{"gene":"PDZD11","run_date":"2026-06-10T05:19:53","timeline":{"discoveries":[{"year":2008,"finding":"PDZD11 (PISP/PDZK11) was identified as a novel effector in the insulin tyrosine phosphorylation cascade in brown adipocytes; a proteomic interaction screen identified the calcium-transporting ATPase SERCA2 as a binding partner of PDZD11, supporting a connection to calcium signaling.","method":"Quantitative phosphoproteomics (SILAC + phosphotyrosine immunoprecipitation + mass spectrometry); proteomic interaction screen","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — single proteomic screen identifying SERCA2 interaction, no functional follow-up on PDZD11 itself, single lab","pmids":["18268350"],"is_preprint":false},{"year":2016,"finding":"PDZD11 is recruited to adherens junctions by PLEKHA7: the WW domain of PLEKHA7 interacts directly with the N-terminal 44 amino acids of PDZD11 (shown by GST pulldown); PDZD11 in turn stabilizes nectin-1 and nectin-3 at junctions by directly binding their PDZ-binding motifs via its PDZ domain; loss of PDZD11 or PLEKHA7 leads to proteasome-mediated degradation of nectins and impaired early junction assembly.","method":"Yeast two-hybrid, mass spectrometry of immunoprecipitates, co-immunoprecipitation, GST pulldown, CRISPR/siRNA knockdown, immunofluorescence, calcium-switch junction assembly assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, GST pulldown, CRISPR KO with defined cellular phenotype, multiple orthogonal methods in a single rigorous study","pmids":["27044745"],"is_preprint":false},{"year":2010,"finding":"PDZD11 interacts with the sodium-dependent multivitamin transporter (hSMVT) via the PDZ-binding motif in the C-terminal tail of hSMVT; this interaction increases hSMVT membrane expression and biotin uptake, while siRNA knockdown of PDZD11 reduces hSMVT membrane levels and biotin uptake.","method":"Yeast two-hybrid screen, GST pulldown, mammalian two-hybrid luciferase assay, co-immunoprecipitation, confocal colocalization, [3H]biotin uptake assay, surface biotinylation, truncation analysis","journal":"American journal of physiology. Gastrointestinal and liver physiology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (Y2H, GST pulldown, Co-IP, functional uptake assay, surface biotinylation), single lab","pmids":["21183659"],"is_preprint":false},{"year":2018,"finding":"PDZD11 acts as a bridging factor enabling the WW domain of PLEKHA7 to bind the cytoplasmic C-terminus of Tspan33, thereby docking ADAM10 to cell-cell junctions; disruption of the PLEKHA7-PDZD11 complex inhibits ADAM10 junctional clustering and promotes toxin pore removal via actin- and macropinocytosis-dependent endocytosis, allowing cell survival.","method":"Co-immunoprecipitation, cell biological assays, CRISPR/siRNA loss-of-function, immunofluorescence, cytotoxicity assays","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal biochemical and cell biological evidence with defined phenotypic readout (toxin pore formation vs. survival), multiple methods across a single study","pmids":["30463011"],"is_preprint":false},{"year":2020,"finding":"Cooperative binding of the tandem WW domains (WW1 and WW2) of PLEKHA7 to a polyproline stretch in the N-terminal region of PDZD11 is required for their interaction; WW2 stabilizes WW1 and cooperatively promotes PDZD11 binding. PDZD11 binding induces a conformational rearrangement that enlarges a hydrophobic hot spot on WW1, enabling Trp-283 and Tyr-282 of Tspan33 to dock. Key residues Asp-30 (WW1) and His-75 (WW2), together with Thr-35 (WW1), form the binding pocket.","method":"Site-directed mutagenesis, GST pulldown, immunofluorescence, molecular modeling and docking","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — mutagenesis combined with GST pulldown and structural/docking modeling, multiple orthogonal methods in single study","pmids":["32371390"],"is_preprint":false},{"year":2021,"finding":"PLEKHA5 and PLEKHA6 interact with PDZD11 through their WW domains (binding to the PDZD11 N-terminus), analogously to PLEKHA7; these WW-PLEKHA–PDZD11 complexes are required for anterograde trafficking of the Menkes copper ATPase ATP7A to the cell periphery under elevated copper conditions, as shown by loss of peripheral ATP7A localization in CRISPR KO cells. Pull-down experiments showed that WW-PLEKHAs promote PDZD11 interaction with the C-terminus of ATP7A. WW-PLEKHAs and PDZD11 are required for maintaining low intracellular copper levels under copper challenge, but are not required for ATP7A Golgi retention in basal copper or copper-induced Golgi exit.","method":"Yeast two-hybrid, GST pulldown, CRISPR KO, immunofluorescence microscopy, copper