density Proximity Mapping Reveals the Subcellular Organization of mRNA-Associated Granules and Bodies.","date":"2018","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/29395067","citation_count":580,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"15489334","id":"PMC_15489334","title":"The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).","date":"2004","source":"Genome research","url":"https://pubmed.ncbi.nlm.nih.gov/15489334","citation_count":438,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"35271311","id":"PMC_35271311","title":"OpenCell: Endogenous tagging for the cartography of human cellular organization.","date":"2022","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/35271311","citation_count":432,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"26344197","id":"PMC_26344197","title":"Panorama of ancient metazoan macromolecular complexes.","date":"2015","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/26344197","citation_count":407,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"10810093","id":"PMC_10810093","title":"Identification of novel human genes evolutionarily conserved in Caenorhabditis elegans by comparative proteomics.","date":"2000","source":"Genome research","url":"https://pubmed.ncbi.nlm.nih.gov/10810093","citation_count":392,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"12429849","id":"PMC_12429849","title":"Functional proteomic analysis of human nucleolus.","date":"2002","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/12429849","citation_count":391,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"34079125","id":"PMC_34079125","title":"A proximity-dependent biotinylation map of a human cell.","date":"2021","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/34079125","citation_count":339,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"30033366","id":"PMC_30033366","title":"Mapping the Genetic Landscape of Human Cells.","date":"2018","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/30033366","citation_count":225,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"29568061","id":"PMC_29568061","title":"An AP-MS- and BioID-compatible MAC-tag enables comprehensive mapping of protein interactions and subcellular localizations.","date":"2018","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/29568061","citation_count":201,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"32807901","id":"PMC_32807901","title":"UFMylation maintains tumour suppressor p53 stability by antagonizing its ubiquitination.","date":"2020","source":"Nature cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/32807901","citation_count":168,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"30804502","id":"PMC_30804502","title":"H4K20me0 recognition by BRCA1-BARD1 directs homologous recombination to sister chromatids.","date":"2019","source":"Nature cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/30804502","citation_count":162,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"11042152","id":"PMC_11042152","title":"Cloning and functional analysis of cDNAs with open reading frames for 300 previously undefined genes expressed in CD34+ hematopoietic stem/progenitor cells.","date":"2000","source":"Genome research","url":"https://pubmed.ncbi.nlm.nih.gov/11042152","citation_count":161,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"30833792","id":"PMC_30833792","title":"A protein-interaction network of interferon-stimulated genes extends the innate immune system landscape.","date":"2019","source":"Nature immunology","url":"https://pubmed.ncbi.nlm.nih.gov/30833792","citation_count":159,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"18461144","id":"PMC_18461144","title":"Systematic identification of mRNAs recruited to argonaute 2 by specific microRNAs and corresponding changes in transcript abundance.","date":"2008","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/18461144","citation_count":148,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"32877691","id":"PMC_32877691","title":"A High-Density Human Mitochondrial Proximity Interaction Network.","date":"2020","source":"Cell metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/32877691","citation_count":148,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"19322201","id":"PMC_19322201","title":"Ubiquitin-mediated proteolysis of HuR by heat shock.","date":"2009","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/19322201","citation_count":142,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"27926873","id":"PMC_27926873","title":"FOXA1 Directs H3K4 Monomethylation at Enhancers via Recruitment of the Methyltransferase MLL3.","date":"2016","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/27926873","citation_count":137,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"35140242","id":"PMC_35140242","title":"Human transcription factor protein interaction