{"gene":"CLCN5","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":1994,"finding":"CLCN5 (initially termed hCIC-K2) was identified as a novel member of the CLC family of voltage-gated chloride channels, expressed predominantly in the kidney, with its genomic region completely deleted in Dent's disease patients, establishing it as the candidate disease gene.","method":"Positional cloning using YAC screening of kidney cDNA library; evolutionary conservation analysis; deletion mapping","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — positional cloning with genomic deletion confirmation, replicated by subsequent studies identifying loss-of-function mutations","pmids":["7874126"],"is_preprint":false},{"year":1995,"finding":"Heterologous expression of rat CLC-5 in Xenopus oocytes elicits novel, strongly outwardly rectifying anion currents with conductivity sequence NO3- > Cl- > Br- > I- >> glutamate-, establishing direct chloride channel activity; cAMP had no effect on these currents.","method":"Xenopus oocyte expression system with two-electrode voltage clamp; pharmacological manipulation of cAMP","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct electrophysiological reconstitution in oocytes, replicated across multiple subsequent studies","pmids":["8537381"],"is_preprint":false},{"year":1998,"finding":"ClC-5 colocalizes with the vacuolar H+-ATPase (proton pump) and with internalized proteins in endocytotically active renal proximal tubule cells and alpha-intercalated cells, and in transfected cells colocalizes with endocytosed alpha2-macroglobulin and enlarges rab5-Q79L early endosomes, suggesting ClC-5 resides in early endosomes and provides an electrical shunt for endosomal acidification.","method":"Immunofluorescence colocalization; cotransfection with GTPase-deficient rab5 mutant; endosome tracking with labeled ligands","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal localization methods, replicated in multiple subsequent studies across labs","pmids":["9653142"],"is_preprint":false},{"year":1999,"finding":"Active-site mutagenesis of ClC-5 demonstrated that point mutations at the end of transmembrane domain D2 (S168T) change ion selectivity, and a mutation at D3 (E211A) changes voltage dependence and ion selectivity, directly establishing that ClC-4 and ClC-5 mediate plasma membrane currents and that these residues contribute to the ion permeation pathway.","method":"Site-directed mutagenesis; two-electrode voltage clamp in Xenopus oocytes and patch-clamp in HEK293 cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstitution with mutagenesis in two heterologous expression systems, multiple mutants tested","pmids":["9873029"],"is_preprint":false},{"year":1999,"finding":"Human CLC-5 is co-distributed with Rab4 (a recycling early endosome marker) in subcellular fractions of human kidney cortex, and colocalizes with albumin-containing endocytic vesicles in opossum kidney proximal tubule cells, placing CLC-5 in the receptor-mediated endocytic pathway.","method":"Subcellular fractionation; immunoblotting; confocal immunofluorescence microscopy with albumin endocytosis tracking","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (fractionation + confocal), human tissue validated","pmids":["9931332"],"is_preprint":false},{"year":2000,"finding":"Disruption of the mouse clcn5 gene causes proteinuria by strongly reducing apical proximal tubular endocytosis (both receptor-mediated and fluid-phase), establishing ClC-5 as essential for renal endocytosis; additionally, internalization of apical transporters NaPi-2 and NHE3 is slowed.","method":"Clcn5 knockout mouse; endocytosis assays with labeled tracers; immunohistochemistry and subcellular fractionation of NaPi-2 and NHE3","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO mouse with specific endocytic phenotype, replicated by independent groups","pmids":["11099045"],"is_preprint":false},{"year":2000,"finding":"A carboxyl-terminal PY-like motif in ClC-5 mediates its internalization from the plasma membrane via interaction with WW domain-containing ubiquitin-protein ligase WWP2; mutation of this motif increases surface expression and currents ~2-fold, and dominant-negative WWP2 increases surface ClC-5 only when the PY motif is intact.","method":"Site-directed mutagenesis of PY motif; dominant-negative expression of WWP2; rab5 overexpression/dominant-negative studies; electrophysiology in Xenopus oocytes","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — mutagenesis combined with dominant-negative functional assays and multiple rab5 constructs in a single study","pmids":["11116157"],"is_preprint":false},{"year":2002,"finding":"Endosomes from Clcn5 knockout mice are acidified at a significantly lower rate than wild-type endosomes, confirming that ClC-5 provides an electrical shunt for efficient vacuolar H+-ATPase operation; defective endocytosis leads to elevated luminal PTH, causing increased endocytosis of NaPi phosphate transporter and phosphaturia.","method":"Clcn5 KO mouse; endosomal acidification assay; hormone level measurements; immunohistochemistry of NaPi","journal":"Pflugers Archiv : European journal of physiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO mouse with direct endosomal pH measurement, mechanistic cascade validated","pmids":["12548389"],"is_preprint":false},{"year":2003,"finding":"Loss of CLC-5 in Dent's disease patients is associated with inversion of H+-ATPase