measurements, metallothionein expression assay, cell viability assay","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — CRISPR KO with defined cellular phenotype, GST pulldown, functional copper homeostasis assays, multiple orthogonal methods","pmids":["34613798"],"is_preprint":false},{"year":2021,"finding":"The WW-mediated interaction between PLEKHA5 and PDZD11 is specifically required for their co-association with cytoplasmic microtubules, identifying a subcellular localization role for the PLEKHA5-PDZD11 interaction at microtubules.","method":"Expression of mutant and chimeric WW-PLEKHA proteins in cultured cells, immunofluorescence","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — localization experiments with chimeric/mutant proteins, single lab, no direct functional readout beyond localization","pmids":["34568338"],"is_preprint":false},{"year":2017,"finding":"In aortic endothelium-derived cells (meEC), PLEKHA7 and PDZD11 are significantly more associated with tight junction proteins cingulin and ZO-1 than in kidney epithelial cells, demonstrating cell-type-specific variation in the molecular architecture of the PDZD11-containing junctional complex.","method":"Proximity ligation assay, co-immunoprecipitation, immunofluorescence across multiple cell lines","journal":"Annals of the New York Academy of Sciences","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — proximity ligation and Co-IP across multiple cell types, single lab, descriptive mechanistic implication","pmids":["28617990"],"is_preprint":false},{"year":2022,"finding":"The PLEKHA7-PDZD11 complex regulates the localization of the plasma membrane calcium ATPase (PMCA): KO of PLEKHA7 or PDZD11 in epithelial cells causes increased lateral accumulation and ectopic apical localization of PMCA. PDZD11 interacts via its PDZ domain with the C-terminal PDZ-binding motif of PMCA b-isoforms; coexpression of PDZD11 reduces PMCA4x/b membrane accumulation and counteracts its calcium extrusion activity. KO of PDZD11 in endothelial or epithelial cells increases the rate of cytosolic calcium extrusion.","method":"CRISPR KO, immunofluorescence microscopy, surface biotinylation assay, cytosolic calcium transient measurements (functional assay), co-expression experiments in HeLa cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — CRISPR KO with functional calcium extrusion readout, surface biotinylation, and localization, multiple orthogonal methods in single lab","pmids":["35714771"],"is_preprint":false}],"current_model":"PDZD11 is a small PDZ domain-containing adaptor protein that is recruited to adherens junctions and lateral plasma membranes by WW domain-containing PLEKHA proteins (PLEKHA5, PLEKHA6, PLEKHA7), where its PDZ domain directly binds the C-terminal PDZ-binding motifs of transmembrane proteins including nectins, the sodium-dependent multivitamin transporter (hSMVT), the Menkes copper ATPase (ATP7A), and the plasma membrane calcium ATPase (PMCA), thereby regulating their membrane localization and function in junction assembly, copper homeostasis, biotin uptake, and calcium handling; additionally, PDZD11 acts as a bridge enabling PLEKHA7's WW1 domain to recruit Tspan33/ADAM10 to junctions through a cooperative, conformation-dependent mechanism."},"narrative":{"mechanistic_narrative":"PDZD11 is a small PDZ domain-containing adaptor that organizes the membrane localization and function of multiple transmembrane proteins at cell-cell junctions and the lateral plasma membrane [PMID:27044745, PMID:21183659]. Its central architecture couples two binding modes: a polyproline N-terminal region that is engaged by the WW domain(s) of PLEKHA-family scaffolds (PLEKHA7, PLEKHA5, PLEKHA6), and a PDZ domain that captures the C-terminal PDZ-binding motifs of client transmembrane proteins [PMID:27044745, PMID:32371390, PMID:34613798]. Through this bipartite recruitment, PLEKHA7 docks PDZD11 at adherens junctions where PDZD11 binds and stabilizes nectin-1 and nectin-3, preventing their proteasomal degradation and supporting early junction assembly [PMID:27044745]. The same PDZ-mediated capture targets functionally diverse clients: the sodium-dependent multivitamin transporter hSMVT, where PDZD11 promotes surface expression and biotin uptake [PMID:21183659]; the Menkes copper ATPase ATP7A, where WW-PLEKHA-PDZD11 complexes drive copper-induced anterograde trafficking to the cell periphery and maintain low intracellular copper [PMID:34613798]; and the plasma membrane calcium ATPase PMCA, whose lateral membrane distribution and calcium extrusion activity PDZD11 restrains [PMID:35714771]. Beyond positioning transporters, PDZD11 acts as a conformational