networks.","date":"2022","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/35140242","citation_count":123,"is_preprint":false,"source_track":"gene2pubmed"}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":6536,"output_tokens":1494,"usd":0.021009},"stage2":{"model":"claude-opus-4-6","input_tokens":4732,"output_tokens":1915,"usd":0.107302},"total_usd":0.285838,"stage1_batch_id":"msgbatch_012ZiiCUBfB62NCTQd4Bk1Jo","stage2_batch_id":"msgbatch_01Xuqq9aUHoQouS7UVGZNStZ","note":"batch pricing = 50% of standard","round2_stage1":{"model":"claude-sonnet-4-6","input_tokens":18358,"output_tokens":2410,"usd":0.045612},"round2_rules_fired":"R3","round2_stage2":{"model":"claude-opus-4-6","input_tokens":5367,"output_tokens":1911,"usd":0.111915}},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2010,\n      \"finding\": \"Human NIP7 is required for accurate pre-rRNA processing, specifically at processing site 2, and its knockdown causes a decrease in 34S pre-rRNA and increases in 26S and 21S pre-rRNA concentrations, implicating it in 18S rRNA maturation. NIP7 is restricted to the nuclear compartment and co-sediments with 40S–80S complexes, suggesting association with nucleolar pre-ribosomal particles.\",\n      \"method\": \"Conditional knockdown (siRNA) with pre-rRNA processing analysis, subcellular fractionation, sedimentation assays\",\n      \"journal\": \"Nucleic Acids Research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KD with defined pre-rRNA processing phenotype and localization data, multiple orthogonal methods\",\n      \"pmids\": [\"20798176\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Human NIP7 interacts with FTSJ3 (a putative ortholog of yeast Spb1p), a nucleolar protein involved in pre-rRNA processing; FTSJ3 knockdown causes accumulation of 34S pre-rRNA and affects processing at sites A0, 1, and 2, linking FTSJ3 and NIP7 to the 18S rRNA maturation pathway.\",\n      \"method\": \"Yeast two-hybrid, coimmunoprecipitation, colocalization, conditional knockdown with pre-rRNA processing analysis\",\n      \"journal\": \"PloS One\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP, colocalization, and functional knockdown with defined rRNA processing phenotype\",\n      \"pmids\": [\"22195017\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"The C-terminal PUA domain of Nip7 mediates specific binding to polyuridine RNA; specific residues of the PUA domain identified by site-directed mutagenesis are required for RNA interaction, and this polyuridine-binding preference is conserved between archaeal (Pyrococcus abyssi) and eukaryotic Nip7 orthologues.\",\n      \"method\": \"Crystal structure determination, structural alignment, RNA interaction assays, site-directed mutagenesis\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure plus mutagenesis and in vitro RNA binding assays\",\n      \"pmids\": [\"18001138\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"The crystal structure of KD93 (a human NIP7 homologue encoded by HSPC031) was solved at 1.9 Å resolution, revealing two interlinked alpha/beta domains; structural homology of the C-terminal domain to the PUA domain of RNA modification enzymes (ArcTGT) suggests RNA-binding function.\",\n      \"method\": \"X-ray crystallography (MAD), structure-based homology analysis (DALI)\",\n      \"journal\": \"Journal of Structural Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 structure but only inferred RNA-binding function from homology, no direct functional validation in this paper\",\n      \"pmids\": [\"15522784\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"NIP7 promotes translation of UBE2C protein without affecting UBE2C mRNA levels in anaplastic thyroid cancer cells; NIP7 knockdown reduces UBE2C protein, inhibits cell proliferation and tumor growth, and UBE2C overexpression rescues the proliferation defect caused by NIP7 silencing.\",\n      \"method\": \"siRNA knockdown, SUnSET translation assay, co-immunoprecipitation, CCK-8 proliferation assay, colony formation, xenograft tumor model\",\n      \"journal\": \"Journal of Zhejiang University. Medical sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (SUnSET + Co-IP + rescue experiment) from single lab\",\n      \"pmids\": [\"40461291\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Chlamydomonas reinhardtii NIP7 (CrNip7) can functionally complement yeast NIP7 in 60S ribosomal subunit biogenesis; yeast two-hybrid identified UNC-p and G-patch domain proteins as potential CrNip7 interactors; both N- and C-terminal domains of CrNip7 interact with rRNA.\",\n      \"method\": \"Protein complementation assay in yeast, paromomycin resistance test, yeast two-hybrid, nucleic acid interaction assays, in silico structural modeling\",\n      \"journal\": \"Biochimica et Biophysica Acta. Proteins and Proteomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional complementation and two-hybrid with nucleic acid binding assays, but single lab\",\n      \"pmids\": [\"39216654\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"Human NIP7 is a nucleolar RNA-binding protein whose PUA domain binds polyuridine RNA; it associates with pre-ribosomal particles (40S–80S) and interacts with FTSJ3 to facilitate pre-rRNA processing at sites A0, 1, and 2, thereby enabling 18S rRNA maturation and 40S subunit biogenesis; additionally, NIP7 promotes translational upregulation of UBE2C to support cell proliferation.