polarity in proximal tubule cells (basolateral rather than apical) without ultrastructural changes, demonstrating that CLC-5 is required to maintain proper H+-ATPase polarity.","method":"Immunohistochemistry of renal biopsies from Dent's disease patients; confocal microscopy","journal":"Kidney international","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — single lab, human biopsy immunohistochemistry, no functional rescue experiment","pmids":["12631345"],"is_preprint":false},{"year":2004,"finding":"Nedd4-2 interacts with ClC-5 via a direct binding of the C-terminus of ClC-5 to Nedd4-2; Nedd4-2 decreases cell surface expression of ClC-5 in Xenopus oocytes; albumin stimulates ubiquitination of ClC-5 and increases its surface expression; knockdown of Nedd4-2 by siRNA reduces albumin uptake in proximal tubule cells.","method":"In vivo co-immunoprecipitation; GST pull-down; Xenopus oocyte electrophysiology; siRNA knockdown; albumin endocytosis assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal pull-down plus siRNA functional rescue, multiple orthogonal methods in single lab","pmids":["15489223"],"is_preprint":false},{"year":2005,"finding":"Adenoviral re-expression of wild-type ClC-5 rescues receptor-mediated endocytosis in ClC-5 KO proximal tubule cells, whereas disease-causing mutants (W22G, S520P, R704X) do not rescue endocytosis; S520P and R704X are not internalized normally, suggesting defective targeting/trafficking underlies Dent's disease in these cases.","method":"Adenoviral transduction of KO primary proximal tubule cells; endocytosis assay; surface biotinylation; electrophysiology","journal":"American journal of physiology. Renal physiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — functional rescue in KO cells with WT and mutant constructs, multiple orthogonal assays","pmids":["15942052"],"is_preprint":false},{"year":2005,"finding":"ClC-5 has an internal C-terminal binding site that directly interacts with the PDZ2 domain of NHERF2 (but not NHERF1); silencing NHERF2 reduces cell-surface ClC-5 and albumin uptake, whereas silencing NHERF1 increases ClC-5 surface levels and albumin endocytosis.","method":"Co-immunoprecipitation from OK cell lysate; GST fusion protein pull-down; siRNA knockdown; surface biotinylation; albumin endocytosis assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — direct interaction mapping with GST pull-down plus siRNA functional data, single lab with multiple methods","pmids":["16601121"],"is_preprint":false},{"year":2006,"finding":"The C-terminus of ClC-5 (containing CBS domains) directly binds ATP with low millimolar affinity; ATP and AMP binding induces no change in secondary structure but increases thermal stability of the C-terminal domain.","method":"Radiolabeled ATP binding assay; circular dichroism (CD) spectroscopy; thermal stability measurements with purified recombinant C-terminal domain","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro biochemical reconstitution with purified domain, multiple biophysical readouts in single study","pmids":["16686597"],"is_preprint":false},{"year":2008,"finding":"CLC-5 mutations causing Dent's disease fall into three functional classes: Class 1 mutations cause ER retention and degradation; Class 2 mutations allow normal trafficking but abolish endosomal acidification; Class 3 mutations alter endosomal distribution but preserve acidification. Molecular modeling showed each class maps to discrete structural regions.","method":"Electrophysiology; subcellular localization by confocal microscopy; endosomal acidification assay; 3D homology modeling of seven missense mutants","journal":"American journal of physiology. Renal physiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — multiple orthogonal functional and cell-biological methods on multiple disease mutants, structural modeling in single study","pmids":["19019917"],"is_preprint":false},{"year":2009,"finding":"CLC-5 interacts with the kinesin motor protein KIF3B via the C-terminus of CLC-5 and the coiled-coil/globular domains of KIF3B; KIF3B overexpression increases and KIF3B siRNA knockdown decreases CLC-5 surface expression and albumin/transferrin endocytosis; CLC-5-containing vesicles move along KIF3B microtubules in live kidney cells.","method":"Yeast two-hybrid; GST pull-down; co-immunoprecipitation (including endogenous); confocal live-cell imaging; siRNA knockdown; endocytosis assay","journal":"American journal of physiology. Renal physiology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP plus yeast two-hybrid plus live imaging plus siRNA functional assay, multiple orthogonal methods single lab","pmids":["19940036"],"is_preprint":false},{"year":2010,"finding":"CLC-5 directly acidifies endosomes by exchanging endosomal Cl- for H+ from the cytoplasm (acting as a Cl-/H+ exchanger), providing a bafilomycin-insensitive component of endosomal acidification; mutations that remove H+ transport (E268A, E211A) abolish this additional acidification. siRNA knockdown of endogenous CLC-5 in proximal tubule cells nearly fully ablated bafilomycin-insensitive acidification.","method":"Whole-cell patch clamp; pH-sensitive fluorescent protein targeted to endosomes; site-directed mutagenesis (E268A, E211A); siRNA knockdown; bafilomycin inhibition","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — multiple mutagenesis approaches combined with direct endosomal pH measurement and siRNA validation in single rigorous