bridge that licenses PLEKHA7's WW1 domain to recruit the Tspan33/ADAM10 sheddase complex to junctions, a mechanism that governs clustering of ADAM10 and cellular resistance to pore-forming toxins [PMID:30463011, PMID:32371390]. The molecular architecture of the PDZD11-containing complex varies by cell type, with stronger association to the tight-junction proteins cingulin and ZO-1 in endothelial than in epithelial cells [PMID:28617990].","teleology":[{"year":2008,"claim":"Establishing the first molecular handle on PDZD11, a proteomic screen placed it in calcium-signaling context by linking it to the SERCA2 calcium ATPase, raising the possibility that PDZD11 partners with calcium-handling machinery.","evidence":"SILAC phosphoproteomics and proteomic interaction screen in brown adipocytes","pmids":["18268350"],"confidence":"Medium","gaps":["Single proteomic screen with no functional follow-up on PDZD11","Direct binding and physiological consequence of the SERCA2 association not established"]},{"year":2010,"claim":"The first defined function of the PDZ domain showed PDZD11 binds the C-terminal PDZ motif of the transporter hSMVT to control its surface expression, establishing PDZD11 as a positive regulator of transmembrane transporter trafficking.","evidence":"Y2H, GST pulldown, Co-IP, surface biotinylation, and [3H]biotin uptake assays","pmids":["21183659"],"confidence":"High","gaps":["Did not identify how PDZD11 itself is recruited to membranes","Structural basis of PDZ-motif recognition not resolved"]},{"year":2016,"claim":"Identification of PLEKHA7's WW domain binding the PDZD11 N-terminus revealed the recruitment mechanism that positions PDZD11 at adherens junctions, where it stabilizes nectins against proteasomal degradation and supports junction assembly.","evidence":"Y2H, reciprocal Co-IP, GST pulldown, CRISPR/siRNA knockdown, and calcium-switch junction assembly assay","pmids":["27044745"],"confidence":"High","gaps":["Whether other PLEKHA paralogs recruit PDZD11 was not tested","Stoichiometry and structural detail of the WW-PDZD11 interface not defined"]},{"year":2017,"claim":"Comparison across cell types showed the PDZD11 junctional complex associates more with tight-junction proteins cingulin and ZO-1 in endothelial than epithelial cells, establishing that the molecular architecture around PDZD11 is cell-type dependent.","evidence":"Proximity ligation assay, Co-IP, and immunofluorescence across multiple cell lines","pmids":["28617990"],"confidence":"Medium","gaps":["Functional consequence of the differential tight-junction association unknown","Descriptive comparison without mechanistic dissection"]},{"year":2018,"claim":"PDZD11 was shown to function as a bridging factor enabling PLEKHA7's WW domain to dock Tspan33/ADAM10 at junctions, connecting the adaptor to sheddase positioning and toxin pore resistance.","evidence":"Co-IP, CRISPR/siRNA loss-of-function, immunofluorescence, and cytotoxicity assays","pmids":["30463011"],"confidence":"High","gaps":["Mechanism by which PDZD11 enables Tspan33 docking was not structurally explained at this stage","In vivo relevance of the pathway not addressed"]},{"year":2020,"claim":"Structural and mutagenesis analysis resolved the bridging mechanism: tandem WW1/WW2 domains bind a PDZD11 polyproline stretch cooperatively, and PDZD11 binding remodels WW1 to create the hydrophobic pocket that captures Tspan33, explaining the conformation-dependent recruitment.","evidence":"Site-directed mutagenesis, GST pulldown, immunofluorescence, and molecular modeling/docking","pmids":["32371390"],"confidence":"High","gaps":["Model based on docking rather than an experimental structure","Whether the same conformational mechanism applies to all WW-PLEKHA clients not tested"]},{"year":2021,"claim":"Demonstration that PLEKHA5 and PLEKHA6 also bind PDZD11 via their WW domains generalized the recruitment module beyond PLEKHA7 and revealed a role in copper-induced ATP7A trafficking and intracellular copper homeostasis.","evidence":"Y2H, GST pulldown, CRISPR KO, immunofluorescence, and copper/metallothionein functional assays","pmids":["34613798"],"confidence":"High","gaps":["Not required for ATP7A Golgi retention or copper-induced Golgi exit, leaving the precise trafficking step incompletely mapped","Whether different PLEKHA paralogs select distinct clients not resolved"]},{"year":2021,"claim":"A PLEKHA5-specific WW-PDZD11 interaction was found to target the complex to cytoplasmic microtubules, identifying a non-junctional subcellular pool of PDZD11.","evidence":"Expression of mutant and chimeric WW-PLEKHA proteins with immunofluorescence","pmids":["34568338"],"confidence":"Medium","gaps":["No