\"\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\nI'll classify each paper first, then extract discoveries only from KEPT papers.\n\n**Classification:**\n\n- Paper [1] (PMID:21710975): Arabidopsis NIP7;1 aquaporin — EXCLUDE (symbol collision: plant aquaporin, unrelated to human NIP7 ribosome biogenesis protein)\n- Paper [2] (PMID:22195017): Human NIP7 + FTSJ3 in pre-rRNA processing — KEEP\n- Paper [3] (PMID:20798176): Human NIP7 required for pre-rRNA processing — KEEP\n- Paper [4] (PMID:18001138): Nip7 PUA domain structure and RNA binding (archaeal/yeast orthologs) — KEEP (ortholog, consistent function)\n- Paper [5] (PMID:15522784): KD93/NIP7 homologue crystal structure — KEEP (human NIP7 homologue, structural insight)\n- Paper [6] (PMID:25315147): MD simulations of archaeal Nip7 — KEEP (ortholog structural dynamics, borderline but consistent)\n- Paper [7] (PMID:27924686): MD simulations of archaeal Nip7 interdomain — KEEP (ortholog)\n- Paper [8] (PMID:27832721): Archaeal Nip7 sequence analysis — Low mechanistic value, but KEEP as ortholog\n- Paper [9] (PMID:40461291): NIP7 promotes ATC tumor growth via UBE2C — KEEP\n- Paper [10] (PMID:39216654): Chlamydomonas NIP7 in ribosome biogenesis — KEEP (ortholog)\n\n**Additional curated papers:** These are all large-scale interactome/proteome surveys (BioPlex, BioID, etc.) or completely unrelated mechanistic papers (BRCA1, HuR, FOXA1, p53/UFMylation). None specifically characterize NIP7 mechanism — they are high-throughput datasets where NIP7 may appear incidentally. EXCLUDE all for discovery extraction (no specific NIP7 mechanistic findings extractable).\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2007,\n      \"finding\": \"The C-terminal PUA domain of Nip7 mediates specific RNA binding, with preference for polyuridine sequences. Crystal structure of archaeal Pyrococcus abyssi Nip7 revealed a two-domain architecture: an N-terminal alpha-beta domain and a C-terminal PUA domain. Structural alignment and site-directed mutagenesis identified key residues in the PUA domain required for RNA interaction (R151, R152, K155, K158 in archaeal protein; corresponding hydrophobic residues in eukaryotic orthologs). Both archaeal and yeast Nip7 orthologs bind polyuridine specifically, and this preference is conserved.\",\n      \"method\": \"X-ray crystallography, site-directed mutagenesis, RNA interaction assays (EMSA/filter binding), structural alignment\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure combined with mutagenesis and direct RNA binding assays, multiple orthogonal methods in single study\",\n      \"pmids\": [\"18001138\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"The crystal structure of KD93 (human NIP7 homologue encoded by HSPC031/UPF0113 family) was solved at 1.9 Å resolution by MAD, revealing two interlinked alpha/beta domains. The C-terminal domain matches the PUA domain of RNA modification enzymes (notably ArcTGT), suggesting a role in RNA binding. The N-terminal domain is structurally unique with no known homologs.\",\n      \"method\": \"X-ray crystallography (MAD phasing at 1.9 Å), structural homology analysis (DALI)\",\n      \"journal\": \"Journal of structural biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 structure, but functional validation of RNA binding not performed in this study; structural inference only\",\n      \"pmids\": [\"15522784\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Human NIP7 is required for accurate pre-rRNA processing and 18S rRNA maturation. Conditional knockdown of NIP7 in HEK293 cells caused decreased 34S pre-rRNA and accumulation of 26S and 21S pre-rRNA intermediates, indicating slower processing at site 2. NIP7 depletion also caused an imbalance in the 40S/60S subunit ratio and inhibited cell proliferation. NIP7 protein localizes exclusively to the nuclear compartment and co-sediments with 40S–80S complexes, consistent with association with nucleolar pre-ribosomal particles.\",\n      \"method\": \"Conditional siRNA knockdown, Northern blotting (pre-rRNA analysis), sucrose gradient sedimentation, subcellular fractionation, cell proliferation assay\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (knockdown, Northern blot, fractionation) with specific molecular and cellular phenotypes\",\n      \"pmids\": [\"20798176\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Human NIP7 physically interacts with FTSJ3 (putative ortholog of yeast Spb1p methyltransferase) in human cells, as demonstrated by yeast two-hybrid, co-localization, and co-immunoprecipitation. Conditional knockdown of FTSJ3 causes pre-rRNA processing defects including accumulation of 34S pre-rRNA (spanning A' to site 2b), indicating slower processing at sites A0, 1, and 2, phenocopying NIP7 depletion. Both NIP7 and FTSJ3 are thus functionally linked in the pathway leading to 18S rRNA maturation.