study","pmids":["20421284"],"is_preprint":false},{"year":2010,"finding":"ClC-5 PY-motif-dependent ubiquitylation is dispensable for proximal tubular endocytosis in vivo: knock-in mice with a destroyed PY-motif show neither proteinuria nor hyperphosphaturia, and receptor-mediated and fluid-phase endocytosis are normal, contradicting results from heterologous expression systems.","method":"PY-motif knock-in mouse; urine protein analysis; endocytosis assays; megalin and NaPi-2a localization by immunohistochemistry","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean knock-in mouse model with definitive negative in vivo phenotype, rigorous controls, directly contradicts heterologous expression studies","pmids":["20351103"],"is_preprint":false},{"year":2010,"finding":"CLC-5 voltage sensing is an intrinsic property of the protein; permeant anions (particularly Cl-) modulate a voltage-dependent transition to an activated state from which Cl-/H+ exchange occurs. Intracellular Cl- shifts the charge-voltage relationship while lowering intracellular pH does not shift voltage dependence of gating currents.","method":"Whole-cell patch clamp of E268A permeation-deficient mutant; gating current recordings; ion substitution experiments","journal":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct gating current measurements with structure-function mutagenesis in single rigorous study","pmids":["20501796"],"is_preprint":false},{"year":2010,"finding":"Extracellular protons inhibit CLC-5 by binding to a single site at the extracellular gating glutamate E211, located halfway through the transmembrane electric field, driving the transport cycle in a less permissive direction rather than by reducing driving force.","method":"Electrophysiology with varying extracellular pH; SCN- uncoupling experiments to separate H+ and Cl- transport; mechanistic transport cycle modeling","journal":"The Journal of general physiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — rigorous biophysical dissection using SCN- uncoupling plus pH manipulation, identifying a specific gating mechanism","pmids":["20513761"],"is_preprint":false},{"year":2010,"finding":"ATP binding induces a conformational change (clamp-like closure) in the isolated C-terminal region of ClC-5, as shown by small-angle X-ray scattering; this conformational compaction promotes biosynthetic maturation and ER exit of full-length ClC-5. Disruption of the ATP-binding site (Y617A) impairs processing and ER trafficking.","method":"Small-angle X-ray scattering (SAXS); limited proteolysis; site-directed mutagenesis (Y617A); trafficking assay in fibroblasts and proximal tubule cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — structural SAXS combined with mutagenesis and cell-based trafficking validation in single study","pmids":["21173145"],"is_preprint":false},{"year":2011,"finding":"ClC-5 is required for exocytic trafficking of NHE3: ClC-5 knockdown reduces basal and dexamethasone-stimulated NHE3 exocytosis (but not endocytosis) in opossum kidney cells, and NHE3 activity is reduced in proximal tubules of Clcn5 KO mice.","method":"shRNA knockdown in OK cells; surface biotinylation exocytosis/endocytosis assays; two-photon microscopy of NHE3 activity in Clcn5 KO mice; single tubule perfusion","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — siRNA functional data in cell line confirmed with Clcn5 KO mouse, two orthogonal approaches","pmids":["21561868"],"is_preprint":false},{"year":2012,"finding":"ClC-5 and megalin interact via their C-termini, and this interaction is scaffolded by NHERF2: GST pull-down and co-immunoprecipitation in rat kidney lysate demonstrated the ClC-5/megalin complex; silencing NHERF2 disrupts the megalin/ClC-5 interaction. Fusion protein reconstitution demonstrated a three-protein complex of ClC-5, megalin, and NHERF2.","method":"GST pull-down; co-immunoprecipitation from rat kidney lysate; siRNA knockdown of NHERF2; fusion protein reconstitution","journal":"The international journal of biochemistry & cell biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal pull-down plus endogenous co-IP plus in vitro reconstitution, single lab multiple methods","pmids":["22349218"],"is_preprint":false},{"year":2012,"finding":"The proton glutamate E268 of ClC-5 mediates protonation of gating glutamate E211: internal protons increase transport probability of ClC-5 via protonation of E211 at the central anion-binding site, and this effect requires E268. Sulfhydryl modification of E268C mutant confirmed the charge-dependent mechanism.","method":"Site-directed mutagenesis (E268H, E268C, E211C, S168P); gating charge measurements; site-directed sulfhydryl modification; electrophysiology","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — rigorous structure-function mutagenesis with multiple complementary mutants and chemical modification in single study","pmids":["22267722"],"is_preprint":false},{"year":2013,"finding":"Disease-causing ClC-5 mutants C221R (membrane domain) and R718X (C-terminal truncation) are misfolded: limited proteolysis shows enhanced protease susceptibility relative to wild-type. C221R disrupts intramolecular interactions affecting the N-terminal cytosolic region; R718X perturbs both C-terminal and membrane domains. Both misfolded mutants are polyubiquitinated and degraded by the proteasome in renal proximal tubule cells.","method":"Limited proteolysis; proteasome inhibition assay; polyubiquitination