{"gene":"SLBP","run_date":"2026-04-28T20:42:07","timeline":{"discoveries":[{"year":2003,"finding":"SLBP is degraded at the end of S phase via phosphorylation of two threonines (T60 and T62 in the TTP sequence and a consensus cyclin binding site at aa 99-104). Mass spectrometry of purified SLBP from late S-phase cells confirmed phosphorylation of these residues, which triggers proteasomal degradation. Mutation of these residues stabilizes SLBP in G2/M. Nuclear extracts from G1 and G2 cells are deficient in histone pre-mRNA processing, which is restored by recombinant SLBP, demonstrating SLBP is the only cell cycle-regulated factor required for histone pre-mRNA processing.","method":"Mass spectrometry of purified SLBP, site-directed mutagenesis, nuclear extract reconstitution assay","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution, MS identification of phosphosites, mutagenesis validation","pmids":["12588979"],"is_preprint":false},{"year":2009,"finding":"SLBP knockdown by RNAi in U2OS cells reveals that SLBP is required for nuclear export of histone mRNA. Reduced SLBP results in nuclear retention of properly processed histone mRNA, accumulation of cells in S phase, and loss of rapid histone mRNA degradation upon DNA replication inhibition, demonstrating a role for SLBP in histone mRNA export.","method":"RNAi knockdown, RNA FISH, cell fractionation, fluorescence microscopy","journal":"RNA (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 2 — clean KD with defined cellular phenotype (nuclear retention), multiple readouts","pmids":["19155325"],"is_preprint":false},{"year":2016,"finding":"Cyclin F (F-box protein, substrate recognition subunit of SCF complex) is identified as the G2 ubiquitin ligase for SLBP. SLBP interacts with cyclin F via an atypical CY motif; mutation of this motif prevents SLBP degradation in G2. Stable SLBP causes increased loading of H2AFX mRNA onto polyribosomes, elevated H2A.X, persistent γH2A.X signaling, and apoptosis upon genotoxic stress in G2.","method":"Co-immunoprecipitation, CY motif mutagenesis, polyribosome profiling, stable SLBP mutant expression","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP, mutagenesis, functional phenotype with multiple orthogonal readouts","pmids":["27773672"],"is_preprint":false},{"year":2016,"finding":"The CUL4 E3 ubiquitin ligase complex CRL4(WDR23) binds and ubiquitylates SLBP in vitro and in vivo. This ubiquitylation activates SLBP function in histone mRNA 3' end processing without affecting SLBP protein levels; loss of CRL4(WDR23) activity results in histone depletion and impaired DNA replication.","method":"In vitro ubiquitylation assay, co-immunoprecipitation, genetic knockdown, histone mRNA processing assay","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 — in vitro ubiquitylation reconstitution plus in vivo validation with defined phenotype","pmids":["27203182"],"is_preprint":false},{"year":2012,"finding":"The prolyl isomerase Pin1 regulates SLBP degradation and histone mRNA stability. Pin1 promotes SLBP polyubiquitination via the Ser20/Ser23 phosphodegron. Pin1 together with PP2A can dephosphorylate phospho-Thr in the conserved TPNK sequence of the SLBP RNA binding domain in vitro, dissociating SLBP from the histone mRNA hairpin. Pin1 knockdown increases histone mRNA stability and accumulates SLBP in the nucleus.","method":"siRNA knockdown, in vitro dephosphorylation assay (Pin1 + PP2A), ubiquitination assay, RNA stability assay","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1–2 — in vitro biochemical reconstitution, siRNA with multiple readouts, moderate evidence","pmids":["22907757"],"is_preprint":false},{"year":2013,"finding":"Crystal structure of zebrafish SLIP1 bound to the translation-activation domain of SLBP determined at 2.5 Å. SLIP1 is a MIF4G-like homodimer that connects SLBP to translation initiation. A SLIP1-binding motif (SBM) was identified in eIF3g and DBP5; pull-down assays and crystal structure of SLIP1-DBP5 SBM confirmed these interactions. SLIP1 homodimerization and SBM-binding residues are conserved in CTIF.","method":"X-ray crystallography, pull-down assays, structure determination at 2.5 Å and 3.25 Å","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 — crystal structures with biochemical validation by pulldown","pmids":["23804756"],"is_preprint":false},{"year":2004,"finding":"SLBP is a component of the histone mRNP on polyribosomes. Anti-SLBP immunoprecipitation co-precipitates histone mRNA from polyribosomes. When DNA replication is inhibited, histone mRNAs are rapidly degraded but SLBP remains constant and relocalizes to the nucleus, remaining active in RNA binding and histone pre-mRNA processing.","method":"Polyribosome fractionation, co-immunoprecipitation of RNA, subcellular fractionation","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 — polyribosome fractionation + RNA co-IP + functional processing assays","pmids":["15358832"],"is_preprint":false},{"year":2012,"finding":"SLBP has two binding sites for the histone mRNA hairpin within its RNA binding domain: a helix-turn-helix motif (Glu129–Val158) recognizing unpaired uridines in the stem-loop, and a second site (Arg180–Pro200) recognizing the second G-C base pair. Threonine phosphorylation at the conserved TPNK sequence increases SLBP affinity for histone mRNA by slowing off-rate; the adjacent proline acts as a hinge regulating the second binding site.","method":"NMR spectroscopy, kinetic binding assays, phosphorylation analysis","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 — NMR structural mapping with kinetic validation and mutagenesis","pmids":["22439849"],"is_preprint":false},{"year":2013,"finding":"Assembly of the SLIP1-SLBP complex on histone mRNA requires sequential binding: phosphorylated SLBP binds the histone mRNA stem-loop first, then SLIP1 associates to form an active ternary complex. Unphosphorylated SLBP and SLIP1 form an inactive 2:2 heterotetramer that cannot bind histone mRNA; phosphorylation at Thr171 promotes dissociation to the active heterodimer. A single-point SLIP1 mutant near the homodimer interface abolished SLBP interaction and reduced histone mRNA in vivo.","method":"Analytical ultracentrifugation, baculovirus phosphorylated SLBP, alanine scanning mutagenesis, RNA EMSA, in vivo histone mRNA quantification","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 — biophysical reconstitution + mutagenesis + in vivo validation","pmids":["23286197"],"is_preprint":false},{"year":2006,"finding":"SLBP binding to the 3'-UTR of histone pre-mRNA H4-12 induces structural rearrangements that open the HDE hairpin, making it accessible for U7 snRNA anchoring. RNA structure probing and EMSA demonstrated that SLBP facilitates U7 snRNP binding to the pre-mRNA.","method":"RNA structure probing (chemical/enzymatic), EMSA","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 — in vitro RNA probing and EMSA, single lab","pmids":["16982637"],"is_preprint":false},{"year":2004,"finding":"The N-terminal domain of Drosophila SLBP is intrinsically disordered with nascent helical structure at physiological conditions. NMR characterization shows four regions with helical propensity but no well-defined tertiary fold in the absence of RNA, consistent with a disordered-to-ordered transition upon RNA binding.","method":"NMR spectroscopy (15N, 13C labeling), circular dichroism","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 — complete NMR characterization of domain structure","pmids":["15260482"],"is_preprint":false},{"year":2004,"finding":"Phosphorylation of C-terminal serines in the SLBP RNA binding and processing domain (RPD) is necessary for histone pre-mRNA processing in Drosophila. Both serine phosphorylation and RNA binding are required for proper folding of the RPD; the electrostatic effect of phosphorylation can be partially mimicked by serine-to-glutamate mutations.","method":"31P NMR, circular dichroism, in vitro processing assay, phosphomimetic mutagenesis","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 — NMR, mutagenesis, and in vitro processing assay","pmids":["15260483"],"is_preprint":false},{"year":2017,"finding":"FEM1A, FEM1B, and FEM1C (VHL-box CUL2-RING E3 ubiquitin ligase substrate recognition subunits) interact with SLBP via distinct degrons in SLBP's N-terminus and mediate SLBP degradation. An SLBP mutant unable to interact with cyclin F plus all three FEM1 proteins is expressed at higher levels and does not oscillate during the cell cycle. FEM1-SLBP ortholog interactions are conserved in C. elegans and D. melanogaster.","method":"Co-immunoprecipitation, mutagenesis (combined degron mutants), C. elegans genetic depletion of FEM1","journal":"Cell cycle (Georgetown, Tex.)","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP, mutagenesis, evolutionary conservation validated in two model organisms","pmids":["28118078"],"is_preprint":false},{"year":2005,"finding":"SLBP is required for efficient DNA replication. RNAi-mediated removal of SLBP increases the number of cells in S phase and causes slow progression through S phase upon release from a double-thymidine block. Re-expression of an RNAi-resistant SLBP restores proper S-phase progression, demonstrating the effect is specifically due to SLBP loss.","method":"RNAi, rescue with RNAi-resistant SLBP, double-thymidine block cell cycle analysis","journal":"Biochemical Society transactions","confidence":"Medium","confidence_rationale":"Tier 2 — RNAi with genetic rescue, single lab","pmids":["15916543"],"is_preprint":false},{"year":2012,"finding":"Haploinsufficiency of SLBP in Wolf-Hirschhorn syndrome patient-derived cells causes delayed S-to-M phase progression, reduced DNA replication, altered chromatin assembly (reduced histone-chromatin association, elevated soluble chaperone-bound histone H3, increased MNase sensitivity), and increased camptothecin sensitivity.","method":"Patient-derived cell lines with variable 4p deletions, flow cytometry, MNase sensitivity assay, histone-chromatin fractionation","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 — human genetic model with multiple cellular phenotypes, correlative but mechanistically informative","pmids":["22328085"],"is_preprint":false},{"year":2022,"finding":"53BP1 acts as a molecular scaffold for NDPK-mediated phosphorylation of ATP-citrate lyase (ACLY), enhancing ACLY activity, global histone acetylation, and transcriptome-wide gene expression changes. SLBP expression is dependent on 53BP1-ACLY-controlled acetylation at the SLBP promoter, placing SLBP downstream in a 53BP1-ACLY-SLBP axis that coordinates replication-dependent histone biogenesis.","method":"Co-immunoprecipitation, ChIP, ACLY activity assay, transcriptomic analysis","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP, ChIP, functional assays; single lab with multiple methods","pmids":["35037047"],"is_preprint":false},{"year":2014,"finding":"31P NMR demonstrates that a phosphothreonine in the RNA binding domain of SLBP exhibits torsional strain and participates in a hydrogen-bonding network; phosphorylation at this residue promotes assembly of the SLBP-RNA complex through phosphate-coupled folding of an intrinsically disordered region.","method":"31P NMR spectroscopy","journal":"FEBS open bio","confidence":"Medium","confidence_rationale":"Tier 1 method (NMR) but single lab, single technique","pmids":["25379382"],"is_preprint":false},{"year":2019,"finding":"Loss of Slbp function in zebrafish (eisspalte mutants) causes failure of cells to transition from proliferation to differentiation, retinal coloboma, midline axon guidance deficits, and altered expression of neuronal differentiation and axon guidance genes. Cells throughout the CNS remain in the cell cycle at stages when post-mitotic differentiation normally occurs.","method":"Forward genetic screen, genetic mapping, RNAseq, in situ hybridization","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — zebrafish ortholog loss-of-function with defined cellular phenotypes; ortholog confirmed by domain/function conservation","pmids":["30695021"],"is_preprint":false},{"year":2021,"finding":"In Drosophila stage 10B oocytes, a region of SLBP outside the mRNA-processing domain (overlapping a putative nuclear localization sequence) is essential for histone mRNA deposition into the oocyte and for histone gene transcription. A 10-amino-acid deletion or NLS mutations prevent histone gene transcription in stage 10B without affecting S-phase processing function.","method":"SLBP deletion mutant analysis, in situ hybridization, genetic rescue in Drosophila","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 — defined domain mapping by mutagenesis in vivo in Drosophila ortholog","pmids":["33408246"],"is_preprint":false},{"year":2004,"finding":"Yeast three-hybrid system analysis of human SLBP identified critical residues in the RNA binding domain required for histone hairpin recognition. Both the core RBD and flanking N- and C-terminal domains contribute to RNA discrimination.","method":"Yeast three-hybrid system, negative and positive selection screens","journal":"FEBS letters","confidence":"Low","confidence_rationale":"Tier 3 — yeast three-hybrid, single lab, no structural validation","pmids":["14706861"],"is_preprint":false},{"year":2017,"finding":"Nickel and cadmium compounds deplete SLBP mRNA and protein levels, resulting in increased polyadenylated canonical histone H3.1 mRNA. SLBP protein depletion is reversed by proteasome inhibition. Rescue of SLBP mRNA and protein by epigenetic modifiers suggests nickel acts through epigenetic mechanisms to reduce SLBP expression.","method":"Western blot, qRT-PCR, proteasome inhibitor treatment, epigenetic modifier rescue","journal":"PloS one","confidence":"Low","confidence_rationale":"Tier 3 — single lab, indirect mechanistic inference, no direct biochemical reconstitution","pmids":["28306745"],"is_preprint":false},{"year":2025,"finding":"In Drosophila, maternal histone mRNAs are uniquely polyadenylated and have a truncated 3' stem-loop. This noncanonical 3'-end processing requires SLBP but not U7 snRNP during oogenesis. Maternal histone transcripts undergo cytoplasmic poly(A) elongation by Wisp for stabilization and translation, and their translation is activated upon loss of embryonic linker histone dBigH1.","method":"Genetic mutant analysis (SLBP and U7 snRNP mutants in Drosophila), RNA sequencing, polysome analysis, in situ hybridization","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 — Drosophila ortholog genetics with multiple molecular readouts; single study","pmids":["40239992"],"is_preprint":false}],"current_model":"SLBP (stem-loop binding protein) is an intrinsically disordered protein that binds the conserved 3' stem-loop of replication-dependent histone mRNAs, where phosphorylation of a threonine in the TPNK motif of its RNA-binding domain promotes high-affinity RNA binding and correct domain folding; SLBP is the sole cell cycle-regulated factor required for histone pre-mRNA 3'-end processing, participates in nuclear export, translation (via SLIP1/eIF3 interaction), and mRNA degradation of histone mRNAs, and its own abundance is cell-cycle-regulated through sequential ubiquitin-mediated degradation executed by CRL4(WDR23) (activating ubiquitylation), SCF-cyclin F (G2 degradation via a CY motif), and FEM1 family CUL2 ligases (other cell cycle phases), with Pin1/PP2A additionally coordinating SLBP dissociation from histone mRNA and SLBP ubiquitination at the end of S phase."},"narrative":{"teleology":[{"year":2003,"claim":"Establishing that SLBP is the sole cell-cycle-regulated processing factor answered how histone pre-mRNA 3'-end cleavage is restricted to S phase: phosphorylation of T60/T62 triggers proteasomal degradation at the S/G2 boundary, and recombinant SLBP restores processing activity to G1 or G2 nuclear extracts that otherwise lack it.","evidence":"Mass spectrometry of purified SLBP, phosphosite mutagenesis, nuclear extract reconstitution in human cells","pmids":["12588979"],"confidence":"High","gaps":["Identity of the E3 ligase recognizing the T60/T62 phosphodegron was unknown","Whether additional post-translational modifications govern SLBP stability remained open"]},{"year":2004,"claim":"Structural characterization of the RNA-binding domain resolved how an intrinsically disordered protein achieves specific RNA recognition: NMR showed the N-terminal/RBD regions are disordered in isolation but adopt nascent helical structure, and phosphorylation of C-terminal serines in the RPD is required for proper domain folding and processing activity.","evidence":"NMR spectroscopy (Drosophila SLBP), 31P NMR, circular dichroism, in vitro processing assays, phosphomimetic mutagenesis","pmids":["15260482","15260483"],"confidence":"High","gaps":["High-resolution structure of the SLBP–RNA complex was not yet available","Whether phosphorylation-coupled folding operates identically in human SLBP was untested"]},{"year":2004,"claim":"Demonstrating that SLBP remains on histone mRNA on polyribosomes established its post-processing cytoplasmic role: SLBP co-immunoprecipitates with histone mRNA from polyribosome fractions and relocalizes to the nucleus upon replication inhibition while