{"gene":"PIK3R4","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":1993,"finding":"Vps15 protein kinase forms a hetero-oligomeric membrane-associated complex with the Vps34 PI 3-kinase; Vps15 is responsible for recruiting Vps34 to intracellular membranes, and an intact Vps15 kinase domain is required for activation of Vps34 PI 3-kinase activity.","method":"Chemical cross-linking, native immunoprecipitation, subcellular fractionation, sucrose density gradients, kinase domain mutagenesis, genetic suppression assay","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal methods (co-IP, fractionation, mutagenesis, genetic suppression) in a foundational study; independently replicated in subsequent work","pmids":["8387919"],"is_preprint":false},{"year":1995,"finding":"Active Vps15p kinase domain is necessary for physical association with Vps34p and for recruitment of Vps34p to the membrane; catalytically inactive Vps15p mutants cannot associate with Vps34p. Functional Vps15p-Vps34p complex is absolutely required for efficient vacuolar protein delivery, as shown by temperature-conditional alleles causing loss of PI(3)P and missorting of soluble vacuolar proteins.","method":"Temperature-conditional allele analysis, in vivo PtdIns(3)P measurements, genetic dominant-negative analysis, mutagenesis of kinase/lipid kinase domains","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple allele types, PI3P quantification, and genetic epistasis; extends and replicates findings from PMID:8387919","pmids":["7721937"],"is_preprint":false},{"year":1991,"finding":"Alterations of conserved protein kinase residues in Vps15p biologically inactivate the protein, blocking vacuolar sorting of soluble hydrolases (CPY, PrA) but not the membrane protein alkaline phosphatase. C-terminal truncations of Vps15p abolish in vivo phosphorylation of Vps15p and cause a temperature-conditional vacuolar protein sorting defect, suggesting autophosphorylation is required for full activity.","method":"Site-directed mutagenesis of conserved kinase residues, in vivo 32P-phosphorylation assay, temperature-shift experiments, pulse-chase sorting assay","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — active-site mutagenesis with multiple in vivo functional readouts; foundational mechanistic study","pmids":["1756716"],"is_preprint":false},{"year":2009,"finding":"The Vps15 WD-repeat domain forms a seven-bladed beta-propeller resembling a G-protein beta subunit and is sufficient to bind the G protein alpha subunit Gpa1 (preferentially GDP-bound) and Atg14. The kinase and intermediate domains of Vps15 additionally contribute to Gpa1 binding and are necessary for G protein signaling at endosomes.","method":"X-ray crystal structure of the Vps15 WD domain, binding assays (Gpa1-Vps15 interaction), domain deletion analysis, G protein signaling assays","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with functional domain dissection in a single study; no independent replication in corpus","pmids":["19445518"],"is_preprint":false},{"year":2010,"finding":"A specific PI3K-III sub-complex containing VPS15, VPS34, Beclin 1, UVRAG and BIF-1 (but not ATG14L) regulates endocytic receptor degradation and cytokinesis in mammalian cells.","method":"siRNA depletion of individual subunits, high-content microscopy-based assays for receptor degradation and cytokinesis, midbody localization of UVRAG and BIF-1","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown with two independent cellular phenotypic readouts; single lab, no biochemical reconstitution of complex","pmids":["20643123"],"is_preprint":false},{"year":2008,"finding":"Drosophila Vps15 is required for starvation-induced autophagy in fat body and gut; loss of vps15 leads to accumulation of ubiquitin- and Ref(2)P/p62-positive, partially detergent-insoluble protein aggregates, establishing Vps15 as essential for autophagic clearance of protein aggregates in a multicellular organism.","method":"Drosophila deletion mutant, GFP-Atg8a fluorescence microscopy, electron microscopy, biochemical fractionation, Western blot, immuno-electron microscopy","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic loss-of-function with multiple orthogonal readouts (fluorescence, EM, biochemical fractionation) establishing pathway position","pmids":["18326940"],"is_preprint":false},{"year":2013,"finding":"Vps15 is required for lysosomal function in skeletal muscle; muscle-specific Vps15 knockout mice show accumulation of autophagosomes, p62, LC3, and Lamp2-positive vesicles, and develop autophagic vacuolar myopathy. Importantly, autophagosome formation (LC3-positive) and mTOR activation are maintained in Vps15-deficient cells, indicating Vps15/Vps34 is specifically required downstream (lysosomal fusion/degradation) rather than for autophagosome initiation per se.","method":"Conditional (muscle-specific) Vps15 knockout mouse, immunofluorescence, electron microscopy, LC3/p62/LAMP2 Western blot, creatine kinase assay, Vps15 rescue by overexpression in Danon disease myoblasts","journal":"EMBO molecular medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean conditional KO with multiple orthogonal phenotypic readouts and rescue experiment; defines specific step in autophagy pathway","pmids":["23630012"],"is_preprint":false},{"year":2016,"finding":"VPS15 interacts with the golgin GM130 at the cis-Golgi, forming a complex devoid of VPS34, and is required for IFT20 release from the Golgi for transport to the primary cilium. A patient missense mutation VPS15-R998Q impairs this Golgi trafficking function without fully disrupting VPS34-dependent activities. VPS15 regulates primary cilium length in human fibroblasts.","method":"Missense mutation identification in ciliopathy patients, co-immunoprecipitation of VPS15 with GM130, subcellular localization (Golgi), humanized yeast complementation assay, IFT20 localization in patient fibroblasts, zebrafish cilia assay","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal co-IP, patient mutation functional validation in yeast and fibroblasts, zebrafish in vivo phenotype; multiple orthogonal methods","pmids":["27882921"],"is_preprint":false},{"year":2018,"finding":"A hypomorphic Vps15 mutation in mice causes defects in endosomal-lysosomal trafficking and autophagy, resulting in upregulation of Nischarin, which inhibits Pak1 signaling, thereby disrupting neuronal migration and causing hippocampal pyramidal cell layer defects. Complete Vps15 ablation causes accumulation of autophagic