immunoprecipitation in OK cells; protein stability assays","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct biophysical evidence for misfolding combined with cell-based degradation pathway identification in single study","pmids":["23566014"],"is_preprint":false},{"year":2016,"finding":"The gating glutamate E211Q mutation converts ClC-5 from a 2Cl-/H+ exchanger into a pure Cl- channel, which still causes Dent's disease in humans via insufficient V-ATPase activation; both E211A and E211Q stimulate endosomal acidification and V-ATPase activation but less effectively than WT ClC-5, demonstrating functional coupling between V-ATPase and CLC-5.","method":"Xenopus oocyte electrophysiology; surface pH measurement; V-ATPase activation assay in HEK293 cells and isolated mouse proximal tubules; gene silencing","journal":"Pflugers Archiv : European journal of physiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — electrophysiological reconstitution plus direct V-ATPase functional coupling demonstrated in cells and native tissue","pmids":["27044412"],"is_preprint":false},{"year":2018,"finding":"A novel gating glutamate mutation p.Glu211Gly converts ClC-5 to a Cl- channel (abolishes outward rectification, pH sensitivity, and Cl-/H+ exchange) but does not impair N-glycosylation, plasma membrane localization, or endosomal localization, and does not significantly alter luminal endosomal pH in HEK293T cells, demonstrating that impaired endosomal acidification is not the sole mechanism of Dent's disease.","method":"Xenopus oocyte electrophysiology; HEK293T cell expression; N-glycosylation analysis; subcellular localization; pHluorin2 endosomal pH measurement","journal":"Human mutation","confidence":"High","confidence_rationale":"Tier 1 / Moderate — multiple functional and cell-biological assays with direct endosomal pH measurement in single study","pmids":["29791050"],"is_preprint":false},{"year":2019,"finding":"WT ClC-5 has a 2Cl-/H+ exchange stoichiometry at +40 mV; the S244L variant shows altered stoichiometry (~1.6:1) and reduced Cl-/H+ transport; R345W has slightly higher transport than S244L but is retained in early endosomes; Q629* is retained in ER/cis-Golgi and shows minimal transport. ClC-5 transport is self-inhibitory (provides net negative charges) but facilitates H+-ATPase-mediated endosomal acidification in a burst mode.","method":"Ion-selective microelectrodes in Xenopus oocytes; eGFP-tagged protein localization with organelle probes in HEK293 cells; chemiluminescent surface expression assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct stoichiometry measurement plus subcellular trafficking analysis for multiple variants in single study","pmids":["31852738"],"is_preprint":false},{"year":1998,"finding":"ClC-5 protein is localized to intracellular endosomal compartments (outer medullary endosomes) in the S3 segment of the proximal tubule and medullary thick ascending limb of rat kidney, as established by isoform-specific antiserum and subcellular membrane fractionation.","method":"Subcellular membrane fractionation; flow cytometry; immunohistochemistry with isoform-specific antibody; in situ hybridization","journal":"The American journal of physiology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — subcellular fractionation plus immunohistochemistry, confirmed by multiple subsequent studies","pmids":["9815133"],"is_preprint":false}],"current_model":"ClC-5 (CLCN5) is an electrogenic 2Cl⁻/1H⁺ exchanger resident in apical endosomes of renal proximal tubule cells, where it facilitates endosomal acidification by providing electrical shunting for the vacuolar H⁺-ATPase and by directly transporting H⁺ into the endosomal lumen; it is essential for both receptor-mediated and fluid-phase endocytosis, regulates surface trafficking of NHE3 (via exocytosis), megalin/cubilin, and NaPi-2, and is regulated by its C-terminal PY-like motif (interacting with WWP2/Nedd4-2 ubiquitin ligases), NHERF2 scaffolding, KIF3B-dependent microtubular transport, and ATP binding to its CBS domains; loss-of-function mutations cause Dent's disease through defective proximal tubular endocytosis with secondary effects on calciotropic hormones, phosphate handling, and vitamin D metabolism."},"narrative":{"mechanistic_narrative":"CLCN5 (ClC-5) is a member of the CLC family of chloride transport proteins that functions as the principal electrogenic 2Cl⁻/H⁺ exchanger of apical endosomes in the renal proximal tubule, where it is essential for receptor-mediated and fluid-phase endocytosis [PMID:7874126, PMID:11099045]. Originally identified by positional cloning as the gene deleted in Dent's disease [PMID:7874126], ClC-5 was first shown by heterologous expression to carry strongly outwardly rectifying anion currents with a NO3⁻ > Cl⁻ > Br⁻ > I⁻ selectivity, with permeation governed by residues in transmembrane domains D2 and D3 [PMID:8537381, PMID:9873029]. ClC-5 resides in early/recycling endosomes alongside the vacuolar H⁺-ATPase, internalized ligands, and Rab markers [PMID:9653142, PMID:9931332, PMID:9815133], where it supports endosomal acidification both by providing an electrical shunt for the V-ATPase and by directly exchanging luminal Cl⁻ for cytoplasmic H⁺, contributing a bafilomycin-insensitive acidification component [PMID:12548389, PMID:20421284, PMID:27044412]. Genetic disruption in mice abolishes apical proximal tubular endocytosis, causing proteinuria, and produces a downstream