remaining functional for RNA binding.","evidence":"Polyribosome fractionation and RNA co-immunoprecipitation in mammalian cells","pmids":["15358832"],"confidence":"High","gaps":["The mechanism by which SLBP stimulates translation was unclear","How SLBP relocalizes to the nucleus upon replication stress was undefined"]},{"year":2005,"claim":"Linking SLBP to DNA replication efficiency showed that its role extends beyond RNA metabolism: RNAi depletion of SLBP slows S-phase progression, rescued by RNAi-resistant SLBP re-expression.","evidence":"RNAi knockdown with genetic rescue, double-thymidine block, flow cytometry in human cells","pmids":["15916543"],"confidence":"Medium","gaps":["Whether the replication defect is due to histone shortage versus other SLBP functions was not distinguished","Single lab study"]},{"year":2006,"claim":"RNA structure probing revealed that SLBP binding remodels the histone pre-mRNA substrate to expose the histone downstream element for U7 snRNP, explaining how SLBP catalytically facilitates the processing reaction beyond simple stem-loop recognition.","evidence":"Chemical/enzymatic RNA structure probing and EMSA in vitro","pmids":["16982637"],"confidence":"Medium","gaps":["No reconstitution of full processing complex with U7 snRNP was performed","Single lab, in vitro only"]},{"year":2009,"claim":"Identification of SLBP's requirement for histone mRNA nuclear export added a new function: SLBP knockdown causes nuclear retention of properly processed histone mRNA, linking SLBP to mRNP export beyond its known processing and translation roles.","evidence":"RNAi knockdown, RNA FISH, cell fractionation in U2OS cells","pmids":["19155325"],"confidence":"High","gaps":["The export receptor or adaptor recruited by SLBP was not identified","Whether SLBP directly contacts export machinery was untested"]},{"year":2012,"claim":"NMR mapping of the human SLBP RNA-binding domain defined two discrete RNA-contact sites and showed that TPNK phosphothreonine increases RNA affinity by slowing the off-rate, providing the first detailed kinetic and structural mechanism for phosphorylation-enhanced RNA binding.","evidence":"NMR spectroscopy and kinetic binding assays on human SLBP","pmids":["22439849"],"confidence":"High","gaps":["A full atomic-resolution structure of the SLBP–stem-loop complex was still lacking","Contributions of individual contact residues to in vivo function were not tested"]},{"year":2012,"claim":"Discovery that Pin1 and PP2A coordinately regulate SLBP dissociation from histone mRNA and subsequent degradation resolved how SLBP is removed from mRNPs at the end of S phase: Pin1 isomerizes phospho-Ser/Thr-Pro motifs to promote PP2A-mediated dephosphorylation of TPNK, releasing SLBP from RNA, and simultaneously stimulates polyubiquitination via the Ser20/Ser23 phosphodegron.","evidence":"In vitro dephosphorylation reconstitution (Pin1 + PP2A), ubiquitination assays, RNA stability measurements","pmids":["22907757"],"confidence":"High","gaps":["The kinase(s) responsible for Ser20/Ser23 phosphorylation were not identified","Order of events (RNA release versus ubiquitination) in living cells was not resolved"]},{"year":2012,"claim":"Analysis of Wolf-Hirschhorn syndrome patient cells demonstrated that SLBP haploinsufficiency causes defective chromatin assembly (reduced histone-chromatin association, increased MNase sensitivity), delayed S-phase progression, and DNA damage hypersensitivity, establishing a human disease connection.","evidence":"Patient-derived cell lines with 4p deletions, flow cytometry, MNase sensitivity, histone fractionation","pmids":["22328085"],"confidence":"Medium","gaps":["Other genes deleted in the 4p region could contribute to observed phenotypes","No rescue experiment with exogenous SLBP was performed"]},{"year":2013,"claim":"Crystal structures of the SLIP1–SLBP translation activation complex and SLIP1–eIF3g/DBP5 interactions revealed the molecular bridge between SLBP and the translation machinery: SLIP1 is a MIF4G-domain homodimer that binds SLBP and recruits eIF3 through a conserved SLIP1-binding motif, with phosphorylation-gated heterodimer/heterotetramer switching controlling complex assembly on histone mRNA.","evidence":"X-ray crystallography (2.5 Å and 3.25 Å), pull-down assays, analytical ultracentrifugation, RNA EMSA, in vivo histone mRNA quantification","pmids":["23804756","23286197"],"confidence":"High","gaps":["No structure of the full ternary SLBP–SLIP1–eIF3 complex on RNA","Contribution of DBP5 to histone mRNA translation in vivo was not assessed"]},{"year":2016,"claim":"Identification of two distinct ubiquitin ligase pathways targeting SLBP resolved the enzymology of its cell-cycle-regulated turnover: SCF–cyclin F degrades SLBP in G2 via a CY motif (with failure causing toxic H2A.X overexpression), while CRL4(WDR23) ubiquitylates SLBP non-degradatively to activate its processing function during S phase.","evidence":"Reciprocal Co-IP, CY motif mutagenesis, in vitro ubiquitylation reconstitution, polyribosome profiling, genetic knockdown","pmids":["27773672","27203182"],"confidence":"High","gaps":["The ubiquitin chain topology deposited by CRL4(WDR23) for activation was not determined","How CRL4(WDR23)-mediated ubiquitylation mechanistically activates processing was unknown"]},{"year":2017,"claim":"Discovery that FEM1A/B/C CUL2 ubiquitin ligases target SLBP via N-terminal degrons completed the degradation circuit: combined mutation of cyclin F and FEM1 interaction sites eliminates SLBP oscillation, demonstrating that multiple E3 ligases cooperate across different cell-cycle phases to ensure tight SLBP turnover.","evidence":"Co-immunoprecipitation, combined degron mutagenesis, conservation validated in C. elegans and Drosophila","pmids":["28118078"],"confidence":"High","gaps":["Relative contribution of each FEM1 family member in specific cell-cycle phases was not delineated","Structural basis of FEM1–SLBP degron recognition was not determined"]},{"year":2019,"claim":"Zebrafish Slbp loss-of-function mutants showed that SLBP is required for the proliferation-to-differentiation transition in the developing CNS, broadening its biological role beyond histone supply to cell-fate decisions.","evidence":"Forward genetic screen, genetic mapping, RNA-seq, in situ hybridization in zebrafish","pmids":["30695021"],"confidence":"Medium","gaps":["Whether the differentiation defect is a direct consequence of altered chromatin or secondary to cell-cycle arrest was not resolved","Single model organism"]},{"year":2021,"claim":"Identification of a Drosophila SLBP domain outside the RPD that is essential for histone gene transcription and mRNA deposition in oocytes revealed a separable transcriptional role for SLBP, distinct from its canonical 3'-end processing function.","evidence":"Deletion mutant analysis, in situ hybridization, genetic rescue in Drosophila oogenesis","pmids":["33408246"],"confidence":"Medium","gaps":["Whether this transcriptional role is conserved in vertebrates is unknown","The transcription factor or chromatin target of this domain was not identified"]},{"year":2025,"claim":"Discovery that Drosophila maternal histone mRNAs are uniquely polyadenylated with truncated stem-loops—requiring SLBP but not U7 snRNP—revealed a noncanonical SLBP-dependent processing pathway for maternally deposited histones.","evidence":"Genetic mutant analysis of SLBP and U7 snRNP in Drosophila, RNA-seq, polysome analysis","pmids":["40239992"],"confidence":"Medium","gaps":["Whether noncanonical polyadenylated histone mRNAs exist in vertebrate oocytes is unknown","The endonuclease generating the truncated stem-loop was not identified"]},{"year":null,"claim":"A high-resolution structure of the full human SLBP–stem-loop RNA complex, the mechanism by which CRL4(WDR23) ubiquitylation activates SLBP processing function, the identity of the nuclear export receptor recruited by SLBP, and whether SLBP's transcriptional role (seen in Drosophila oogenesis) is conserved in mammals remain unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No atomic-resolution structure of full-length SLBP bound to histone mRNA stem-loop","Mechanism of activating ubiquitylation by CRL4(WDR23) is undefined","Nuclear export pathway for SLBP-histone mRNP is unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[6,7,8,9,10,11,16,19]},{"term_id":"GO:0140098","term_label":"catalytic activity, acting on