functional readout beyond localization","Cargo or activity of the microtubule-associated pool unknown"]},{"year":2022,"claim":"PDZD11 was shown to bind PMCA b-isoforms via its PDZ domain and restrain their lateral membrane accumulation and calcium extrusion activity, extending PDZD11 control to plasma membrane calcium handling.","evidence":"CRISPR KO, surface biotinylation, cytosolic calcium transient measurements, and co-expression in HeLa cells","pmids":["35714771"],"confidence":"High","gaps":["Physiological context where PMCA regulation by PDZD11 matters not defined","Relationship between the 2008 SERCA2 link and PMCA regulation not reconciled"]},{"year":null,"claim":"It remains unknown how PDZD11 selects among its many transmembrane clients in a given cell and whether distinct WW-PLEKHA paralogs partition clients to specific membrane domains.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of a full WW-PLEKHA-PDZD11-client complex","Determinants of client selectivity and cell-type-specific output not established","In vivo / organismal phenotypes of PDZD11 loss not characterized in the corpus"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,2,3,5,8]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[2,5,8]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,2,8]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[6]}],"pathway":[{"term_id":"R-HSA-1500931","term_label":"Cell-Cell communication","supporting_discovery_ids":[1,7]},{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[2,5,8]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[3,5]}],"complexes":["PLEKHA7-PDZD11 junctional complex"],"partners":["PLEKHA7","PLEKHA5","PLEKHA6","SLC5A6","ATP7A","TSPAN33","ATP2B4","NECTIN1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q5EBL8","full_name":"PDZ domain-containing protein 11","aliases":["ATPase-interacting PDZ protein","Plasma membrane calcium ATPase-interacting single-PDZ protein","PMCA-interacting single-PDZ protein"],"length_aa":140,"mass_kda":16.1,"function":"Mediates docking of ADAM10 to zonula adherens by interacting with PLEKHA7 which is required for PLEKHA7 to interact with the ADAM10-binding protein TSPAN33","subcellular_location":"Cytoplasm; Cell junction, adherens junction; Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q5EBL8/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PDZD11","classification":"Not Classified","n_dependent_lines":4,"n_total_lines":1208,"dependency_fraction":0.0033112582781456954},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"MAP4","stoichiometry":4.0},{"gene":"POLR1C","stoichiometry":0.2},{"gene":"PSMB3","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/PDZD11","total_profiled":1310},"omim":[{"mim_id":"300632","title":"PDZ DOMAIN-CONTAINING 11; PDZD11","url":"https://www.omim.org/entry/300632"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PDZD11"},"hgnc":{"alias_symbol":[],"prev_symbol":["PDZK11"]},"alphafold":{"accession":"Q5EBL8","domains":[{"cath_id":"2.30.42.10","chopping":"43-140","consensus_level":"medium","plddt":86.7731,"start":43,"end":140}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q5EBL8","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q5EBL8-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q5EBL8-F1-predicted_aligned_error_v6.png","plddt_mean":82.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PDZD11","jax_strain_url":"https://www.jax.org/strain/search?query=PDZD11"},"sequence":{"accession":"Q5EBL8","fasta_url":"https://rest.uniprot.org/uniprotkb/Q5EBL8.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q5EBL8/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q5EBL8"}},"corpus_meta":[{"pmid":"18268350","id":"PMC_18268350","title":"Dissection of the insulin signaling pathway via quantitative phosphoproteomics.","date":"2008","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/18268350","citation_count":207,"is_preprint":false},{"pmid":"30463011","id":"PMC_30463011","title":"A Dock-and-Lock Mechanism Clusters ADAM10 at Cell-Cell Junctions to Promote α-Toxin Cytotoxicity.","date":"2018","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/30463011","citation_count":41,"is_preprint":false},{"pmid":"34613798","id":"PMC_34613798","title":"PLEKHA5, PLEKHA6, and PLEKHA7 bind to PDZD11 to target the Menkes ATPase ATP7A to the cell periphery and regulate copper homeostasis.","date":"2021","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/34613798","citation_count":36,"is_preprint":false},{"pmid":"27044745","id":"PMC_27044745","title":"PLEKHA7 Recruits PDZD11 to Adherens Junctions to Stabilize