endocrine cascade in which defective ligand uptake elevates luminal PTH and drives phosphaturia via internalization of NaPi transporters [PMID:11099045, PMID:12548389]. Transport mechanism rests on coupled gating glutamates: the gating glutamate E211 senses extracellular protons and is protonated through the proton glutamate E268, coupling H⁺ movement to Cl⁻ exchange [PMID:20513761, PMID:22267722]. Surface delivery and trafficking are controlled by ATP binding to the C-terminal CBS domains, which drives a conformational compaction promoting ER exit and biosynthetic maturation [PMID:16686597, PMID:21173145], and by C-terminal interactions with the NHERF2 scaffold, megalin, and the kinesin motor KIF3B [PMID:16601121, PMID:19940036, PMID:22349218]. Loss-of-function CLCN5 mutations cause Dent's disease through several distinct mechanisms — ER retention and proteasomal degradation of misfolded protein, defective endosomal targeting, or selective loss of H⁺ coupling that converts ClC-5 into a pure Cl⁻ channel — establishing that impaired endocytosis, not endosomal acidification alone, underlies the disease [PMID:15942052, PMID:19019917, PMID:23566014, PMID:27044412, PMID:29791050].","teleology":[{"year":1994,"claim":"Established CLCN5 as a candidate disease gene by linking a novel kidney-expressed CLC family member to genomic deletion in Dent's disease, defining the gene of interest.","evidence":"Positional cloning by YAC/cDNA screening with deletion mapping in patients","pmids":["7874126"],"confidence":"High","gaps":["Did not establish transport function or subcellular localization","Mechanism linking gene loss to renal phenotype unknown"]},{"year":1995,"claim":"Demonstrated that ClC-5 carries intrinsic anion current, answering whether it is a functional transport protein and defining its ion selectivity.","evidence":"Heterologous expression in Xenopus oocytes with two-electrode voltage clamp","pmids":["8537381"],"confidence":"High","gaps":["Did not resolve whether activity is channel- or exchanger-based","Native subcellular site of activity not addressed"]},{"year":1998,"claim":"Placed ClC-5 in endosomal compartments alongside the V-ATPase and endocytosed ligands, establishing the cellular context for its function in renal endocytosis.","evidence":"Immunofluorescence colocalization, rab5 mutant cotransfection, and subcellular fractionation in kidney","pmids":["9653142","9815133"],"confidence":"High","gaps":["Causal role in acidification not yet tested","Whether ClB-5 is required for endocytosis untested"]},{"year":1999,"claim":"Mapped permeation-pathway residues (S168, E211) and confirmed plasma-membrane current, providing the first structure-function link for ion handling.","evidence":"Site-directed mutagenesis with two-electrode voltage clamp and HEK293 patch clamp","pmids":["9873029","9931332"],"confidence":"High","gaps":["Coupling of anion permeation to proton transport not yet defined","Endosomal versus surface functional roles unresolved"]},{"year":2000,"claim":"Demonstrated genetically that ClC-5 is essential for apical proximal tubular endocytosis and for trafficking of apical transporters, establishing the in vivo pathophysiology.","evidence":"Clcn5 knockout mouse with endocytosis assays and transporter localization","pmids":["11099045"],"confidence":"High","gaps":["Molecular mechanism connecting transport activity to endocytic defect unresolved","Direct endosomal pH measurement not yet performed"]},{"year":2000,"claim":"Identified a C-terminal PY-like motif controlling surface expression through WWP2-mediated internalization, addressing how ClC-5 trafficking is regulated.","evidence":"PY-motif mutagenesis with dominant-negative WWP2 and electrophysiology in oocytes","pmids":["11116157"],"confidence":"High","gaps":["Physiological relevance not yet tested in vivo (later contradicted)","Identity of additional ligases not addressed"]},{"year":2002,"claim":"Directly confirmed ClC-5's role in endosomal acidification and traced the cascade to PTH-driven phosphaturia, linking transport to systemic phenotype.","evidence":"Clcn5 KO mouse endosomal acidification assay with hormone measurements","pmids":["12548389"],"confidence":"High","gaps":["Whether ClC-5 itself transports protons or only shunts charge unresolved","Quantitative contribution to acidification not partitioned"]},{"year":2003,"claim":"Showed loss of ClC-5 inverts V-ATPase polarity in patient tubules, indicating a role in maintaining proton-pump distribution.","evidence":"Immunohistochemistry of Dent's disease renal biopsies","pmids":["12631345"],"confidence":"Medium","gaps":["Single lab, no functional rescue","Causality versus secondary effect not established"]},{"year":2004,"claim":"Identified Nedd4-2 as a direct C-terminal ubiquitin-ligase partner regulating ClC-5 surface expression and albumin uptake, expanding the trafficking-regulation network.","evidence":"Co-IP, GST pull-down, oocyte electrophysiology, and siRNA albumin uptake assays","pmids":["15489223"],"confidence":"High","gaps":["In vivo requirement of ubiquitylation untested (later contradicted)","Relationship to WWP2 pathway unclear"]},{"year":2005,"claim":"Demonstrated by rescue that disease mutants fail to restore endocytosis due to defective targeting, mechanistically linking specific mutations to functional loss.","evidence":"Adenoviral re-expression of WT and mutant ClC-5 in KO proximal tubule cells with endocytosis and biotinylation