RNA","supporting_discovery_ids":[0,3,9,11]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[1,4,6]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[6,8]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[0,1,3,6,7,9,11,21]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[0,2,12,13,14]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[2,3,4,12]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[14]}],"complexes":["SLBP-SLIP1 translation activation complex","Histone mRNP"],"partners":["SLIP1","CCNF","WDR23","PIN1","FEM1A","FEM1B","FEM1C","EIF3G"],"other_free_text":[]},"mechanistic_narrative":"SLBP is the central post-transcriptional regulator of replication-dependent histone mRNAs, coupling histone biogenesis to S-phase progression through roles in 3'-end processing, nuclear export, translation, and mRNA degradation. Its RNA-binding domain is intrinsically disordered and folds upon phosphorylation-dependent binding to the conserved 3' stem-loop of histone mRNAs, where a phosphothreonine in the TPNK motif increases RNA affinity by stabilizing a hydrogen-bonding network and slowing the off-rate, while SLBP binding remodels the pre-mRNA to facilitate U7 snRNP recruitment for endonucleolytic cleavage [PMID:22439849, PMID:25379382, PMID:16982637]. SLBP accompanies processed histone mRNA to the cytoplasm for translation, recruiting the translation activator SLIP1—a MIF4G-domain homodimer that bridges SLBP to eIF3—through a phosphorylation-gated heterodimer assembly mechanism [PMID:23804756, PMID:23286197, PMID:19155325]. SLBP abundance is itself cell-cycle-regulated by at least three ubiquitin ligase systems—CRL4(WDR23) activating ubiquitylation during S phase, SCF–cyclin F targeting SLBP for G2 degradation via a CY motif, and FEM1-family CUL2 ligases mediating degradation in other phases—with Pin1/PP2A promoting SLBP dissociation from histone mRNA and subsequent polyubiquitination at the S/G2 boundary [PMID:27203182, PMID:27773672, PMID:28118078, PMID:22907757]. Haploinsufficiency of SLBP in Wolf-Hirschhorn syndrome patient cells causes defective chromatin assembly, delayed S-phase progression, and increased DNA damage sensitivity [PMID:22328085]."},"prefetch_data":{"uniprot":{"accession":"Q14493","full_name":"Histone RNA hairpin-binding protein","aliases":["Histone stem-loop-binding protein"],"length_aa":270,"mass_kda":31.3,"function":"RNA-binding protein involved in the histone pre-mRNA processing (PubMed:12588979, PubMed:19155325, PubMed:8957003, PubMed:9049306). Binds the stem-loop structure of replication-dependent histone pre-mRNAs and contributes to efficient 3'-end processing by stabilizing the complex between histone pre-mRNA and U7 small nuclear ribonucleoprotein (snRNP), via the histone downstream element (HDE) (PubMed:12588979, PubMed:19155325, PubMed:8957003, PubMed:9049306). Plays an important role in targeting mature histone mRNA from the nucleus to the cytoplasm and to the translation machinery (PubMed:12588979, PubMed:19155325, PubMed:8957003, PubMed:9049306). Stabilizes mature histone mRNA and could be involved in cell-cycle regulation of histone gene expression (PubMed:12588979, PubMed:19155325, PubMed:8957003, PubMed:9049306). Involved in the mechanism by which growing oocytes accumulate histone proteins that support early embryogenesis (By similarity). Binds to the 5' side of the stem-loop structure of histone pre-mRNAs (By similarity)","subcellular_location":"Cytoplasm; Nucleus","url":"https://www.uniprot.org/uniprotkb/Q14493/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/SLBP","classification":"Common Essential","n_dependent_lines":615,"n_total_lines":1208,"dependency_fraction":0.5091059602649006},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SLBP","total_profiled":1310},"omim":[{"mim_id":"617908","title":"ZINC FINGER PROTEIN 473; ZNF473","url":"https://www.omim.org/entry/617908"},{"mim_id":"612072","title":"MIF4G DOMAIN-CONTAINING PROTEIN; MIF4GD","url":"https://www.omim.org/entry/612072"},{"mim_id":"608739","title":"EXORIBONUCLEASE 1; ERI1","url":"https://www.omim.org/entry/608739"},{"mim_id":"602422","title":"STEM-LOOP BINDING PROTEIN; SLBP","url":"https://www.omim.org/entry/602422"},{"mim_id":"194190","title":"WOLF-HIRSCHHORN SYNDROME; WHS","url":"https://www.omim.org/entry/194190"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Nucleoli","reliability":"Supported"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/SLBP"},"hgnc":{"alias_symbol":["HBP"],"prev_symbol":[]},"alphafold":{"accession":"Q14493","domains":[{"cath_id":"1.10.8.1120","chopping":"131-196","consensus_level":"high","plddt":96.0906,"start":131,"end":196}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q14493","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q14493-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q14493-F1-predicted_aligned_error_v6.png","plddt_mean":70.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SLBP","jax_strain_url":"https://www.jax.org/strain/search?query=SLBP"},"sequence":{"accession":"Q14493","fasta_url":"https://rest.uniprot.org/uniprotkb/Q14493.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q14493/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q14493"}},"corpus_meta":[{"pmid":"11590435","id":"PMC_11590435","title":"Heparin-binding protein (HBP/CAP37): a missing link in neutrophil-evoked alteration of vascular permeability.","date":"2001","source":"Nature medicine","url":"https://pubmed.ncbi.nlm.nih.gov/11590435","citation_count":283,"is_preprint":false},{"pmid":"18787642","id":"PMC_18787642","title":"Neutrophil primary granule proteins HBP and HNP1-3 boost bacterial phagocytosis by human and murine macrophages.","date":"2008","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/18787642","citation_count":181,"is_preprint":false},{"pmid":"26068852","id":"PMC_26068852","title":"INNATE IMMUNITY. 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(HBP).","date":"2007","source":"Animal reproduction science","url":"https://pubmed.ncbi.nlm.nih.gov/17433582","citation_count":9,"is_preprint":false},{"pmid":"39962104","id":"PMC_39962104","title":"Accuracy of blood heparin-binding protein (HBP) for diagnosis bacteremia in patients with sepsis.","date":"2025","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/39962104","citation_count":8,"is_preprint":false},{"pmid":"36195852","id":"PMC_36195852","title":"Clinical value of serum sTREM-1 and HBP levels in combination with traditional inflammatory markers in diagnosing hospital-acquired pneumonia in elderly.","date":"2022","source":"BMC infectious diseases","url":"https://pubmed.ncbi.nlm.nih.gov/36195852","citation_count":8,"is_preprint":false},{"pmid":"8343598","id":"PMC_8343598","title":"Chromosomal locations of the genes for histones and a histone gene-binding protein family HBP-1 in common wheat.","date":"1993","source":"Plant molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/8343598","citation_count":8,"is_preprint":false},{"pmid":"21530274","id":"PMC_21530274","title":"New 3-, 8-disubstituted pyrazolo[5,1-c][1,2,4]benzotriazines useful for studying the interaction with the HBp-3 area (hydrogen bond point area) in the benzodiazepine site on the γ-aminobutyric acid type A (GABAA) receptor.","date":"2011","source":"Bioorganic & medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21530274","citation_count":8,"is_preprint":false},{"pmid":"40740652","id":"PMC_40740652","title":"Combinational Analysis of Metabolomic and O-GlcNAcylation Omics Reveals the HBP Metabolic Regulation of Chemoresistance via GFPT1/NR3C1 O-GlcNAcylation/GPX4 Axis.","date":"2025","source":"Research (Washington, D.C.)","url":"https://pubmed.ncbi.nlm.nih.gov/40740652","citation_count":7,"is_preprint":false},{"pmid":"30695021","id":"PMC_30695021","title":"Abrogation of Stem Loop Binding Protein (Slbp) function leads to a failure of cells to transition from proliferation to differentiation, retinal coloboma and midline axon guidance deficits.","date":"2019","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/30695021","citation_count":7,"is_preprint":false},{"pmid":"33408246","id":"PMC_33408246","title":"A region of SLBP outside the mRNA-processing domain is essential for deposition of histone mRNA into the Drosophila egg.","date":"2021","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/33408246","citation_count":7,"is_preprint":false},{"pmid":"10329492","id":"PMC_10329492","title":"Crystallographic characterization of a stress-induced multifunctional protein, rat HBP-23.","date":"1999","source":"Journal of structural biology","url":"https://pubmed.ncbi.nlm.nih.gov/10329492","citation_count":7,"is_preprint":false},{"pmid":"25379382","id":"PMC_25379382","title":"Contribution of protein phosphorylation to binding-induced folding of the SLBP-histone mRNA complex probed by phosphorus-31 