Nectins.","date":"2016","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/27044745","citation_count":27,"is_preprint":false},{"pmid":"27072621","id":"PMC_27072621","title":"PLEKHA7: Cytoskeletal adaptor protein at center stage in junctional organization and signaling.","date":"2016","source":"The international journal of biochemistry & cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/27072621","citation_count":26,"is_preprint":false},{"pmid":"21183659","id":"PMC_21183659","title":"Association of PDZ-containing protein PDZD11 with the human sodium-dependent multivitamin transporter.","date":"2010","source":"American journal of physiology. Gastrointestinal and liver physiology","url":"https://pubmed.ncbi.nlm.nih.gov/21183659","citation_count":22,"is_preprint":false},{"pmid":"28617990","id":"PMC_28617990","title":"Cell-specific diversity in the expression and organization of cytoplasmic plaque proteins of apical junctions.","date":"2017","source":"Annals of the New York Academy of Sciences","url":"https://pubmed.ncbi.nlm.nih.gov/28617990","citation_count":21,"is_preprint":false},{"pmid":"34568338","id":"PMC_34568338","title":"WW, PH and C-Terminal Domains Cooperate to Direct the Subcellular Localizations of PLEKHA5, PLEKHA6 and PLEKHA7.","date":"2021","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/34568338","citation_count":18,"is_preprint":false},{"pmid":"32371390","id":"PMC_32371390","title":"Cooperative binding of the tandem WW domains of PLEKHA7 to PDZD11 promotes conformation-dependent interaction with tetraspanin 33.","date":"2020","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/32371390","citation_count":9,"is_preprint":false},{"pmid":"35714771","id":"PMC_35714771","title":"The PLEKHA7-PDZD11 complex regulates the localization of the calcium pump PMCA and calcium handling in cultured cells.","date":"2022","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/35714771","citation_count":6,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7481,"output_tokens":2747,"usd":0.031824,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9957,"output_tokens":3513,"usd":0.068805,"stage2_stop_reason":"end_turn"},"total_usd":0.100629,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2008,\n      \"finding\": \"PDZD11 (PISP/PDZK11) was identified as a novel effector in the insulin tyrosine phosphorylation cascade in brown adipocytes; a proteomic interaction screen identified the calcium-transporting ATPase SERCA2 as a binding partner of PDZD11, supporting a connection to calcium signaling.\",\n      \"method\": \"Quantitative phosphoproteomics (SILAC + phosphotyrosine immunoprecipitation + mass spectrometry); proteomic interaction screen\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single proteomic screen identifying SERCA2 interaction, no functional follow-up on PDZD11 itself, single lab\",\n      \"pmids\": [\"18268350\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"PDZD11 is recruited to adherens junctions by PLEKHA7: the WW domain of PLEKHA7 interacts directly with the N-terminal 44 amino acids of PDZD11 (shown by GST pulldown); PDZD11 in turn stabilizes nectin-1 and nectin-3 at junctions by directly binding their PDZ-binding motifs via its PDZ domain; loss of PDZD11 or PLEKHA7 leads to proteasome-mediated degradation of nectins and impaired early junction assembly.\",\n      \"method\": \"Yeast two-hybrid, mass spectrometry of immunoprecipitates, co-immunoprecipitation, GST pulldown, CRISPR/siRNA knockdown, immunofluorescence, calcium-switch junction assembly assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, GST pulldown, CRISPR KO with defined cellular phenotype, multiple orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"27044745\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"PDZD11 interacts with the sodium-dependent multivitamin transporter (hSMVT) via the PDZ-binding motif in the C-terminal tail of hSMVT; this interaction increases hSMVT membrane expression and biotin uptake, while siRNA knockdown of PDZD11 reduces hSMVT membrane levels and biotin uptake.\",\n      \"method\": \"Yeast two-hybrid screen, GST pulldown, mammalian two-hybrid luciferase assay, co-immunoprecipitation, confocal colocalization, [3H]biotin uptake assay, surface biotinylation, truncation analysis\",\n      \"journal\": \"American journal of physiology. Gastrointestinal and liver physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (Y2H, GST pulldown, Co-IP, functional uptake assay, surface biotinylation), single lab\",\n      \"pmids\": [\"21183659\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"PDZD11 acts as a bridging factor enabling the WW domain of PLEKHA7 to bind the cytoplasmic C-terminus of Tspan33, thereby docking ADAM10 to cell-cell junctions; disruption of the PLEKHA7-PDZD11 complex inhibits ADAM10 junctional clustering and promotes toxin pore removal via actin- and macropinocytosis-dependent endocytosis, allowing cell survival.