substrates, apoptosis, and severe cortical atrophy.","method":"ENU-induced mouse mutant, conditional knockout, neuronal migration assays, Western blot for Nischarin and Pak1 phosphorylation, epistasis between Vps15, Nischarin, and Pak1 pathways","journal":"Nature neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic loss-of-function in mouse with epistasis establishing Vps15→Nischarin→Pak1 signaling axis; confirmed in human patients","pmids":["29311744"],"is_preprint":false},{"year":2021,"finding":"ULK1/2 kinases phosphorylate VPS15 at six sites (including serine 861 as the major site); mutation of these sites reduces VPS34 activity in vitro and impairs autophagosome formation in cells. VPS15 knockout also reveals ULK-dependent starvation-independent accumulation of ULK substrates and kinase activity-regulated recruitment of autophagy proteins to ubiquitin-positive structures.","method":"Unbiased phosphoproteomics in Ulk1/2 double-knockout MEFs, in vitro VPS34 kinase assay with VPS15 phosphosite mutants, autophagosome formation assays, VPS15 knockout cell lines","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — phosphoproteomics discovery combined with in vitro kinase reconstitution assay and cellular phenotypic validation; multiple orthogonal methods","pmids":["34121209"],"is_preprint":false},{"year":2025,"finding":"Cryo-EM structure of the PI3KC3-C1 complex reveals that the VPS15 pseudokinase domain binds GTP and sequesters its covalently-linked N-terminal myristate in the N-lobe, stabilizing the inactive conformation of VPS34. Upon membrane binding (activation), myristate is liberated, disrupting the inhibitory interaction and enabling VPS34 to catalyze PI3P production on membranes.","method":"Cryo-electron microscopy of full PI3KC3-C1 complex, structural analysis of pseudokinase-GTP interaction, myristate sequestration/release mechanism, functional validation of VPS34 activation","journal":"Science (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1 / Strong — high-resolution cryo-EM structure with detailed mechanistic insight into activation pathway; single study but multiple structural and functional validations","pmids":["39913640"],"is_preprint":false},{"year":1999,"finding":"Pichia pastoris Vps15 (PpVPS15) is required at an early stage of selective peroxisome autophagy (pexophagy); deletion of PpVPS15 prevents vacuolar uptake of peroxisomes upon glucose or ethanol exposure.","method":"Gene deletion in Pichia pastoris, measurement of peroxisomal marker enzyme levels, electron microscopy of peroxisome uptake","journal":"Current genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — clean genetic deletion with EM and biochemical readouts but single study in a divergent yeast species (Pichia pastoris)","pmids":["10591966"],"is_preprint":false},{"year":2014,"finding":"Drosophila Vps15 is required for autophagy induced by multiple stresses (nutrient deprivation, hypoxia, oxidative stress) and for developmentally programmed autophagy in fat body, intestine, and salivary gland. Additionally, Vps15 is necessary for efficient protein secretion from salivary glands, demonstrating a role in secretory vesicle trafficking beyond autophagy.","method":"Drosophila vps15 genetic mutants, autophagy markers (Atg8, lysotracker), electron microscopy, salivary gland secretion assay","journal":"Cell death and differentiation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic loss-of-function with multiple tissue/stress contexts and orthogonal readouts; single lab","pmids":["25342466"],"is_preprint":false},{"year":2019,"finding":"VPS15 knockdown in HUVECs inhibits AngII-induced autophagy and reduces phosphorylation of PDK1 and PKC substrates, while re-expression of Vps15 rescues autophagy; PDK1 and PKC inhibitors phenocopy Vps15 knockdown, placing Vps15 upstream of a PDK1/PKC signaling axis in autophagy regulation.","method":"shRNA knockdown of Vps15, MDC staining, LC3-II/I Western blot, pharmacological inhibition of PDK1/PKC, rescue by Vps15 re-expression, flow cytometry for apoptosis","journal":"Life sciences","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single cell type, indirect pathway placement via inhibitor pharmacology without direct biochemical demonstration of VPS15-PDK1 interaction","pmids":["31356904"],"is_preprint":false},{"year":2025,"finding":"Loss of Vps15 (core PI3K-III subunit) in Drosophila wing imaginal discs selectively impairs an endocytosis-dependent pool of Wingless (Wg) secretion, causing apical accumulation of Wg in secreting cells, while a glypican-mediated Wg pool is unaffected. Evi/Wls cargo receptor undergoes proteasome-dependent degradation rather than accumulation in PI3K-III mutant cells.","method":"In vivo CRISPR-Cas9 kinome/phosphatome screen, endogenously fluorescently tagged Wg, super-resolution microscopy, ex vivo pharmacological treatments (proteasome inhibitor)","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo genetic screen with super-resolution imaging and pharmacological validation; preprint, not yet peer-reviewed","pmids":["bio_10.1101_2025.05.20.655092"],"is_preprint":true}],"current_model":"VPS15 (PIK3R4) is a pseudokinase/regulatory subunit that forms the core of the class III PI3K complex with VPS34; its pseudokinase domain binds GTP and sequesters an N-terminal myristate to maintain the complex in an autoinhibited cytosolic state, and upon membrane engagement myristate release activates VPS34 to produce PI3P, which drives vesicular trafficking, vacuolar/lysosomal protein sorting, autophagosome formation, endosomal maturation, and cytokinesis; VPS15 also assembles VPS34-independent complexes (e.g., with GM130 at the Golgi for ciliary cargo sorting) and is phosphorylated by ULK1/2 to modulate VPS34 activity during autophagy initiation."