NMR.","date":"2014","source":"FEBS open bio","url":"https://pubmed.ncbi.nlm.nih.gov/25379382","citation_count":7,"is_preprint":false},{"pmid":"7476857","id":"PMC_7476857","title":"Developmental and tissue-specific regulation of the gene for the wheat basic/leucine zipper protein HBP-1a(17) in transgenic Arabidopsis plants.","date":"1995","source":"Molecular & general genetics : MGG","url":"https://pubmed.ncbi.nlm.nih.gov/7476857","citation_count":7,"is_preprint":false},{"pmid":"35037047","id":"PMC_35037047","title":"53BP1-ACLY-SLBP-coordinated activation of replication-dependent histone biogenesis maintains genomic integrity.","date":"2022","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/35037047","citation_count":6,"is_preprint":false},{"pmid":"20083497","id":"PMC_20083497","title":"Identifying the functional part of heparin-binding protein (HBP) as a monocyte stimulator and the novel role of monocytes as HBP producers.","date":"2010","source":"Innate immunity","url":"https://pubmed.ncbi.nlm.nih.gov/20083497","citation_count":6,"is_preprint":false},{"pmid":"32806781","id":"PMC_32806781","title":"Insights into Mobile Genetic Elements of the Biocide-Degrading Bacterium Pseudomonas nitroreducens HBP-1.","date":"2020","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/32806781","citation_count":5,"is_preprint":false},{"pmid":"30910559","id":"PMC_30910559","title":"Molecular characterization and expression patterns of stem-loop binding protein (SLBP) genes in protogynous hermaphroditic grouper, Epinephelus coioides.","date":"2019","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/30910559","citation_count":5,"is_preprint":false},{"pmid":"3718538","id":"PMC_3718538","title":"Enhancement of affinity to receptors in the esterified glucocorticoid, hydrocortisone 17-butyrate 21-propionate (HBP), in the rat liver.","date":"1986","source":"Biochemical pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/3718538","citation_count":5,"is_preprint":false},{"pmid":"1926872","id":"PMC_1926872","title":"Quantification of human hepatic binding protein (HBP) via 99mTc-galactosyl-neoglycoalbumin (NGA) liver scintigraphy.","date":"1991","source":"Wiener klinische Wochenschrift","url":"https://pubmed.ncbi.nlm.nih.gov/1926872","citation_count":5,"is_preprint":false},{"pmid":"38815467","id":"PMC_38815467","title":"Multi-omics reveals the molecular mechanism of the combined toxic effects of PFOA and 4-HBP exposure in MCF-7 cells and the key player: mTORC1.","date":"2024","source":"Environment international","url":"https://pubmed.ncbi.nlm.nih.gov/38815467","citation_count":4,"is_preprint":false},{"pmid":"31216814","id":"PMC_31216814","title":"[Diagnostic value of HBP, PCT combined with APACHE Ⅱ score respectively in ventilator-associated pneumonia].","date":"2019","source":"Zhonghua yi xue za zhi","url":"https://pubmed.ncbi.nlm.nih.gov/31216814","citation_count":4,"is_preprint":false},{"pmid":"40239992","id":"PMC_40239992","title":"Maternal histone mRNAs are uniquely processed through polyadenylation in a Stem-Loop Binding Protein (SLBP) dependent manner.","date":"2025","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/40239992","citation_count":3,"is_preprint":false},{"pmid":"23860800","id":"PMC_23860800","title":"Glucan HBP-A increase type II collagen expression of chondrocytes in vitro and tissue engineered cartilage in vivo.","date":"2013","source":"Chinese journal of integrative medicine","url":"https://pubmed.ncbi.nlm.nih.gov/23860800","citation_count":3,"is_preprint":false},{"pmid":"28560279","id":"PMC_28560279","title":"Data for the generation of RNA spatiotemporal distributions and interpretation of Chk1 and SLBP protein depletion phenotypes during Drosophila embryogenesis.","date":"2017","source":"Data in brief","url":"https://pubmed.ncbi.nlm.nih.gov/28560279","citation_count":3,"is_preprint":false},{"pmid":"40772310","id":"PMC_40772310","title":"The HBP Pathway Inhibitor FR054 Enhances Temozolomide Sensitivity in Glioblastoma Cells by Promoting Ferroptosis and Inhibiting O-GlcNAcylation.","date":"2025","source":"CNS neuroscience & therapeutics","url":"https://pubmed.ncbi.nlm.nih.gov/40772310","citation_count":2,"is_preprint":false},{"pmid":"36803152","id":"PMC_36803152","title":"AZU1 (HBP/CAP37) and PRKCG (PKC-gamma) may be candidate genes affecting the severity of acute mountain sickness.","date":"2023","source":"BMC medical genomics","url":"https://pubmed.ncbi.nlm.nih.gov/36803152","citation_count":2,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":48902,"output_tokens":5327,"usd":0.113306},"stage2":{"model":"claude-opus-4-6","input_tokens":8868,"output_tokens":4108,"usd":0.22056},"total_usd":0.333866,"stage1_batch_id":"msgbatch_011rkcQdVV1RaFq9XhcG6df6","stage2_batch_id":"msgbatch_01RzgrJafdF4EWHhj5mNi6dh","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"SLBP is degraded at the end of S phase via phosphorylation of two threonines (T60 and T62 in the TTP sequence and a consensus cyclin binding site at aa 99-104). Mass spectrometry of purified SLBP from late S-phase cells confirmed phosphorylation of these residues, which triggers proteasomal degradation. Mutation of these residues stabilizes SLBP in G2/M. Nuclear extracts from G1 and G2 cells are deficient in histone pre-mRNA processing, which is restored by recombinant SLBP, demonstrating SLBP is the only cell cycle-regulated factor required for histone pre-mRNA processing.\",\n      \"method\": \"Mass spectrometry of purified SLBP, site-directed mutagenesis, nuclear extract reconstitution assay\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution, MS identification of phosphosites, mutagenesis validation\",\n      \"pmids\": [\"12588979\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"SLBP knockdown by RNAi in U2OS cells reveals that SLBP is required for nuclear export of histone mRNA. Reduced SLBP results in nuclear retention of properly processed histone mRNA, accumulation of cells in S phase, and loss of rapid histone mRNA degradation upon DNA replication inhibition, demonstrating a role for SLBP in histone mRNA export.\",\n      \"method\": \"RNAi knockdown, RNA FISH, cell fractionation, fluorescence microscopy\",\n      \"journal\": \"RNA (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KD with defined cellular phenotype (nuclear retention), multiple readouts\",\n      \"pmids\": [\"19155325\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Cyclin F (F-box protein, substrate recognition subunit of SCF complex) is identified as the G2 ubiquitin ligase for SLBP. SLBP interacts with cyclin F via an atypical CY motif; mutation of this motif prevents SLBP degradation in G2. Stable SLBP causes increased loading of H2AFX mRNA onto polyribosomes, elevated H2A.X, persistent γH2A.X signaling, and apoptosis upon genotoxic stress in G2.\",\n      \"method\": \"Co-immunoprecipitation, CY motif mutagenesis, polyribosome profiling, stable SLBP mutant expression\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP, mutagenesis, functional phenotype with multiple orthogonal readouts\",\n      \"pmids\": [\"27773672\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The CUL4 E3 ubiquitin ligase complex CRL4(WDR23) binds and ubiquitylates SLBP in vitro and in vivo. This ubiquitylation activates SLBP function in histone mRNA 3' end processing without affecting SLBP protein levels; loss of CRL4(WDR23) activity results in histone depletion and impaired DNA replication.\",\n      \"method\": \"In vitro ubiquitylation assay, co-immunoprecipitation, genetic knockdown, histone mRNA processing assay\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro ubiquitylation reconstitution plus in vivo validation with defined phenotype\",\n      \"pmids\": [\"27203182\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The prolyl isomerase Pin1 regulates SLBP degradation and histone mRNA stability. Pin1 promotes SLBP polyubiquitination via the Ser20/Ser23 phosphodegron. Pin1 together with PP2A can dephosphorylate phospho-Thr in the conserved TPNK sequence of the SLBP RNA binding domain in vitro, dissociating SLBP from the histone mRNA hairpin. Pin1 knockdown increases histone mRNA stability and accumulates SLBP in the nucleus.\",\n      \"method\": \"siRNA knockdown, in vitro dephosphorylation assay (Pin1 + PP2A), ubiquitination assay, RNA stability assay\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro biochemical reconstitution, siRNA with multiple readouts, moderate evidence\",\n      \"pmids\": [\"22907757\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Crystal structure of zebrafish SLIP1 bound to the translation-activation domain of SLBP determined at 2.5 Å. SLIP1 is a MIF4G-like homodimer that connects SLBP to translation initiation. A SLIP1-binding motif (SBM) was identified in eIF3g and DBP5; pull-down assays and crystal structure of SLIP1-DBP5 SBM confirmed these interactions. SLIP1 homodimerization and SBM-binding residues are conserved in CTIF.