\",\n      \"method\": \"Co-immunoprecipitation, cell biological assays, CRISPR/siRNA loss-of-function, immunofluorescence, cytotoxicity assays\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal biochemical and cell biological evidence with defined phenotypic readout (toxin pore formation vs. survival), multiple methods across a single study\",\n      \"pmids\": [\"30463011\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Cooperative binding of the tandem WW domains (WW1 and WW2) of PLEKHA7 to a polyproline stretch in the N-terminal region of PDZD11 is required for their interaction; WW2 stabilizes WW1 and cooperatively promotes PDZD11 binding. PDZD11 binding induces a conformational rearrangement that enlarges a hydrophobic hot spot on WW1, enabling Trp-283 and Tyr-282 of Tspan33 to dock. Key residues Asp-30 (WW1) and His-75 (WW2), together with Thr-35 (WW1), form the binding pocket.\",\n      \"method\": \"Site-directed mutagenesis, GST pulldown, immunofluorescence, molecular modeling and docking\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis combined with GST pulldown and structural/docking modeling, multiple orthogonal methods in single study\",\n      \"pmids\": [\"32371390\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PLEKHA5 and PLEKHA6 interact with PDZD11 through their WW domains (binding to the PDZD11 N-terminus), analogously to PLEKHA7; these WW-PLEKHA–PDZD11 complexes are required for anterograde trafficking of the Menkes copper ATPase ATP7A to the cell periphery under elevated copper conditions, as shown by loss of peripheral ATP7A localization in CRISPR KO cells. Pull-down experiments showed that WW-PLEKHAs promote PDZD11 interaction with the C-terminus of ATP7A. WW-PLEKHAs and PDZD11 are required for maintaining low intracellular copper levels under copper challenge, but are not required for ATP7A Golgi retention in basal copper or copper-induced Golgi exit.\",\n      \"method\": \"Yeast two-hybrid, GST pulldown, CRISPR KO, immunofluorescence microscopy, copper measurements, metallothionein expression assay, cell viability assay\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — CRISPR KO with defined cellular phenotype, GST pulldown, functional copper homeostasis assays, multiple orthogonal methods\",\n      \"pmids\": [\"34613798\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The WW-mediated interaction between PLEKHA5 and PDZD11 is specifically required for their co-association with cytoplasmic microtubules, identifying a subcellular localization role for the PLEKHA5-PDZD11 interaction at microtubules.\",\n      \"method\": \"Expression of mutant and chimeric WW-PLEKHA proteins in cultured cells, immunofluorescence\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — localization experiments with chimeric/mutant proteins, single lab, no direct functional readout beyond localization\",\n      \"pmids\": [\"34568338\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In aortic endothelium-derived cells (meEC), PLEKHA7 and PDZD11 are significantly more associated with tight junction proteins cingulin and ZO-1 than in kidney epithelial cells, demonstrating cell-type-specific variation in the molecular architecture of the PDZD11-containing junctional complex.\",\n      \"method\": \"Proximity ligation assay, co-immunoprecipitation, immunofluorescence across multiple cell lines\",\n      \"journal\": \"Annals of the New York Academy of Sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — proximity ligation and Co-IP across multiple cell types, single lab, descriptive mechanistic implication\",\n      \"pmids\": [\"28617990\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The PLEKHA7-PDZD11 complex regulates the localization of the plasma membrane calcium ATPase (PMCA): KO of PLEKHA7 or PDZD11 in epithelial cells causes increased lateral accumulation and ectopic apical localization of PMCA. PDZD11 interacts via its PDZ domain with the C-terminal PDZ-binding motif of PMCA b-isoforms; coexpression of PDZD11 reduces PMCA4x/b membrane accumulation and counteracts its calcium extrusion activity. KO of PDZD11 in endothelial or epithelial cells increases the rate of cytosolic calcium extrusion.