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, co-localization (immunofluorescence), conditional siRNA knockdown, Northern blotting\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal interaction confirmed by multiple methods (Y2H, co-IP, colocalization) plus functional epistasis via parallel knockdowns\",\n      \"pmids\": [\"22195017\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Chlamydomonas reinhardtii NIP7 (CrNip7) functionally complements yeast NIP7 deletion, implicating it in 60S ribosomal subunit biogenesis. Protein interaction studies via yeast two-hybrid identified two potential CrNip7 partners: UNC-p and G-patch domain protein. Nucleic acid interaction assays showed that both the N- and C-terminal domains of CrNip7 participate in rRNA binding.\",\n      \"method\": \"Yeast complementation assay, paromomycin resistance test, yeast two-hybrid, nucleic acid interaction assay, in silico structural analysis\",\n      \"journal\": \"Biochimica et biophysica acta. Proteins and proteomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 complementation and Y2H, but interactions not yet confirmed by co-IP and partners are novel/unvalidated\",\n      \"pmids\": [\"39216654\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"NIP7 promotes tumor growth in anaplastic thyroid cancer by upregulating UBE2C (ubiquitin-conjugating enzyme E2C) at the translational level. NIP7 silencing reduced UBE2C protein but not mRNA levels; the SUnSET assay combined with co-immunoprecipitation indicated NIP7 affects UBE2C translation. UBE2C overexpression rescued the proliferation defect caused by NIP7 knockdown. Both NIP7 and UBE2C regulate DNA replication pathway genes (POLE2, RFC4). NIP7 protein localizes predominantly to the nucleus in ATC cells.\",\n      \"method\": \"siRNA knockdown, CCK-8 proliferation assay, colony formation assay, xenograft tumor model, SUnSET translation assay, co-immunoprecipitation, qRT-PCR, Western blotting, GSEA\",\n      \"journal\": \"Zhejiang da xue xue bao. Yi xue ban\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple methods including translation assay and rescue experiment, but single lab and mechanistic link between NIP7 ribosome function and UBE2C translation not fully resolved\",\n      \"pmids\": [\"40461291\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"NIP7 is a conserved nucleolar trans-acting factor with a two-domain architecture (N-terminal alpha-beta domain and C-terminal PUA domain) that binds polyuridine RNA via its PUA domain; in human cells it localizes to the nucleus, associates with pre-ribosomal particles, and is required for accurate pre-rRNA processing at site 2 to produce 18S rRNA, functioning in physical and functional complex with the methyltransferase FTSJ3, and additionally promotes translation of UBE2C to support cell proliferation in cancer contexts.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"NIP7 is a nucleolar RNA-binding protein essential for pre-rRNA processing and ribosome biogenesis. Its C-terminal PUA domain binds polyuridine RNA through conserved residues identified by crystallography and mutagenesis, and the protein co-sediments with 40S–80S pre-ribosomal particles in the nucleus [PMID:18001138, PMID:20798176]. NIP7 is required for accurate cleavage at pre-rRNA processing site 2, and it physically interacts with FTSJ3 to coordinate processing at sites A0, 1, and 2, thereby enabling 18S rRNA maturation and 40S subunit production [PMID:20798176, PMID:22195017]. NIP7 also promotes translational upregulation of UBE2C protein in thyroid cancer cells, and NIP7 silencing suppresses cell proliferation in a manner rescued by UBE2C overexpression [PMID:40461291].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"Determining the atomic structure of human NIP7 revealed a two-domain architecture with a C-terminal PUA fold homologous to RNA modification enzymes, establishing it as a candidate RNA-binding protein before any functional data existed.\",\n      \"evidence\": \"X-ray crystallography at 1.9 Å resolution with DALI structural homology analysis\",\n      \"pmids\": [\"15522784\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"RNA-binding function was inferred from structural homology only, not directly tested\",\n        \"No functional assays linking the protein to ribosome biogenesis were performed\"\n      ]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Direct RNA-binding experiments and mutagenesis demonstrated that the PUA domain of NIP7 specifically binds polyuridine RNA through conserved residues, validating the structural prediction and establishing the molecular basis for its RNA interaction.\",\n      \"evidence\": \"Crystal structure of archaeal Nip7, in vitro RNA interaction assays, and site-directed mutagenesis of PUA domain residues (Pyrococcus abyssi and eukaryotic orthologs)\",\n      \"pmids\": [\"18001138\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The in vivo RNA targets in human cells were not identified\",\n        \"How polyuridine binding relates to pre-rRNA substrate recognition was unknown\"\n      ]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Knockdown of NIP7 in human cells revealed its requirement for pre-rRNA processing at site 2 and its association with pre-ribosomal particles, establishing its functional role in 18S rRNA maturation and 40S subunit biogenesis.