\",\n      \"method\": \"X-ray crystallography, pull-down assays, structure determination at 2.5 Å and 3.25 Å\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structures with biochemical validation by pulldown\",\n      \"pmids\": [\"23804756\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"SLBP is a component of the histone mRNP on polyribosomes. Anti-SLBP immunoprecipitation co-precipitates histone mRNA from polyribosomes. When DNA replication is inhibited, histone mRNAs are rapidly degraded but SLBP remains constant and relocalizes to the nucleus, remaining active in RNA binding and histone pre-mRNA processing.\",\n      \"method\": \"Polyribosome fractionation, co-immunoprecipitation of RNA, subcellular fractionation\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — polyribosome fractionation + RNA co-IP + functional processing assays\",\n      \"pmids\": [\"15358832\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"SLBP has two binding sites for the histone mRNA hairpin within its RNA binding domain: a helix-turn-helix motif (Glu129–Val158) recognizing unpaired uridines in the stem-loop, and a second site (Arg180–Pro200) recognizing the second G-C base pair. Threonine phosphorylation at the conserved TPNK sequence increases SLBP affinity for histone mRNA by slowing off-rate; the adjacent proline acts as a hinge regulating the second binding site.\",\n      \"method\": \"NMR spectroscopy, kinetic binding assays, phosphorylation analysis\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — NMR structural mapping with kinetic validation and mutagenesis\",\n      \"pmids\": [\"22439849\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Assembly of the SLIP1-SLBP complex on histone mRNA requires sequential binding: phosphorylated SLBP binds the histone mRNA stem-loop first, then SLIP1 associates to form an active ternary complex. Unphosphorylated SLBP and SLIP1 form an inactive 2:2 heterotetramer that cannot bind histone mRNA; phosphorylation at Thr171 promotes dissociation to the active heterodimer. A single-point SLIP1 mutant near the homodimer interface abolished SLBP interaction and reduced histone mRNA in vivo.\",\n      \"method\": \"Analytical ultracentrifugation, baculovirus phosphorylated SLBP, alanine scanning mutagenesis, RNA EMSA, in vivo histone mRNA quantification\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — biophysical reconstitution + mutagenesis + in vivo validation\",\n      \"pmids\": [\"23286197\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"SLBP binding to the 3'-UTR of histone pre-mRNA H4-12 induces structural rearrangements that open the HDE hairpin, making it accessible for U7 snRNA anchoring. RNA structure probing and EMSA demonstrated that SLBP facilitates U7 snRNP binding to the pre-mRNA.\",\n      \"method\": \"RNA structure probing (chemical/enzymatic), EMSA\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vitro RNA probing and EMSA, single lab\",\n      \"pmids\": [\"16982637\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"The N-terminal domain of Drosophila SLBP is intrinsically disordered with nascent helical structure at physiological conditions. NMR characterization shows four regions with helical propensity but no well-defined tertiary fold in the absence of RNA, consistent with a disordered-to-ordered transition upon RNA binding.\",\n      \"method\": \"NMR spectroscopy (15N, 13C labeling), circular dichroism\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — complete NMR characterization of domain structure\",\n      \"pmids\": [\"15260482\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Phosphorylation of C-terminal serines in the SLBP RNA binding and processing domain (RPD) is necessary for histone pre-mRNA processing in Drosophila. Both serine phosphorylation and RNA binding are required for proper folding of the RPD; the electrostatic effect of phosphorylation can be partially mimicked by serine-to-glutamate mutations.\",\n      \"method\": \"31P NMR, circular dichroism, in vitro processing assay, phosphomimetic mutagenesis\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — NMR, mutagenesis, and in vitro processing assay\",\n      \"pmids\": [\"15260483\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"FEM1A, FEM1B, and FEM1C (VHL-box CUL2-RING E3 ubiquitin ligase substrate recognition subunits) interact with SLBP via distinct degrons in SLBP's N-terminus and mediate SLBP degradation. An SLBP mutant unable to interact with cyclin F plus all three FEM1 proteins is expressed at higher levels and does not oscillate during the cell cycle. FEM1-SLBP ortholog interactions are conserved in C. elegans and D. melanogaster.\",\n      \"method\": \"Co-immunoprecipitation, mutagenesis (combined degron mutants), C. elegans genetic depletion of FEM1\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP, mutagenesis, evolutionary conservation validated in two model organisms\",\n      \"pmids\": [\"28118078\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"SLBP is required for efficient DNA replication. RNAi-mediated removal of SLBP increases the number of cells in S phase and causes slow progression through S phase upon release from a double-thymidine block. Re-expression of an RNAi-resistant SLBP restores proper S-phase progression, demonstrating the effect is specifically due to SLBP loss.\",\n      \"method\": \"RNAi, rescue with RNAi-resistant SLBP, double-thymidine block cell cycle analysis\",\n      \"journal\": \"Biochemical Society transactions\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — RNAi with genetic rescue, single lab\",\n      \"pmids\": [\"15916543\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Haploinsufficiency of SLBP in Wolf-Hirschhorn syndrome patient-derived cells causes delayed S-to-M phase progression, reduced DNA replication, altered chromatin assembly (reduced histone-chromatin association, elevated soluble chaperone-bound histone H3, increased MNase sensitivity), and increased camptothecin sensitivity.\",\n      \"method\": \"Patient-derived cell lines with variable 4p deletions, flow cytometry, MNase sensitivity assay, histone-chromatin fractionation\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — human genetic model with multiple cellular phenotypes, correlative but mechanistically informative\",\n      \"pmids\": [\"22328085\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"53BP1 acts as a molecular scaffold for NDPK-mediated phosphorylation of ATP-citrate lyase (ACLY), enhancing ACLY activity, global histone acetylation, and transcriptome-wide gene expression changes. SLBP expression is dependent on 53BP1-ACLY-controlled acetylation at the SLBP promoter, placing SLBP downstream in a 53BP1-ACLY-SLBP axis that coordinates replication-dependent histone biogenesis.\",\n      \"method\": \"Co-immunoprecipitation, ChIP, ACLY activity assay, transcriptomic analysis\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP, ChIP, functional assays; single lab with multiple methods\",\n      \"pmids\": [\"35037047\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"31P NMR demonstrates that a phosphothreonine in the RNA binding domain of SLBP exhibits torsional strain and participates in a hydrogen-bonding network; phosphorylation at this residue promotes assembly of the SLBP-RNA complex through phosphate-coupled folding of an intrinsically disordered region.\",\n      \"method\": \"31P NMR spectroscopy\",\n      \"journal\": \"FEBS open bio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 method (NMR) but single lab, single technique\",\n      \"pmids\": [\"25379382\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Loss of Slbp function in zebrafish (eisspalte mutants) causes failure of cells to transition from proliferation to differentiation, retinal coloboma, midline axon guidance deficits, and altered expression of neuronal differentiation and axon guidance genes. Cells throughout the CNS remain in the cell cycle at stages when post-mitotic differentiation normally occurs.