assays","pmids":["15942052"],"confidence":"High","gaps":["Structural basis of mistargeting not resolved","Not all mutation classes covered"]},{"year":2005,"claim":"Identified NHERF2 (but not NHERF1) as a PDZ-domain scaffold that promotes ClC-5 surface retention and endocytosis, defining a scaffolding control point.","evidence":"Co-IP, GST pull-down, and siRNA with surface biotinylation and albumin uptake assays in OK cells","pmids":["16601121"],"confidence":"High","gaps":["In vivo relevance not established","Opposing NHERF1/NHERF2 mechanism not fully resolved"]},{"year":2006,"claim":"Showed the C-terminal CBS-containing domain directly binds ATP and is stabilized by it, identifying a nucleotide-sensing regulatory module.","evidence":"Radiolabeled ATP binding, CD spectroscopy, and thermal stability with purified C-terminal domain","pmids":["16686597"],"confidence":"High","gaps":["Functional consequence of ATP binding for the full channel not yet defined","Physiological ATP-sensitivity range untested"]},{"year":2008,"claim":"Classified Dent's disease mutations into three functional/structural categories, providing a framework for genotype-mechanism correlation.","evidence":"Electrophysiology, confocal localization, acidification assays, and homology modeling of seven mutants","pmids":["19019917"],"confidence":"High","gaps":["Atomic structure not available to confirm modeling","Class boundaries based on limited mutant set"]},{"year":2009,"claim":"Identified KIF3B as a kinesin motor partner driving microtubule-based trafficking of ClC-5 vesicles, defining the cytoskeletal transport mechanism.","evidence":"Yeast two-hybrid, reciprocal co-IP, live-cell imaging, and siRNA endocytosis assays","pmids":["19940036"],"confidence":"High","gaps":["In vivo requirement of KIF3B for ClC-5 function untested","Coordination with scaffold/ubiquitin pathways unclear"]},{"year":2010,"claim":"Resolved that ClC-5 directly acidifies endosomes as a Cl⁻/H⁺ exchanger, providing a bafilomycin-insensitive acidification component beyond electrical shunting.","evidence":"Whole-cell patch clamp, endosome-targeted pH sensors, transport-dead mutagenesis, and siRNA in proximal tubule cells","pmids":["20421284"],"confidence":"High","gaps":["Quantitative balance of shunt versus direct H⁺ transport not partitioned","Stoichiometry under physiological voltages not yet measured"]},{"year":2010,"claim":"Overturned the heterologous-expression model of PY-motif ubiquitylation by showing it is dispensable for endocytosis in vivo, refining the regulatory model.","evidence":"PY-motif knock-in mouse with urine, endocytosis, and transporter localization analyses","pmids":["20351103"],"confidence":"High","gaps":["Reason for discrepancy with oocyte/cell studies unresolved","Whether ubiquitylation matters under stress conditions untested"]},{"year":2010,"claim":"Defined intrinsic voltage sensing and anion-coupled gating, and localized extracellular proton inhibition to gating glutamate E211, dissecting the transport cycle.","evidence":"Gating-current recordings of permeation-deficient mutant, ion substitution, and SCN⁻ uncoupling with pH manipulation","pmids":["20501796","20513761"],"confidence":"High","gaps":["Atomic-resolution gating-state structures not available","Coupling to in-cell endosomal conditions not directly measured"]},{"year":2010,"claim":"Showed ATP binding induces clamp-like compaction of the C-terminus that promotes ER exit and maturation, linking nucleotide sensing to biosynthetic trafficking.","evidence":"SAXS, limited proteolysis, Y617A mutagenesis, and trafficking assays in fibroblasts and tubule cells","pmids":["21173145"],"confidence":"High","gaps":["Structure of nucleotide-bound full-length protein unresolved","Physiological ATP fluctuations controlling trafficking untested"]},{"year":2011,"claim":"Revealed an exocytic role for ClC-5 in NHE3 surface delivery, broadening its function beyond endocytosis.","evidence":"shRNA in OK cells with exocytosis/endocytosis biotinylation, plus two-photon NHE3 activity in KO mice","pmids":["21561868"],"confidence":"High","gaps":["Molecular link between ClC-5 transport and exocytic machinery unknown","Generality to other exocytosed cargo untested"]},{"year":2012,"claim":"Demonstrated a three-protein ClC-5/megalin/NHERF2 complex, mechanistically connecting ClC-5 to the receptor-endocytosis machinery.","evidence":"GST pull-down, endogenous co-IP from kidney lysate, NHERF2 siRNA, and fusion-protein reconstitution","pmids":["22349218"],"confidence":"High","gaps":["Stoichiometry and dynamics of the complex in vivo unresolved","Functional consequence for megalin recycling not directly measured"]},{"year":2012,"claim":"Established that proton glutamate E268 mediates protonation of gating glutamate E211, defining the molecular coupling between H⁺ and Cl⁻ transport.","evidence":"Charge-coupled mutagenesis, gating-charge measurements, and sulfhydryl modification","pmids":["22267722"],"confidence":"High","gaps":["Structural confirmation of the protonation pathway absent","Behavior at native endosomal pH not directly tested"]},{"year":2013,"claim":"Showed specific disease mutants are misfolded and proteasomally degraded, defining a degradation-based disease mechanism for membrane and C-terminal mutations.","evidence":"Limited proteolysis, proteasome inhibition, and polyubiquitination IP in OK cells","pmids":["23566014"],"confidence":"High","gaps":["Quality-control machinery recognizing the