\",\n      \"evidence\": \"siRNA knockdown with Northern blot analysis of pre-rRNA intermediates, subcellular fractionation, and sucrose gradient sedimentation in human cells\",\n      \"pmids\": [\"20798176\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether NIP7 acts catalytically or as a structural scaffold in processing was not resolved\",\n        \"The identity of the pre-ribosomal complex(es) containing NIP7 was not defined at subunit resolution\"\n      ]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identification of FTSJ3 as a direct NIP7 interaction partner, with FTSJ3 knockdown affecting processing at sites A0, 1, and 2, connected NIP7 to a broader rRNA processing network and defined its partnership within the 18S maturation pathway.\",\n      \"evidence\": \"Yeast two-hybrid, reciprocal co-immunoprecipitation, colocalization, and siRNA knockdown with pre-rRNA processing analysis in human cells\",\n      \"pmids\": [\"22195017\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether NIP7–FTSJ3 form a stable complex on the pre-ribosome or interact transiently was not determined\",\n        \"The enzymatic contribution of FTSJ3 methyltransferase activity to NIP7-dependent processing steps was not tested\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Functional complementation of yeast NIP7 by Chlamydomonas CrNip7 demonstrated evolutionary conservation of NIP7 function in 60S subunit biogenesis and showed that both N- and C-terminal domains interact with rRNA.\",\n      \"evidence\": \"Yeast complementation assay, yeast two-hybrid with novel interactors, nucleic acid interaction assays in Chlamydomonas/yeast system\",\n      \"pmids\": [\"39216654\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single-lab study; interactors identified only by yeast two-hybrid without reciprocal validation\",\n        \"Whether human NIP7 similarly participates in 60S biogenesis (as well as 40S) has not been directly tested\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Discovery that NIP7 promotes UBE2C translation in thyroid cancer cells revealed a non-canonical role for NIP7 in selective translational regulation that drives cell proliferation, extending its function beyond general ribosome biogenesis.\",\n      \"evidence\": \"siRNA knockdown, SUnSET translation assay, co-immunoprecipitation of NIP7–UBE2C mRNP, rescue by UBE2C overexpression, xenograft tumor model in anaplastic thyroid cancer cells\",\n      \"pmids\": [\"40461291\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single-lab finding; selectivity of translational regulation for UBE2C versus other mRNAs not broadly profiled\",\n        \"Mechanism by which NIP7 enhances translation of a specific mRNA is unknown\",\n        \"Whether this translational role depends on NIP7's PUA domain RNA-binding activity was not tested\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the identity of NIP7's direct pre-rRNA binding sites in vivo, the structural basis for its integration into pre-ribosomal particles, and whether its translational regulatory function in cancer reflects a ribosome-biogenesis-dependent or independent mechanism.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No CLIP or eCLIP data mapping NIP7 binding sites on human pre-rRNA\",\n        \"No cryo-EM structure of NIP7-containing pre-ribosomal complexes\",\n        \"Relationship between ribosome biogenesis function and selective translational control is undefined\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [0, 2, 3, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005730\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [0, 1, 2, 5]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 1, 5]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"FTSJ3\"],\n    \"other_free_text\": []\n  }\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"mechanistic_narrative\": \"NIP7 is a conserved nucleolar trans-acting factor required for ribosome biogenesis, functioning in pre-rRNA processing and ribosomal subunit maturation. Its two-domain architecture—an N-terminal alpha-beta domain and a C-terminal PUA domain—mediates specific RNA binding with preference for polyuridine sequences, as demonstrated by crystallography and mutagenesis of the archaeal ortholog and confirmed for the eukaryotic protein [PMID:18001138, PMID:15522784]. In human cells, NIP7 localizes to the nucleus, co-sediments with pre-ribosomal particles, and is required for accurate processing at site 2 in the pre-rRNA maturation pathway leading to 18S rRNA production; it physically and functionally cooperates with the methyltransferase FTSJ3 in this process [PMID:20798176, PMID:22195017]. NIP7 additionally promotes translation of the cell-cycle regulator UBE2C, linking ribosome biogenesis to cell proliferation in cancer contexts [PMID:40461291].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"Determining the three-dimensional structure of human NIP7 revealed a two-domain fold with a C-terminal PUA domain, establishing the first structural framework for predicting an RNA-binding function.