\",\n      \"method\": \"Forward genetic screen, genetic mapping, RNAseq, in situ hybridization\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — zebrafish ortholog loss-of-function with defined cellular phenotypes; ortholog confirmed by domain/function conservation\",\n      \"pmids\": [\"30695021\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In Drosophila stage 10B oocytes, a region of SLBP outside the mRNA-processing domain (overlapping a putative nuclear localization sequence) is essential for histone mRNA deposition into the oocyte and for histone gene transcription. A 10-amino-acid deletion or NLS mutations prevent histone gene transcription in stage 10B without affecting S-phase processing function.\",\n      \"method\": \"SLBP deletion mutant analysis, in situ hybridization, genetic rescue in Drosophila\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — defined domain mapping by mutagenesis in vivo in Drosophila ortholog\",\n      \"pmids\": [\"33408246\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Yeast three-hybrid system analysis of human SLBP identified critical residues in the RNA binding domain required for histone hairpin recognition. Both the core RBD and flanking N- and C-terminal domains contribute to RNA discrimination.\",\n      \"method\": \"Yeast three-hybrid system, negative and positive selection screens\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — yeast three-hybrid, single lab, no structural validation\",\n      \"pmids\": [\"14706861\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Nickel and cadmium compounds deplete SLBP mRNA and protein levels, resulting in increased polyadenylated canonical histone H3.1 mRNA. SLBP protein depletion is reversed by proteasome inhibition. Rescue of SLBP mRNA and protein by epigenetic modifiers suggests nickel acts through epigenetic mechanisms to reduce SLBP expression.\",\n      \"method\": \"Western blot, qRT-PCR, proteasome inhibitor treatment, epigenetic modifier rescue\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single lab, indirect mechanistic inference, no direct biochemical reconstitution\",\n      \"pmids\": [\"28306745\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In Drosophila, maternal histone mRNAs are uniquely polyadenylated and have a truncated 3' stem-loop. This noncanonical 3'-end processing requires SLBP but not U7 snRNP during oogenesis. Maternal histone transcripts undergo cytoplasmic poly(A) elongation by Wisp for stabilization and translation, and their translation is activated upon loss of embryonic linker histone dBigH1.\",\n      \"method\": \"Genetic mutant analysis (SLBP and U7 snRNP mutants in Drosophila), RNA sequencing, polysome analysis, in situ hybridization\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Drosophila ortholog genetics with multiple molecular readouts; single study\",\n      \"pmids\": [\"40239992\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SLBP (stem-loop binding protein) is an intrinsically disordered protein that binds the conserved 3' stem-loop of replication-dependent histone mRNAs, where phosphorylation of a threonine in the TPNK motif of its RNA-binding domain promotes high-affinity RNA binding and correct domain folding; SLBP is the sole cell cycle-regulated factor required for histone pre-mRNA 3'-end processing, participates in nuclear export, translation (via SLIP1/eIF3 interaction), and mRNA degradation of histone mRNAs, and its own abundance is cell-cycle-regulated through sequential ubiquitin-mediated degradation executed by CRL4(WDR23) (activating ubiquitylation), SCF-cyclin F (G2 degradation via a CY motif), and FEM1 family CUL2 ligases (other cell cycle phases), with Pin1/PP2A additionally coordinating SLBP dissociation from histone mRNA and SLBP ubiquitination at the end of S phase.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"SLBP is the central post-transcriptional regulator of replication-dependent histone mRNAs, coupling histone biogenesis to S-phase progression through roles in 3'-end processing, nuclear export, translation, and mRNA degradation. Its RNA-binding domain is intrinsically disordered and folds upon phosphorylation-dependent binding to the conserved 3' stem-loop of histone mRNAs, where a phosphothreonine in the TPNK motif increases RNA affinity by stabilizing a hydrogen-bonding network and slowing the off-rate, while SLBP binding remodels the pre-mRNA to facilitate U7 snRNP recruitment for endonucleolytic cleavage [PMID:22439849, PMID:25379382, PMID:16982637]. SLBP accompanies processed histone mRNA to the cytoplasm for translation, recruiting the translation activator SLIP1—a MIF4G-domain homodimer that bridges SLBP to eIF3—through a phosphorylation-gated heterodimer assembly mechanism [PMID:23804756, PMID:23286197, PMID:19155325]. SLBP abundance is itself cell-cycle-regulated by at least three ubiquitin ligase systems—CRL4(WDR23) activating ubiquitylation during S phase, SCF–cyclin F targeting SLBP for G2 degradation via a CY motif, and FEM1-family CUL2 ligases mediating degradation in other phases—with Pin1/PP2A promoting SLBP dissociation from histone mRNA and subsequent polyubiquitination at the S/G2 boundary [PMID:27203182, PMID:27773672, PMID:28118078, PMID:22907757]. Haploinsufficiency of SLBP in Wolf-Hirschhorn syndrome patient cells causes defective chromatin assembly, delayed S-phase progression, and increased DNA damage sensitivity [PMID:22328085].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Establishing that SLBP is the sole cell-cycle-regulated processing factor answered how histone pre-mRNA 3'-end cleavage is restricted to S phase: phosphorylation of T60/T62 triggers proteasomal degradation at the S/G2 boundary, and recombinant SLBP restores processing activity to G1 or G2 nuclear extracts that otherwise lack it.\",\n      \"evidence\": \"Mass spectrometry of purified SLBP, phosphosite mutagenesis, nuclear extract reconstitution in human cells\",\n      \"pmids\": [\"12588979\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the E3 ligase recognizing the T60/T62 phosphodegron was unknown\", \"Whether additional post-translational modifications govern SLBP stability remained open\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Structural characterization of the RNA-binding domain resolved how an intrinsically disordered protein achieves specific RNA recognition: NMR showed the N-terminal/RBD regions are disordered in isolation but adopt nascent helical structure, and phosphorylation of C-terminal serines in the RPD is required for proper domain folding and processing activity.\",\n      \"evidence\": \"NMR spectroscopy (Drosophila SLBP), 31P NMR, circular dichroism, in vitro processing assays, phosphomimetic mutagenesis\",\n      \"pmids\": [\"15260482\", \"15260483\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"High-resolution structure of the SLBP–RNA complex was not yet available\", \"Whether phosphorylation-coupled folding operates identically in human SLBP was untested\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Demonstrating that SLBP remains on histone mRNA on polyribosomes established its post-processing cytoplasmic role: SLBP co-immunoprecipitates with histone mRNA from polyribosome fractions and relocalizes to the nucleus upon replication inhibition while remaining functional for RNA binding.\",\n      \"evidence\": \"Polyribosome fractionation and RNA co-immunoprecipitation in mammalian cells\",\n      \"pmids\": [\"15358832\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The mechanism by which SLBP stimulates translation was unclear\", \"How SLBP relocalizes to the nucleus upon replication stress was undefined\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Linking SLBP to DNA replication efficiency showed that its role extends beyond RNA metabolism: RNAi depletion of SLBP slows S-phase progression, rescued by RNAi-resistant SLBP re-expression.\",\n      \"evidence\": \"RNAi knockdown with genetic rescue, double-thymidine block, flow cytometry in human cells\",\n      \"pmids\": [\"15916543\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether the replication defect is due to histone shortage versus other SLBP functions was not distinguished\", \"Single lab study\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"RNA structure probing revealed that SLBP binding remodels the histone pre-mRNA substrate to expose the histone downstream element for U7 snRNP, explaining how SLBP catalytically facilitates the processing reaction beyond simple stem-loop recognition.\",\n      \"evidence\": \"Chemical/enzymatic RNA structure probing and EMSA in vitro\",\n      \"pmids\": [\"16982637\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No reconstitution of full processing complex with U7 snRNP was performed\", \"Single lab, in vitro only\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Identification of SLBP's requirement for histone mRNA nuclear export added a new function: SLBP knockdown causes nuclear retention of properly processed histone mRNA, linking SLBP to mRNP export beyond its known processing and translation roles.