},"narrative":{"mechanistic_narrative":"PIK3R4 (VPS15) is the regulatory pseudokinase subunit at the core of the class III PI3-kinase complex, where it recruits and activates the VPS34 lipid kinase to drive PI3P-dependent vacuolar/lysosomal protein sorting, autophagy, endosomal trafficking, and cytokinesis [PMID:8387919, PMID:7721937]. It forms a hetero-oligomeric membrane-associated complex with VPS34, and its protein-kinase-domain integrity—originally characterized in yeast through active-site mutagenesis and conditional alleles—is required for both physical association with VPS34 and for activation of VPS34 lipid kinase activity, with loss of function causing depletion of PI3P and missorting of soluble vacuolar hydrolases [PMID:8387919, PMID:7721937, PMID:1756716]. Structurally, the VPS15 WD-repeat domain folds into a seven-bladed beta-propeller that resembles a G-protein beta subunit [PMID:19445518], while cryo-EM of the PI3KC3-C1 complex shows that the VPS15 pseudokinase domain binds GTP and sequesters its covalently linked N-terminal myristate to stabilize an autoinhibited VPS34 conformation; membrane engagement liberates the myristate and activates VPS34 for PI3P production [PMID:39913640]. VPS15 assembles into functionally distinct complexes: a Beclin1/UVRAG/BIF-1–containing PI3K-III sub-complex governing endocytic receptor degradation and cytokinesis [PMID:20643123], and a VPS34-independent complex with the golgin GM130 at the cis-Golgi that releases IFT20 for ciliary transport [PMID:27882921]. During autophagy initiation VPS15 is phosphorylated by ULK1/2 at multiple sites (including the major site serine 861), tuning VPS34 activity and autophagosome formation [PMID:34121209]. Across model organisms VPS15 is essential for autophagic clearance, lysosomal degradation, and tissue homeostasis: it is required downstream of autophagosome initiation for lysosomal fusion/degradation in muscle, where loss causes autophagic vacuolar myopathy [PMID:23630012], and a hypomorphic allele disrupts endosomal-lysosomal trafficking and neuronal migration via a Nischarin–Pak1 signaling axis, with a patient missense mutation (R998Q) selectively impairing the Golgi/ciliary function [PMID:27882921, PMID:29311744].","teleology":[{"year":1991,"claim":"Established that the protein-kinase activity of Vps15 is functionally essential, answering whether its kinase domain matters for vacuolar protein sorting.","evidence":"Site-directed mutagenesis of conserved kinase residues with in vivo phosphorylation and pulse-chase sorting assays in yeast","pmids":["1756716"],"confidence":"High","gaps":["Did not identify the binding partner or substrate of Vps15","Distinction between autophosphorylation and trans-phosphorylation unresolved"]},{"year":1993,"claim":"Identified VPS34 as the binding partner and defined VPS15's role as recruiter/activator, explaining how the kinase requirement translates into PI3-kinase function.","evidence":"Chemical cross-linking, native co-IP, subcellular fractionation and kinase-domain mutagenesis in yeast","pmids":["8387919"],"confidence":"High","gaps":["Structural basis of the Vps15-Vps34 interaction unknown","Mechanism of membrane recruitment not defined"]},{"year":1995,"claim":"Showed the functional Vps15-Vps34 complex is absolutely required for PI3P production and vacuolar delivery, linking complex integrity to lipid output.","evidence":"Temperature-conditional alleles, in vivo PtdIns(3)P measurement and dominant-negative genetics in yeast","pmids":["7721937"],"confidence":"High","gaps":["Did not resolve how PI3P drives downstream sorting machinery"]},{"year":1999,"claim":"Extended VPS15 function to selective pexophagy, indicating involvement at an early step of organelle-selective autophagy.","evidence":"Gene deletion in Pichia pastoris with peroxisomal marker assays and EM","pmids":["10591966"],"confidence":"Medium","gaps":["Single divergent yeast species","Molecular step within pexophagy not defined"]},{"year":2008,"claim":"Demonstrated VPS15 is essential for autophagy in a multicellular animal, establishing conservation of its autophagic role.","evidence":"Drosophila deletion mutant with GFP-Atg8a imaging, EM and biochemical fractionation","pmids":["18326940"],"confidence":"High","gaps":["Step in the autophagy pathway not pinpointed","Complex composition in flies not characterized"]},{"year":2009,"claim":"Solved the WD-domain structure and revealed a G-protein-coupled signaling role, defining a structural and signaling identity for VPS15 beyond VPS34.","evidence":"X-ray crystallography of the Vps15 WD domain plus Gpa1/Atg14 binding and signaling assays in yeast","pmids":["19445518"],"confidence":"High","gaps":["No independent replication of Gpa1 interaction in corpus","Relevance to mammalian VPS15 not established"]},{"year":2010,"claim":"Defined a distinct mammalian PI3K-III sub-complex (with Beclin1/UVRAG/BIF-1, lacking ATG14L) controlling receptor degradation and cytokinesis, showing complex-specific functions.","evidence":"siRNA depletion with high-content microscopy and midbody localization in mammalian cells","pmids":["20643123"],"confidence":"Medium","gaps":["No biochemical reconstitution of the sub-complex","Single lab"]},{"year":2013,"claim":"Placed VPS15/VPS34 downstream of autophagosome initiation at the lysosomal fusion/degradation step, refining its position within the autophagy pathway.","evidence":"Muscle-specific conditional Vps15 knockout mice with LC3/p62/LAMP2 readouts and rescue in Danon myoblasts","pmids":["23630012"],"confidence":"High","gaps":["Molecular basis of lysosomal fusion requirement not defined"]},{"year":2014,"claim":"Broadened VPS15 function to stress-induced and developmental autophagy and to secretory vesicle trafficking, indicating roles beyond canonical autophagy.","evidence":"Drosophila genetic mutants with autophagy markers, EM and salivary gland secretion assays","pmids":["25342466"],"confidence":"Medium","gaps":["Mechanism of secretory role not resolved","Single lab"]},{"year":2016,"claim":"Identified a VPS34-independent VPS15-GM130 Golgi complex required for ciliary cargo (IFT20) export, and linked a patient mutation to a separable function.","evidence":"Reciprocal co-IP, yeast complementation, patient fibroblast IFT20 localization and zebrafish cilia assays","pmids":["27882921"],"confidence":"High","gaps":["Stoichiometry and regulation of the GM130 complex unknown","How VPS15 partitions between VPS34 and GM130 complexes unclear"]},{"year":2018,"claim":"Connected VPS15-dependent trafficking to a Nischarin-Pak1 signaling axis controlling neuronal migration, revealing a developmental signaling consequence of VPS15 loss.","evidence":"ENU mutant and conditional KO mice with migration assays and epistasis, confirmed in human patients","pmids":["29311744"],"confidence":"High","gaps":["How trafficking defects raise Nischarin levels not mechanistically defined"]},{"year":2021,"claim":"Showed ULK1/2 directly phosphorylates VPS15 to tune VPS34 activity, establishing a regulatory input coupling autophagy initiation to lipid kinase output.","evidence":"Phosphoproteomics in Ulk1/2 DKO MEFs, in vitro VPS34 kinase assays with phosphosite mutants and VPS15 KO cells","pmids":["34121209"],"confidence":"High","gaps":["Conformational consequence of serine 861 phosphorylation unknown"]},{"year":2025,"claim":"Provided the structural mechanism of VPS34 autoinhibition and activation, explaining how the VPS15 pseudokinase domain controls lipid kinase output via GTP and myristate sequestration.","evidence":"Cryo-EM of the full PI3KC3-C1 complex with structural and functional analysis of pseudokinase-GTP and myristate release","pmids":["39913640"],"confidence":"High","gaps":["In vivo trigger and kinetics of membrane-induced myristate release not defined","How phosphorylation/partners feed into this switch unresolved"]},{"year":null,"claim":"How VPS15 is partitioned among its distinct complexes (VPS34/Beclin-UVRAG, GM130-Golgi) and how upstream signals select between trafficking, autophagy and ciliary functions remains open.