\",\n      \"evidence\": \"X-ray crystallography at 1.9 Å resolution (MAD phasing) of recombinant human NIP7 (KD93/HSPC031), with DALI structural comparison to known PUA domains\",\n      \"pmids\": [\"15522784\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"RNA binding was inferred from structural homology but not experimentally tested in this study\",\n        \"No functional assays linking the structure to ribosome biogenesis were performed\"\n      ]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Direct RNA-binding activity was demonstrated and mapped to the PUA domain, resolving which domain mediates substrate recognition and establishing polyuridine as a preferred ligand.\",\n      \"evidence\": \"Crystal structure of archaeal Nip7 (P. abyssi), site-directed mutagenesis of PUA domain residues, EMSA and filter-binding assays with yeast and archaeal orthologs\",\n      \"pmids\": [\"18001138\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The specific in vivo rRNA targets of NIP7 PUA domain binding were not identified\",\n        \"Functional consequence of RNA-binding mutants on ribosome biogenesis was not tested\"\n      ]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"NIP7 was shown to be required for pre-rRNA processing at site 2, directly linking its function to 18S rRNA maturation and 40S subunit production in human cells.\",\n      \"evidence\": \"Conditional siRNA knockdown of NIP7 in HEK293 cells, Northern blotting of pre-rRNA intermediates, sucrose gradient sedimentation, subcellular fractionation, and proliferation assays\",\n      \"pmids\": [\"20798176\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The precise mechanism by which NIP7 facilitates cleavage at site 2 remains undefined\",\n        \"Whether NIP7 acts catalytically or as a structural scaffold on the pre-ribosome is unknown\"\n      ]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identification of FTSJ3 as a direct physical and functional partner established NIP7 as part of a biogenesis module, with parallel knockdown phenotypes confirming their cooperation in the same pre-rRNA processing pathway.\",\n      \"evidence\": \"Yeast two-hybrid, co-immunoprecipitation, co-localization by immunofluorescence, and conditional siRNA knockdown of FTSJ3 with Northern blot analysis in human cells\",\n      \"pmids\": [\"22195017\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether NIP7 modulates FTSJ3 methyltransferase activity or vice versa is not determined\",\n        \"The pre-ribosomal particle on which the NIP7–FTSJ3 complex acts has not been structurally resolved\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Cross-species complementation in Chlamydomonas confirmed that NIP7's role in 60S subunit biogenesis is functionally conserved across deep evolutionary distances and identified novel candidate interaction partners.\",\n      \"evidence\": \"Yeast NIP7-deletion complementation by CrNip7, yeast two-hybrid identification of UNC-p and G-patch domain protein partners, nucleic acid interaction assays\",\n      \"pmids\": [\"39216654\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Novel partners (UNC-p, G-patch protein) await co-IP confirmation and functional validation\",\n        \"Whether the dual-domain rRNA binding observed in Chlamydomonas NIP7 reflects the mammalian protein is untested\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"A cancer-specific function was uncovered in which NIP7 promotes translation of the cell-cycle ubiquitin-conjugating enzyme UBE2C, linking ribosome biogenesis factor activity to oncogenic proliferation.\",\n      \"evidence\": \"siRNA knockdown in anaplastic thyroid cancer cells, SUnSET translation assay, UBE2C rescue experiment, xenograft tumor model, Western blotting\",\n      \"pmids\": [\"40461291\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether NIP7 regulates UBE2C translation via general ribosome biogenesis or a specific mRNA-level mechanism is unresolved\",\n        \"Findings from a single lab in one cancer type; generalizability is untested\",\n        \"Direct NIP7–UBE2C mRNA interaction has not been demonstrated\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The precise catalytic or structural mechanism by which NIP7 facilitates pre-rRNA cleavage at site 2, and whether its RNA-binding activity is required in cis on the pre-ribosome, remain open questions.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No cryo-EM or crosslinking data resolve NIP7's binding site on the human pre-ribosomal particle\",\n        \"Separation-of-function mutants distinguishing RNA binding from protein–protein interaction roles are lacking\",\n        \"Structural basis for NIP7–FTSJ3 complex formation is unknown\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [0, 1, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [2, 5]},\n      {\"term_id\": \"GO:0005730\", \"supporting_discovery_ids\": [2, 3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [2, 3, 4]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [2, 4]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"FTSJ3\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}