\",\n      \"method\": \"CRISPR KO, immunofluorescence microscopy, surface biotinylation assay, cytosolic calcium transient measurements (functional assay), co-expression experiments in HeLa cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR KO with functional calcium extrusion readout, surface biotinylation, and localization, multiple orthogonal methods in single lab\",\n      \"pmids\": [\"35714771\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PDZD11 is a small PDZ domain-containing adaptor protein that is recruited to adherens junctions and lateral plasma membranes by WW domain-containing PLEKHA proteins (PLEKHA5, PLEKHA6, PLEKHA7), where its PDZ domain directly binds the C-terminal PDZ-binding motifs of transmembrane proteins including nectins, the sodium-dependent multivitamin transporter (hSMVT), the Menkes copper ATPase (ATP7A), and the plasma membrane calcium ATPase (PMCA), thereby regulating their membrane localization and function in junction assembly, copper homeostasis, biotin uptake, and calcium handling; additionally, PDZD11 acts as a bridge enabling PLEKHA7's WW1 domain to recruit Tspan33/ADAM10 to junctions through a cooperative, conformation-dependent mechanism.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PDZD11 is a small PDZ domain-containing adaptor that organizes the membrane localization and function of multiple transmembrane proteins at cell-cell junctions and the lateral plasma membrane [#1, #2]. Its central architecture couples two binding modes: a polyproline N-terminal region that is engaged by the WW domain(s) of PLEKHA-family scaffolds (PLEKHA7, PLEKHA5, PLEKHA6), and a PDZ domain that captures the C-terminal PDZ-binding motifs of client transmembrane proteins [#1, #4, #5]. Through this bipartite recruitment, PLEKHA7 docks PDZD11 at adherens junctions where PDZD11 binds and stabilizes nectin-1 and nectin-3, preventing their proteasomal degradation and supporting early junction assembly [#1]. The same PDZ-mediated capture targets functionally diverse clients: the sodium-dependent multivitamin transporter hSMVT, where PDZD11 promotes surface expression and biotin uptake [#2]; the Menkes copper ATPase ATP7A, where WW-PLEKHA-PDZD11 complexes drive copper-induced anterograde trafficking to the cell periphery and maintain low intracellular copper [#5]; and the plasma membrane calcium ATPase PMCA, whose lateral membrane distribution and calcium extrusion activity PDZD11 restrains [#8]. Beyond positioning transporters, PDZD11 acts as a conformational bridge that licenses PLEKHA7's WW1 domain to recruit the Tspan33/ADAM10 sheddase complex to junctions, a mechanism that governs clustering of ADAM10 and cellular resistance to pore-forming toxins [#3, #4]. The molecular architecture of the PDZD11-containing complex varies by cell type, with stronger association to the tight-junction proteins cingulin and ZO-1 in endothelial than in epithelial cells [#7].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Establishing the first molecular handle on PDZD11, a proteomic screen placed it in calcium-signaling context by linking it to the SERCA2 calcium ATPase, raising the possibility that PDZD11 partners with calcium-handling machinery.\",\n      \"evidence\": \"SILAC phosphoproteomics and proteomic interaction screen in brown adipocytes\",\n      \"pmids\": [\"18268350\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single proteomic screen with no functional follow-up on PDZD11\", \"Direct binding and physiological consequence of the SERCA2 association not established\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"The first defined function of the PDZ domain showed PDZD11 binds the C-terminal PDZ motif of the transporter hSMVT to control its surface expression, establishing PDZD11 as a positive regulator of transmembrane transporter trafficking.\",\n      \"evidence\": \"Y2H, GST pulldown, Co-IP, surface biotinylation, and [3H]biotin uptake assays\",\n      \"pmids\": [\"21183659\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify how PDZD11 itself is recruited to membranes\", \"Structural basis of PDZ-motif recognition not resolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identification of PLEKHA7's WW domain binding the PDZD11 N-terminus revealed the recruitment mechanism that positions PDZD11 at adherens junctions, where it stabilizes nectins against proteasomal degradation and supports junction assembly.\",\n      \"evidence\": \"Y2H, reciprocal Co-IP, GST pulldown, CRISPR/siRNA knockdown, and calcium-switch junction assembly assay\",\n      \"pmids\": [\"27044745\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether other PLEKHA paralogs recruit PDZD11 was not tested\", \"Stoichiometry and structural detail of the WW-PDZD11 interface not defined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Comparison across cell types showed the PDZD11 junctional complex associates more with tight-junction proteins cingulin and ZO-1 in endothelial than epithelial cells, establishing that the molecular architecture around PDZD11 is cell-type dependent.