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No quantitative model of complex partitioning","Mammalian relevance of WD-domain G-protein signaling untested","Direct VPS15-PDK1/PKC interaction not biochemically demonstrated"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,2]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,10]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[3]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[7]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[3,8]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,10]}],"pathway":[{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[5,6,9,12]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[1,4,14]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[1,7]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[4]}],"complexes":["PI3KC3 (class III PI3K) complex (VPS15-VPS34)","PI3K-III Beclin1/UVRAG/BIF-1 sub-complex","VPS15-GM130 cis-Golgi complex"],"partners":["VPS34","BECLIN1","UVRAG","BIF-1","GM130","ATG14","GPA1","ULK1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q99570","full_name":"Phosphoinositide 3-kinase regulatory subunit 4","aliases":["PI3-kinase p150 subunit","Phosphoinositide 3-kinase adaptor protein"],"length_aa":1358,"mass_kda":153.1,"function":"Regulatory subunit of the PI3K complex that mediates formation of phosphatidylinositol 3-phosphate; different complex forms are believed to play a role in multiple membrane trafficking pathways: PI3KC3-C1 is involved in initiation of autophagosomes and PI3KC3-C2 in maturation of autophagosomes and endocytosis. Involved in regulation of degradative endocytic trafficking and cytokinesis, probably in the context of PI3KC3-C2 (PubMed:20643123)","subcellular_location":"Late endosome; Cytoplasmic vesicle, autophagosome; Membrane","url":"https://www.uniprot.org/uniprotkb/Q99570/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/PIK3R4","classification":"Common Essential","n_dependent_lines":565,"n_total_lines":1208,"dependency_fraction":0.46771523178807944},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"ATG14","stoichiometry":10.0},{"gene":"BECN1","stoichiometry":10.0},{"gene":"PIK3C3","stoichiometry":10.0},{"gene":"CAPZB","stoichiometry":0.2},{"gene":"UVRAG","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/PIK3R4","total_profiled":1310},"omim":[{"mim_id":"616477","title":"NUCLEAR RECEPTOR-BINDING FACTOR 2; NRBF2","url":"https://www.omim.org/entry/616477"},{"mim_id":"613516","title":"RUN DOMAIN- AND CYSTEINE-RICH DOMAIN-CONTAINING BECLIN-1-INTERACTING PROTEIN; RUBCN","url":"https://www.omim.org/entry/613516"},{"mim_id":"613515","title":"AUTOPHAGY-RELATED 14; ATG14","url":"https://www.omim.org/entry/613515"},{"mim_id":"604378","title":"BECLIN 1; BECN1","url":"https://www.omim.org/entry/604378"},{"mim_id":"602610","title":"PHOSPHATIDYLINOSITOL 3-KINASE, REGULATORY SUBUNIT 4; PIK3R4","url":"https://www.omim.org/entry/602610"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Vesicles","reliability":"Approved"},{"location":"Microtubules","reliability":"Approved"},{"location":"Primary cilium","reliability":"Approved"},{"location":"Cytokinetic bridge","reliability":"Additional"},{"location":"Basal body","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PIK3R4"},"hgnc":{"alias_symbol":["VPS15","p150"],"prev_symbol":[]},"alphafold":{"accession":"Q99570","domains":[{"cath_id":"3.30.200.20","chopping":"2-106","consensus_level":"medium","plddt":74.6778,"start":2,"end":106},{"cath_id":"1.10.510.10","chopping":"112-206_236-318","consensus_level":"medium","plddt":88.5156,"start":112,"end":318},{"cath_id":"-","chopping":"739-803","consensus_level":"medium","plddt":82.0595,"start":739,"end":803},{"cath_id":"2.130.10.10","chopping":"986-1307_1329-1358","consensus_level":"medium","plddt":86.4889,"start":986,"end":1358}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q99570","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q99570-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q99570-F1-predicted_aligned_error_v6.png","plddt_mean":78.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PIK3R4","jax_strain_url":"https://www.jax.org/strain/search?query=PIK3R4"},"sequence":{"accession":"Q99570","fasta_url":"https://rest.uniprot.org/uniprotkb/Q99570.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q99570/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q99570"}},"corpus_meta":[{"pmid":"8387919","id":"PMC_8387919","title":"A membrane-associated complex containing the Vps15 protein kinase and the Vps34 PI 3-kinase is essential for protein sorting to the yeast lysosome-like vacuole.","date":"1993","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/8387919","citation_count":301,"is_preprint":false},{"pmid":"7721937","id":"PMC_7721937","title":"Vesicle-mediated protein transport: regulatory interactions between the Vps15 protein kinase and the Vps34 PtdIns 3-kinase essential for protein sorting to the vacuole in yeast.","date":"1995","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/7721937","citation_count":204,"is_preprint":false},{"pmid":"20643123","id":"PMC_20643123","title":"A phosphatidylinositol 3-kinase class III sub-complex containing VPS15, VPS34, Beclin 1, UVRAG and BIF-1 regulates cytokinesis and degradative endocytic traffic.","date":"2010","source":"Experimental cell 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neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/29311744","citation_count":39,"is_preprint":false},{"pmid":"10591966","id":"PMC_10591966","title":"A Pichia pastoris VPS15 homologue is required in selective peroxisome autophagy.","date":"1999","source":"Current