mutants unidentified","Whether chaperone rescue is feasible untested"]},{"year":2016,"claim":"Demonstrated functional coupling between ClC-5 and the V-ATPase, showing a pure-Cl⁻-channel mutant still causes disease via insufficient V-ATPase activation.","evidence":"Oocyte electrophysiology, surface pH, and V-ATPase activation assays in cells and native tubules","pmids":["27044412"],"confidence":"High","gaps":["Mechanism of physical/functional V-ATPase coupling unresolved","Relative contribution of H⁺ coupling versus charge shunt in vivo unquantified"]},{"year":2018,"claim":"Showed a gating-glutamate mutant that preserves trafficking and endosomal pH yet causes disease, establishing that impaired acidification is not the sole disease mechanism.","evidence":"Oocyte and HEK293T electrophysiology, glycosylation/localization analysis, and pHluorin2 endosomal pH measurement","pmids":["29791050"],"confidence":"High","gaps":["Alternative disease-causing function of Cl⁻/H⁺ exchange unidentified","In vivo phenotype of this variant untested"]},{"year":2019,"claim":"Measured native 2Cl⁻/H⁺ stoichiometry and showed variant-specific alterations in transport and trafficking, refining the quantitative transport model.","evidence":"Ion-selective microelectrodes in oocytes and organelle-probe localization with surface-expression assays for multiple variants","pmids":["31852738"],"confidence":"High","gaps":["Burst-mode acidification model not validated in native endosomes","Variant phenotypes not tested in animal models"]},{"year":null,"claim":"How ClC-5's Cl⁻/H⁺ exchange activity is mechanistically coupled to endocytic and exocytic membrane trafficking — beyond endosomal acidification — remains undefined.","evidence":"","pmids":[],"confidence":"High","gaps":["No atomic structure of full-length human ClC-5 in the corpus","Direct molecular link between transport activity and cargo trafficking machinery unresolved","Non-acidification disease mechanism unidentified"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[1,3,15,24,26]},{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[12,19]}],"localization":[{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[2,4,15,27]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[3,6,11]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[13,19,23]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[5,14,20]},{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[1,15,24]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[0,10,13,24]}],"complexes":[],"partners":["WWP2","NEDD4L","NHERF2","KIF3B","LRP2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P51795","full_name":"H(+)/Cl(-) exchange transporter 5","aliases":["Chloride channel protein 5","ClC-5","Chloride transporter ClC-5"],"length_aa":816,"mass_kda":90.8,"function":"Proton-coupled chloride transporter. Functions as antiport system and exchanges chloride ions against protons (PubMed:20466723). Important for normal acidification of the endosome lumen. May play an important role in renal tubular function. The CLC channel family contains both chloride channels and proton-coupled anion transporters that exchange chloride or another anion for protons. The absence of conserved gating glutamate residues is typical for family members that function as channels (Probable)","subcellular_location":"Golgi apparatus membrane; Endosome membrane; Cell membrane","url":"https://www.uniprot.org/uniprotkb/P51795/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CLCN5","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"VTI1A","stoichiometry":4.0},{"gene":"RAB7A","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/CLCN5","total_profiled":1310},"omim":[{"mim_id":"430000","title":"INTERLEUKIN 3 RECEPTOR, Y-CHROMOSOMAL; IL3RA","url":"https://www.omim.org/entry/430000"},{"mim_id":"314310","title":"TRANSCRIPTION FACTOR FOR IMMUNOGLOBULIN HEAVY-CHAIN ENHANCER 3; TFE3","url":"https://www.omim.org/entry/314310"},{"mim_id":"310468","title":"NEPHROLITHIASIS, X-LINKED RECESSIVE, WITH RENAL FAILURE; XRN","url":"https://www.omim.org/entry/310468"},{"mim_id":"308990","title":"PROTEINURIA, LOW MOLECULAR WEIGHT, WITH HYPERCALCIURIA AND NEPHROCALCINOSIS","url":"https://www.omim.org/entry/308990"},{"mim_id":"300555","title":"DENT DISEASE 2; DENT2","url":"https://www.omim.org/entry/300555"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Golgi apparatus","reliability":"Supported"},{"location":"Plasma membrane","reliability":"Supported"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"epididymis","ntpm":22.3},{"tissue":"kidney","ntpm":43.1},{"tissue":"liver","ntpm":15.8}],"url":"https://www.proteinatlas.org/search/CLCN5"},"hgnc":{"alias_symbol":["DENTS","XLRH","hClC-K2","hCIC-K2","CLC5","XRN","ClC-5"],"prev_symbol":["NPHL2","NPHL1"]},"alphafold":{"accession":"P51795","domains":[{"cath_id":"1.10.3080.10","chopping":"131-364","consensus_level":"medium","plddt":89.2516,"start":131,"end":364},{"cath_id":"1.10.3080.10","chopping":"389-473_487-634","consensus_level":"high","plddt":88.908,"start":389,"end":634},{"cath_id":"3.10.580.20","chopping":"651-805","consensus_level":"high","plddt":86.6072,"start":651,"end":805}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P51795","model_url":"https://alphafold.ebi.ac.uk/files/AF-P51795-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P51795-F1-predicted_aligned_error_v6.png","plddt_mean":80.