\",\n      \"evidence\": \"RNAi knockdown, RNA FISH, cell fractionation in U2OS cells\",\n      \"pmids\": [\"19155325\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The export receptor or adaptor recruited by SLBP was not identified\", \"Whether SLBP directly contacts export machinery was untested\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"NMR mapping of the human SLBP RNA-binding domain defined two discrete RNA-contact sites and showed that TPNK phosphothreonine increases RNA affinity by slowing the off-rate, providing the first detailed kinetic and structural mechanism for phosphorylation-enhanced RNA binding.\",\n      \"evidence\": \"NMR spectroscopy and kinetic binding assays on human SLBP\",\n      \"pmids\": [\"22439849\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"A full atomic-resolution structure of the SLBP–stem-loop complex was still lacking\", \"Contributions of individual contact residues to in vivo function were not tested\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Discovery that Pin1 and PP2A coordinately regulate SLBP dissociation from histone mRNA and subsequent degradation resolved how SLBP is removed from mRNPs at the end of S phase: Pin1 isomerizes phospho-Ser/Thr-Pro motifs to promote PP2A-mediated dephosphorylation of TPNK, releasing SLBP from RNA, and simultaneously stimulates polyubiquitination via the Ser20/Ser23 phosphodegron.\",\n      \"evidence\": \"In vitro dephosphorylation reconstitution (Pin1 + PP2A), ubiquitination assays, RNA stability measurements\",\n      \"pmids\": [\"22907757\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The kinase(s) responsible for Ser20/Ser23 phosphorylation were not identified\", \"Order of events (RNA release versus ubiquitination) in living cells was not resolved\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Analysis of Wolf-Hirschhorn syndrome patient cells demonstrated that SLBP haploinsufficiency causes defective chromatin assembly (reduced histone-chromatin association, increased MNase sensitivity), delayed S-phase progression, and DNA damage hypersensitivity, establishing a human disease connection.\",\n      \"evidence\": \"Patient-derived cell lines with 4p deletions, flow cytometry, MNase sensitivity, histone fractionation\",\n      \"pmids\": [\"22328085\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Other genes deleted in the 4p region could contribute to observed phenotypes\", \"No rescue experiment with exogenous SLBP was performed\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Crystal structures of the SLIP1–SLBP translation activation complex and SLIP1–eIF3g/DBP5 interactions revealed the molecular bridge between SLBP and the translation machinery: SLIP1 is a MIF4G-domain homodimer that binds SLBP and recruits eIF3 through a conserved SLIP1-binding motif, with phosphorylation-gated heterodimer/heterotetramer switching controlling complex assembly on histone mRNA.\",\n      \"evidence\": \"X-ray crystallography (2.5 Å and 3.25 Å), pull-down assays, analytical ultracentrifugation, RNA EMSA, in vivo histone mRNA quantification\",\n      \"pmids\": [\"23804756\", \"23286197\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No structure of the full ternary SLBP–SLIP1–eIF3 complex on RNA\", \"Contribution of DBP5 to histone mRNA translation in vivo was not assessed\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identification of two distinct ubiquitin ligase pathways targeting SLBP resolved the enzymology of its cell-cycle-regulated turnover: SCF–cyclin F degrades SLBP in G2 via a CY motif (with failure causing toxic H2A.X overexpression), while CRL4(WDR23) ubiquitylates SLBP non-degradatively to activate its processing function during S phase.\",\n      \"evidence\": \"Reciprocal Co-IP, CY motif mutagenesis, in vitro ubiquitylation reconstitution, polyribosome profiling, genetic knockdown\",\n      \"pmids\": [\"27773672\", \"27203182\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The ubiquitin chain topology deposited by CRL4(WDR23) for activation was not determined\", \"How CRL4(WDR23)-mediated ubiquitylation mechanistically activates processing was unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Discovery that FEM1A/B/C CUL2 ubiquitin ligases target SLBP via N-terminal degrons completed the degradation circuit: combined mutation of cyclin F and FEM1 interaction sites eliminates SLBP oscillation, demonstrating that multiple E3 ligases cooperate across different cell-cycle phases to ensure tight SLBP turnover.\",\n      \"evidence\": \"Co-immunoprecipitation, combined degron mutagenesis, conservation validated in C. elegans and Drosophila\",\n      \"pmids\": [\"28118078\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contribution of each FEM1 family member in specific cell-cycle phases was not delineated\", \"Structural basis of FEM1–SLBP degron recognition was not determined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Zebrafish Slbp loss-of-function mutants showed that SLBP is required for the proliferation-to-differentiation transition in the developing CNS, broadening its biological role beyond histone supply to cell-fate decisions.\",\n      \"evidence\": \"Forward genetic screen, genetic mapping, RNA-seq, in situ hybridization in zebrafish\",\n      \"pmids\": [\"30695021\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether the differentiation defect is a direct consequence of altered chromatin or secondary to cell-cycle arrest was not resolved\", \"Single model organism\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identification of a Drosophila SLBP domain outside the RPD that is essential for histone gene transcription and mRNA deposition in oocytes revealed a separable transcriptional role for SLBP, distinct from its canonical 3'-end processing function.\",\n      \"evidence\": \"Deletion mutant analysis, in situ hybridization, genetic rescue in Drosophila oogenesis\",\n      \"pmids\": [\"33408246\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether this transcriptional role is conserved in vertebrates is unknown\", \"The transcription factor or chromatin target of this domain was not identified\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Discovery that Drosophila maternal histone mRNAs are uniquely polyadenylated with truncated stem-loops—requiring SLBP but not U7 snRNP—revealed a noncanonical SLBP-dependent processing pathway for maternally deposited histones.\",\n      \"evidence\": \"Genetic mutant analysis of SLBP and U7 snRNP in Drosophila, RNA-seq, polysome analysis\",\n      \"pmids\": [\"40239992\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether noncanonical polyadenylated histone mRNAs exist in vertebrate oocytes is unknown\", \"The endonuclease generating the truncated stem-loop was not identified\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A high-resolution structure of the full human SLBP–stem-loop RNA complex, the mechanism by which CRL4(WDR23) ubiquitylation activates SLBP processing function, the identity of the nuclear export receptor recruited by SLBP, and whether SLBP's transcriptional role (seen in Drosophila oogenesis) is conserved in mammals remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No atomic-resolution structure of full-length SLBP bound to histone mRNA stem-loop\", \"Mechanism of activating ubiquitylation by CRL4(WDR23) is undefined\", \"Nuclear export pathway for SLBP-histone mRNP is unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [6, 7, 8, 9, 10, 11, 16, 19]},\n      {\"term_id\": \"GO:0140098\", \"supporting_discovery_ids\": [0, 3, 9, 11]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [1, 4, 6]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [6, 8]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [0, 1, 3, 6, 7, 9, 11, 21]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [0, 2, 12, 13, 14]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [2, 3, 4, 12]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [14]}\n    ],\n    \"complexes\": [\n      \"SLBP-SLIP1 translation activation complex\",\n      \"Histone mRNP\"\n    ],\n    \"partners\": [\n      \"SLIP1\",\n      \"CCNF\",\n      \"WDR23\",\n      \"PIN1\",\n      \"FEM1A\",\n      \"FEM1B\",\n      \"FEM1C\",\n      \"EIF3G\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}