genetics","url":"https://pubmed.ncbi.nlm.nih.gov/10591966","citation_count":37,"is_preprint":false},{"pmid":"17166233","id":"PMC_17166233","title":"ird1 is a Vps15 homologue important for antibacterial immune responses in Drosophila.","date":"2006","source":"Cellular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/17166233","citation_count":34,"is_preprint":false},{"pmid":"19445518","id":"PMC_19445518","title":"Structure and function of Vps15 in the endosomal G protein signaling pathway.","date":"2009","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/19445518","citation_count":29,"is_preprint":false},{"pmid":"39913640","id":"PMC_39913640","title":"Structural pathway for PI3-kinase regulation by VPS15 in autophagy.","date":"2025","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/39913640","citation_count":26,"is_preprint":false},{"pmid":"25342466","id":"PMC_25342466","title":"Vps15 is required for stress induced and developmentally triggered autophagy and salivary gland protein secretion in Drosophila.","date":"2014","source":"Cell death and differentiation","url":"https://pubmed.ncbi.nlm.nih.gov/25342466","citation_count":25,"is_preprint":false},{"pmid":"31356904","id":"PMC_31356904","title":"Vps15 is critical to mediate autophagy in AngII treated HUVECs probably by PDK1/PKC signaling pathway.","date":"2019","source":"Life sciences","url":"https://pubmed.ncbi.nlm.nih.gov/31356904","citation_count":8,"is_preprint":false},{"pmid":"36318587","id":"PMC_36318587","title":"A VPS15-like kinase regulates apicoplast biogenesis and autophagy by promoting PI3P generation in Toxoplasma gondii.","date":"2022","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/36318587","citation_count":5,"is_preprint":false},{"pmid":"32896555","id":"PMC_32896555","title":"Aspirin restores endothelial function by mitigating 17β-estradiol-induced α-SMA accumulation and autophagy inhibition via Vps15 scaffold regulation of Beclin-1 phosphorylation.","date":"2020","source":"Life sciences","url":"https://pubmed.ncbi.nlm.nih.gov/32896555","citation_count":4,"is_preprint":false},{"pmid":"40221008","id":"PMC_40221008","title":"Identification of NMT1/MA/VPS15 signal pathway as potential therapeutic target in rat cerebral ischemia injury.","date":"2025","source":"Experimental neurology","url":"https://pubmed.ncbi.nlm.nih.gov/40221008","citation_count":0,"is_preprint":false},{"pmid":"40537377","id":"PMC_40537377","title":"CryoEM provides detailed insights into how VPS15 regulates VPS34 activity.","date":"2025","source":"Trends in biochemical sciences","url":"https://pubmed.ncbi.nlm.nih.gov/40537377","citation_count":0,"is_preprint":false},{"pmid":"42189192","id":"PMC_42189192","title":"Genome-wide association study links COL6A6 and PIK3R4 to delayed cerebral ischaemia.","date":"2026","source":"Brain : a journal of neurology","url":"https://pubmed.ncbi.nlm.nih.gov/42189192","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.05.20.655092","title":"Class III PI3K is essential for Wingless secretion and Evi/Wls recycling in  <i>Drosophila</i>","date":"2025-05-21","source":"bioRxiv","url":"https://doi.org/10.1101/2025.05.20.655092","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":12185,"output_tokens":4128,"usd":0.049237,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":11949,"output_tokens":4242,"usd":0.082897,"stage2_stop_reason":"end_turn"},"total_usd":0.132134,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1993,\n      \"finding\": \"Vps15 protein kinase forms a hetero-oligomeric membrane-associated complex with the Vps34 PI 3-kinase; Vps15 is responsible for recruiting Vps34 to intracellular membranes, and an intact Vps15 kinase domain is required for activation of Vps34 PI 3-kinase activity.\",\n      \"method\": \"Chemical cross-linking, native immunoprecipitation, subcellular fractionation, sucrose density gradients, kinase domain mutagenesis, genetic suppression assay\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal methods (co-IP, fractionation, mutagenesis, genetic suppression) in a foundational study; independently replicated in subsequent work\",\n      \"pmids\": [\"8387919\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"Active Vps15p kinase domain is necessary for physical association with Vps34p and for recruitment of Vps34p to the membrane; catalytically inactive Vps15p mutants cannot associate with Vps34p. Functional Vps15p-Vps34p complex is absolutely required for efficient vacuolar protein delivery, as shown by temperature-conditional alleles causing loss of PI(3)P and missorting of soluble vacuolar proteins.\",\n      \"method\": \"Temperature-conditional allele analysis, in vivo PtdIns(3)P measurements, genetic dominant-negative analysis, mutagenesis of kinase/lipid kinase domains\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple allele types, PI3P quantification, and genetic epistasis; extends and replicates findings from PMID:8387919\",\n      \"pmids\": [\"7721937\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1991,\n      \"finding\": \"Alterations of conserved protein kinase residues in Vps15p biologically inactivate the protein, blocking vacuolar sorting of soluble hydrolases (CPY, PrA) but not the membrane protein alkaline phosphatase. C-terminal truncations of Vps15p abolish in vivo phosphorylation of Vps15p and cause a temperature-conditional vacuolar protein sorting defect, suggesting autophosphorylation is required for full activity.\",\n      \"method\": \"Site-directed mutagenesis of conserved kinase residues, in vivo 32P-phosphorylation assay, temperature-shift experiments, pulse-chase sorting assay\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — active-site mutagenesis with multiple in vivo functional readouts; foundational mechanistic study\",\n      \"pmids\": [\"1756716\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"The Vps15 WD-repeat domain forms a seven-bladed beta-propeller resembling a G-protein beta subunit and is sufficient to bind the G protein alpha subunit Gpa1 (preferentially GDP-bound) and Atg14. The kinase and intermediate domains of Vps15 additionally contribute to Gpa1 binding and are necessary for G protein signaling at endosomes.\",\n      \"method\": \"X-ray crystal structure of the Vps15 WD domain, binding assays (Gpa1-Vps15 interaction), domain deletion analysis, G protein signaling assays\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with functional domain dissection in a single study; no independent replication in corpus\",\n      \"pmids\": [\"19445518\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"A specific PI3K-III sub-complex containing VPS15, VPS34, Beclin 1, UVRAG and BIF-1 (but not ATG14L) regulates endocytic receptor degradation and cytokinesis in mammalian cells.