\",\n      \"evidence\": \"Proximity ligation assay, Co-IP, and immunofluorescence across multiple cell lines\",\n      \"pmids\": [\"28617990\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of the differential tight-junction association unknown\", \"Descriptive comparison without mechanistic dissection\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"PDZD11 was shown to function as a bridging factor enabling PLEKHA7's WW domain to dock Tspan33/ADAM10 at junctions, connecting the adaptor to sheddase positioning and toxin pore resistance.\",\n      \"evidence\": \"Co-IP, CRISPR/siRNA loss-of-function, immunofluorescence, and cytotoxicity assays\",\n      \"pmids\": [\"30463011\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which PDZD11 enables Tspan33 docking was not structurally explained at this stage\", \"In vivo relevance of the pathway not addressed\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Structural and mutagenesis analysis resolved the bridging mechanism: tandem WW1/WW2 domains bind a PDZD11 polyproline stretch cooperatively, and PDZD11 binding remodels WW1 to create the hydrophobic pocket that captures Tspan33, explaining the conformation-dependent recruitment.\",\n      \"evidence\": \"Site-directed mutagenesis, GST pulldown, immunofluorescence, and molecular modeling/docking\",\n      \"pmids\": [\"32371390\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Model based on docking rather than an experimental structure\", \"Whether the same conformational mechanism applies to all WW-PLEKHA clients not tested\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Demonstration that PLEKHA5 and PLEKHA6 also bind PDZD11 via their WW domains generalized the recruitment module beyond PLEKHA7 and revealed a role in copper-induced ATP7A trafficking and intracellular copper homeostasis.\",\n      \"evidence\": \"Y2H, GST pulldown, CRISPR KO, immunofluorescence, and copper/metallothionein functional assays\",\n      \"pmids\": [\"34613798\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Not required for ATP7A Golgi retention or copper-induced Golgi exit, leaving the precise trafficking step incompletely mapped\", \"Whether different PLEKHA paralogs select distinct clients not resolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"A PLEKHA5-specific WW-PDZD11 interaction was found to target the complex to cytoplasmic microtubules, identifying a non-junctional subcellular pool of PDZD11.\",\n      \"evidence\": \"Expression of mutant and chimeric WW-PLEKHA proteins with immunofluorescence\",\n      \"pmids\": [\"34568338\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No functional readout beyond localization\", \"Cargo or activity of the microtubule-associated pool unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"PDZD11 was shown to bind PMCA b-isoforms via its PDZ domain and restrain their lateral membrane accumulation and calcium extrusion activity, extending PDZD11 control to plasma membrane calcium handling.\",\n      \"evidence\": \"CRISPR KO, surface biotinylation, cytosolic calcium transient measurements, and co-expression in HeLa cells\",\n      \"pmids\": [\"35714771\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological context where PMCA regulation by PDZD11 matters not defined\", \"Relationship between the 2008 SERCA2 link and PMCA regulation not reconciled\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unknown how PDZD11 selects among its many transmembrane clients in a given cell and whether distinct WW-PLEKHA paralogs partition clients to specific membrane domains.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structure of a full WW-PLEKHA-PDZD11-client complex\", \"Determinants of client selectivity and cell-type-specific output not established\", \"In vivo / organismal phenotypes of PDZD11 loss not characterized in the corpus\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 2, 3, 5, 8]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [2, 5, 8]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 2, 8]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1500931\", \"supporting_discovery_ids\": [1, 7]},\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [2, 5, 8]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [3, 5]}\n    ],\n    \"complexes\": [\"PLEKHA7-PDZD11 junctional complex\"],\n    \"partners\": [\"PLEKHA7\", \"PLEKHA5\", \"PLEKHA6\", \"SLC5A6\", \"ATP7A\", \"Tspan33\", \"ATP2B4\", \"NECTIN1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":6,"faith_total":6,"faith_pct":100.0}}