\",\n      \"method\": \"siRNA depletion of individual subunits, high-content microscopy-based assays for receptor degradation and cytokinesis, midbody localization of UVRAG and BIF-1\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown with two independent cellular phenotypic readouts; single lab, no biochemical reconstitution of complex\",\n      \"pmids\": [\"20643123\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Drosophila Vps15 is required for starvation-induced autophagy in fat body and gut; loss of vps15 leads to accumulation of ubiquitin- and Ref(2)P/p62-positive, partially detergent-insoluble protein aggregates, establishing Vps15 as essential for autophagic clearance of protein aggregates in a multicellular organism.\",\n      \"method\": \"Drosophila deletion mutant, GFP-Atg8a fluorescence microscopy, electron microscopy, biochemical fractionation, Western blot, immuno-electron microscopy\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic loss-of-function with multiple orthogonal readouts (fluorescence, EM, biochemical fractionation) establishing pathway position\",\n      \"pmids\": [\"18326940\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Vps15 is required for lysosomal function in skeletal muscle; muscle-specific Vps15 knockout mice show accumulation of autophagosomes, p62, LC3, and Lamp2-positive vesicles, and develop autophagic vacuolar myopathy. Importantly, autophagosome formation (LC3-positive) and mTOR activation are maintained in Vps15-deficient cells, indicating Vps15/Vps34 is specifically required downstream (lysosomal fusion/degradation) rather than for autophagosome initiation per se.\",\n      \"method\": \"Conditional (muscle-specific) Vps15 knockout mouse, immunofluorescence, electron microscopy, LC3/p62/LAMP2 Western blot, creatine kinase assay, Vps15 rescue by overexpression in Danon disease myoblasts\",\n      \"journal\": \"EMBO molecular medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean conditional KO with multiple orthogonal phenotypic readouts and rescue experiment; defines specific step in autophagy pathway\",\n      \"pmids\": [\"23630012\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"VPS15 interacts with the golgin GM130 at the cis-Golgi, forming a complex devoid of VPS34, and is required for IFT20 release from the Golgi for transport to the primary cilium. A patient missense mutation VPS15-R998Q impairs this Golgi trafficking function without fully disrupting VPS34-dependent activities. VPS15 regulates primary cilium length in human fibroblasts.\",\n      \"method\": \"Missense mutation identification in ciliopathy patients, co-immunoprecipitation of VPS15 with GM130, subcellular localization (Golgi), humanized yeast complementation assay, IFT20 localization in patient fibroblasts, zebrafish cilia assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal co-IP, patient mutation functional validation in yeast and fibroblasts, zebrafish in vivo phenotype; multiple orthogonal methods\",\n      \"pmids\": [\"27882921\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"A hypomorphic Vps15 mutation in mice causes defects in endosomal-lysosomal trafficking and autophagy, resulting in upregulation of Nischarin, which inhibits Pak1 signaling, thereby disrupting neuronal migration and causing hippocampal pyramidal cell layer defects. Complete Vps15 ablation causes accumulation of autophagic substrates, apoptosis, and severe cortical atrophy.\",\n      \"method\": \"ENU-induced mouse mutant, conditional knockout, neuronal migration assays, Western blot for Nischarin and Pak1 phosphorylation, epistasis between Vps15, Nischarin, and Pak1 pathways\",\n      \"journal\": \"Nature neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic loss-of-function in mouse with epistasis establishing Vps15→Nischarin→Pak1 signaling axis; confirmed in human patients\",\n      \"pmids\": [\"29311744\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ULK1/2 kinases phosphorylate VPS15 at six sites (including serine 861 as the major site); mutation of these sites reduces VPS34 activity in vitro and impairs autophagosome formation in cells. VPS15 knockout also reveals ULK-dependent starvation-independent accumulation of ULK substrates and kinase activity-regulated recruitment of autophagy proteins to ubiquitin-positive structures.\",\n      \"method\": \"Unbiased phosphoproteomics in Ulk1/2 double-knockout MEFs, in vitro VPS34 kinase assay with VPS15 phosphosite mutants, autophagosome formation assays, VPS15 knockout cell lines\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — phosphoproteomics discovery combined with in vitro kinase reconstitution assay and cellular phenotypic validation; multiple orthogonal methods\",\n      \"pmids\": [\"34121209\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Cryo-EM structure of the PI3KC3-C1 complex reveals that the VPS15 pseudokinase domain binds GTP and sequesters its covalently-linked N-terminal myristate in the N-lobe, stabilizing the inactive conformation of VPS34. Upon membrane binding (activation), myristate is liberated, disrupting the inhibitory interaction and enabling VPS34 to catalyze PI3P production on membranes.\",\n      \"method\": \"Cryo-electron microscopy of full PI3KC3-C1 complex, structural analysis of pseudokinase-GTP interaction, myristate sequestration/release mechanism, functional validation of VPS34 activation\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — high-resolution cryo-EM structure with detailed mechanistic insight into activation pathway; single study but multiple structural and functional validations\",\n      \"pmids\": [\"39913640\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Pichia pastoris Vps15 (PpVPS15) is required at an early stage of selective peroxisome autophagy (pexophagy); deletion of PpVPS15 prevents vacuolar uptake of peroxisomes upon glucose or ethanol exposure.\",\n      \"method\": \"Gene deletion in Pichia pastoris, measurement of peroxisomal marker enzyme levels, electron microscopy of peroxisome uptake\",\n      \"journal\": \"Current genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — clean genetic deletion with EM and biochemical readouts but single study in a divergent yeast species (Pichia pastoris)\",\n      \"pmids\": [\"10591966\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Drosophila Vps15 is required for autophagy induced by multiple stresses (nutrient deprivation, hypoxia, oxidative stress) and for developmentally programmed autophagy in fat body, intestine, and salivary gland. Additionally, Vps15 is necessary for efficient protein secretion from salivary glands, demonstrating a role in secretory vesicle trafficking beyond autophagy.\",\n      \"method\": \"Drosophila vps15 genetic mutants, autophagy markers (Atg8, lysotracker), electron microscopy, salivary gland secretion assay\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic loss-of-function with multiple tissue/stress contexts and orthogonal readouts; single lab\",\n      \"pmids\": [\"25342466\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"VPS15 knockdown in HUVECs inhibits AngII-induced autophagy and reduces phosphorylation of PDK1 and PKC substrates, while re-expression of Vps15 rescues autophagy; PDK1 and PKC inhibitors phenocopy Vps15 knockdown, placing Vps15 upstream of a PDK1/PKC signaling axis in autophagy regulation.\",\n      \"method\": \"shRNA knockdown of Vps15, MDC staining, LC3-II/I Western blot, pharmacological inhibition of PDK1/PKC, rescue by Vps15 re-expression, flow cytometry for apoptosis\",\n      \"journal\": \"Life sciences\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single cell type, indirect pathway placement via inhibitor pharmacology without direct biochemical demonstration of VPS15-PDK1 interaction\",\n      \"pmids\": [\"31356904\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Loss of Vps15 (core PI3K-III subunit) in Drosophila wing imaginal discs selectively impairs an endocytosis-dependent pool of Wingless (Wg) secretion, causing apical accumulation of Wg in secreting cells, while a glypican-mediated Wg pool is unaffected. Evi/Wls cargo receptor undergoes proteasome-dependent degradation rather than accumulation in PI3K-III mutant cells.\",\n      \"method\": \"In vivo CRISPR-Cas9 kinome/phosphatome screen, endogenously fluorescently tagged Wg, super-resolution microscopy, ex vivo pharmacological treatments (proteasome inhibitor)\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo genetic screen with super-resolution imaging and pharmacological validation; preprint, not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2025.05.20.655092\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"VPS15 (PIK3R4) is a pseudokinase/regulatory subunit that forms the core of the class III PI3K complex with VPS34; its pseudokinase domain binds GTP and sequesters an N-terminal myristate to maintain the complex in an autoinhibited cytosolic state, and upon membrane engagement myristate release activates VPS34 to produce PI3P, which drives vesicular trafficking, vacuolar/lysosomal protein sorting, autophagosome formation, endosomal maturation, and cytokinesis; VPS15 also assembles VPS34-independent complexes (e.g., with GM130 at the Golgi for ciliary cargo sorting) and is phosphorylated by ULK1/2 to modulate VPS34 activity during autophagy initiation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PIK3R4 (VPS15) is the regulatory pseudokinase subunit at the core of the class III PI3-kinase complex, where it recruits and activates the VPS34 lipid kinase to drive PI3P-dependent vacuolar/lysosomal protein sorting, autophagy, endosomal trafficking, and cytokinesis [#0, #1]. It forms a hetero-oligomeric membrane-associated complex with VPS34, and its protein-kinase-domain integrity—originally characterized in yeast through active-site mutagenesis and conditional alleles—is required for both physical association with VPS34 and for activation of VPS34 lipid kinase activity, with loss of function causing depletion of PI3P and missorting of soluble vacuolar hydrolases [#0, #1, #2]. Structurally, the VPS15 WD-repeat domain folds into a seven-bladed beta-propeller that resembles a G-protein beta subunit [#3], while cryo-EM of the PI3KC3-C1 complex shows that the VPS15 pseudokinase domain binds GTP and sequesters its covalently linked N-terminal myristate to stabilize an autoinhibited VPS34 conformation; membrane engagement liberates the myristate and activates VPS34 for PI3P production [#10]. VPS15 assembles into functionally distinct complexes: a Beclin1/UVRAG/BIF-1–containing PI3K-III sub-complex governing endocytic receptor degradation and cytokinesis [#4], and a VPS34-independent complex with the golgin GM130 at the cis-Golgi that releases IFT20 for ciliary transport [#7]. During autophagy initiation VPS15 is phosphorylated by ULK1/2 at multiple sites (including the major site serine 861), tuning VPS34 activity and autophagosome formation [#9]. Across model organisms VPS15 is essential for autophagic clearance, lysosomal degradation, and tissue homeostasis: it is required downstream of autophagosome initiation for lysosomal fusion/degradation in muscle, where loss causes autophagic vacuolar myopathy [#6], and a hypomorphic allele disrupts endosomal-lysosomal trafficking and neuronal migration via a Nischarin–Pak1 signaling axis, with a patient missense mutation (R998Q) selectively impairing the Golgi/ciliary function [#7, #8].\",\n  \"teleology\": [\n    {\n      \"year\": 1991,\n      \"claim\": \"Established that the protein-kinase activity of Vps15 is functionally essential, answering whether its kinase domain matters for vacuolar protein sorting.\",\n      \"evidence\": \"Site-directed mutagenesis of conserved kinase residues with in vivo phosphorylation and pulse-chase sorting assays in yeast\",\n      \"pmids\": [\"1756716\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the binding partner or substrate of Vps15\", \"Distinction between autophosphorylation and trans-phosphorylation unresolved\"]\n    },\n    {\n      \"year\": 1993,\n      \"claim\": \"Identified VPS34 as the binding partner and defined VPS15's role as recruiter/activator, explaining how the kinase requirement translates into PI3-kinase function.\",\n      \"evidence\": \"Chemical cross-linking, native co-IP, subcellular fractionation and kinase-domain mutagenesis in yeast\",\n      \"pmids\": [\"8387919\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the Vps15-Vps34 interaction unknown\", \"Mechanism of membrane recruitment not defined\"]\n    },\n    {\n      \"year\": 1995,\n      \"claim\": \"Showed the functional Vps15-Vps34 complex is absolutely required for PI3P production and vacuolar delivery, linking complex integrity to lipid output.\",\n      \"evidence\": \"Temperature-conditional alleles, in vivo PtdIns(3)P measurement and dominant-negative genetics in yeast\",\n      \"pmids\": [\"7721937\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve how PI3P drives downstream sorting machinery\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Extended VPS15 function to selective pexophagy, indicating involvement at an early step of organelle-selective autophagy.\",\n      \"evidence\": \"Gene deletion in Pichia pastoris with peroxisomal marker assays and EM\",\n      \"pmids\": [\"10591966\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single divergent yeast species\", \"Molecular step within pexophagy not defined\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Demonstrated VPS15 is essential for autophagy in a multicellular animal, establishing conservation of its autophagic role.\",\n      \"evidence\": \"Drosophila deletion mutant with GFP-Atg8a imaging, EM and biochemical fractionation\",\n      \"pmids\": [\"18326940\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Step in the autophagy pathway not pinpointed\", \"Complex composition in flies not characterized\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Solved the WD-domain structure and revealed a G-protein-coupled signaling role, defining a structural and signaling identity for VPS15 beyond VPS34.\",\n      \"evidence\": \"X-ray crystallography of the Vps15 WD domain plus Gpa1/Atg14 binding and signaling assays in yeast\",\n      \"pmids\": [\"19445518\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No independent replication of Gpa1 interaction in corpus\", \"Relevance to mammalian VPS15 not established\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Defined a distinct mammalian PI3K-III sub-complex (with Beclin1/UVRAG/BIF-1, lacking ATG14L) controlling receptor degradation and cytokinesis, showing complex-specific functions.\",\n      \"evidence\": \"siRNA depletion with high-content microscopy and midbody localization in mammalian cells\",\n      \"pmids\": [\"20643123\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No biochemical reconstitution of the sub-complex\", \"Single lab\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Placed VPS15/VPS34 downstream of autophagosome initiation at the lysosomal fusion/degradation step, refining its position within the autophagy pathway.\",\n      \"evidence\": \"Muscle-specific conditional Vps15 knockout mice with LC3/p62/LAMP2 readouts and rescue in Danon myoblasts\",\n      \"pmids\": [\"23630012\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of lysosomal fusion requirement not defined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Broadened VPS15 function to stress-induced and developmental autophagy and to secretory vesicle trafficking, indicating roles beyond canonical autophagy.\",\n      \"evidence\": \"Drosophila genetic mutants with autophagy markers, EM and salivary gland secretion assays\",\n      \"pmids\": [\"25342466\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of secretory role not resolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identified a VPS34-independent VPS15-GM130 Golgi complex required for ciliary cargo (IFT20) export, and linked a patient mutation to a separable function.\",\n      \"evidence\": \"Reciprocal co-IP, yeast complementation, patient fibroblast IFT20 localization and zebrafish cilia assays\",\n      \"pmids\": [\"27882921\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and regulation of the GM130 complex unknown\", \"How VPS15 partitions between VPS34 and GM130 complexes unclear\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Connected VPS15-dependent trafficking to a Nischarin-Pak1 signaling axis controlling neuronal migration, revealing a developmental signaling consequence of VPS15 loss.\",\n      \"evidence\": \"ENU mutant and conditional KO mice with migration assays and epistasis, confirmed in human patients\",\n      \"pmids\": [\"29311744\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How trafficking defects raise Nischarin levels not mechanistically defined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Showed ULK1/2 directly phosphorylates VPS15 to tune VPS34 activity, establishing a regulatory input coupling autophagy initiation to lipid kinase output.\",\n      \"evidence\": \"Phosphoproteomics in Ulk1/2 DKO MEFs, in vitro VPS34 kinase assays with phosphosite mutants and VPS15 KO cells\",\n      \"pmids\": [\"34121209\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Conformational consequence of serine 861 phosphorylation unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Provided the structural mechanism of VPS34 autoinhibition and activation, explaining how the VPS15 pseudokinase domain controls lipid kinase output via GTP and myristate sequestration.\",\n      \"evidence\": \"Cryo-EM of the full PI3KC3-C1 complex with structural and functional analysis of pseudokinase-GTP and myristate release\",\n      \"pmids\": [\"39913640\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo trigger and kinetics of membrane-induced myristate release not defined\", \"How phosphorylation/partners feed into this switch unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How VPS15 is partitioned among its distinct complexes (VPS34/Beclin-UVRAG, GM130-Golgi) and how upstream signals select between trafficking, autophagy and ciliary functions remains open.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No quantitative model of complex partitioning\", \"Mammalian relevance of WD-domain G-protein signaling untested\", \"Direct VPS15-PDK1/PKC interaction not biochemically demonstrated\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 10]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [3, 8]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 10]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [5, 6, 9, 12]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [1, 4, 14]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [1, 7]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"complexes\": [\n      \"PI3KC3 (class III PI3K) complex (VPS15-VPS34)\",\n      \"PI3K-III Beclin1/UVRAG/BIF-1 sub-complex\",\n      \"VPS15-GM130 cis-Golgi complex\"\n    ],\n    \"partners\": [\n      \"VPS34\",\n      \"Beclin1\",\n      \"UVRAG\",\n      \"BIF-1\",\n      \"GM130\",\n      \"ATG14\",\n      \"Gpa1\",\n      \"ULK1\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}