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CLCN5","jax_strain_url":"https://www.jax.org/strain/search?query=CLCN5"},"sequence":{"accession":"P51795","fasta_url":"https://rest.uniprot.org/uniprotkb/P51795.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P51795/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P51795"}},"corpus_meta":[{"pmid":"11099045","id":"PMC_11099045","title":"ClC-5 Cl- -channel disruption impairs endocytosis in a mouse model for Dent's disease.","date":"2000","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/11099045","citation_count":435,"is_preprint":false},{"pmid":"9653142","id":"PMC_9653142","title":"ClC-5, the chloride channel mutated in Dent's disease, colocalizes with the proton pump in endocytotically active kidney cells.","date":"1998","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/9653142","citation_count":362,"is_preprint":false},{"pmid":"9931332","id":"PMC_9931332","title":"Intra-renal and subcellular distribution of the human chloride channel, CLC-5, reveals a pathophysiological basis for Dent's disease.","date":"1999","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/9931332","citation_count":241,"is_preprint":false},{"pmid":"8537381","id":"PMC_8537381","title":"Cloning and functional expression of rat CLC-5, a chloride channel related to kidney disease.","date":"1995","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/8537381","citation_count":239,"is_preprint":false},{"pmid":"9873029","id":"PMC_9873029","title":"Mutational analysis demonstrates that ClC-4 and ClC-5 directly mediate plasma membrane currents.","date":"1999","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9873029","citation_count":209,"is_preprint":false},{"pmid":"20946626","id":"PMC_20946626","title":"Dent's disease.","date":"2010","source":"Orphanet journal of rare diseases","url":"https://pubmed.ncbi.nlm.nih.gov/20946626","citation_count":170,"is_preprint":false},{"pmid":"12548389","id":"PMC_12548389","title":"The ClC-5 chloride channel knock-out mouse - an animal model for Dent's disease.","date":"2002","source":"Pflugers Archiv : European journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/12548389","citation_count":159,"is_preprint":false},{"pmid":"9259268","id":"PMC_9259268","title":"Characterisation of renal chloride channel, CLCN5, mutations in hypercalciuric nephrolithiasis (kidney stones) disorders.","date":"1997","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/9259268","citation_count":135,"is_preprint":false},{"pmid":"7874126","id":"PMC_7874126","title":"Isolation and partial characterization of a chloride channel gene which is expressed in kidney and is a candidate for Dent's disease (an X-linked hereditary nephrolithiasis).","date":"1994","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/7874126","citation_count":135,"is_preprint":false},{"pmid":"8575751","id":"PMC_8575751","title":"Cloning and characterization of CLCN5, the human kidney chloride channel gene implicated in Dent disease (an X-linked hereditary nephrolithiasis).","date":"1995","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/8575751","citation_count":125,"is_preprint":false},{"pmid":"9062355","id":"PMC_9062355","title":"Idiopathic low molecular weight proteinuria associated with hypercalciuric nephrocalcinosis in Japanese children is due to mutations of the renal chloride channel (CLCN5).","date":"1997","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/9062355","citation_count":121,"is_preprint":false},{"pmid":"11116157","id":"PMC_11116157","title":"An internalization signal in ClC-5, an endosomal Cl-channel mutated in dent's disease.","date":"2000","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11116157","citation_count":114,"is_preprint":false},{"pmid":"15086899","id":"PMC_15086899","title":"Evidence for genetic heterogeneity in Dent's disease.","date":"2004","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/15086899","citation_count":89,"is_preprint":false},{"pmid":"10620205","id":"PMC_10620205","title":"Tubular proteinuria defined by a study of Dent's (CLCN5 mutation) and other tubular diseases.","date":"2000","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/10620205","citation_count":87,"is_preprint":false},{"pmid":"20936522","id":"PMC_20936522","title":"Dent's disease: clinical features and molecular basis.","date":"2010","source":"Pediatric nephrology (Berlin, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/20936522","citation_count":79,"is_preprint":false},{"pmid":"10720930","id":"PMC_10720930","title":"Pathogenesis of Dent's disease and related syndromes of X-linked nephrolithiasis.","date":"2000","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/10720930","citation_count":78,"is_preprint":false},{"pmid":"25907713","id":"PMC_25907713","title":"Mutation Update of the CLCN5 Gene Responsible for Dent Disease 1.","date":"2015","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/25907713","citation_count":77,"is_preprint":false},{"pmid":"15489223","id":"PMC_15489223","title":"Nedd4-2 functionally interacts with ClC-5: involvement in constitutive albumin endocytosis in proximal tubule cells.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15489223","citation_count":75,"is_preprint":false},{"pmid":"9853249","id":"PMC_9853249","title":"Functional characterization of renal chloride channel, CLCN5, mutations associated with Dent'sJapan disease.","date":"1998","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/9853249","citation_count":67,"is_preprint":false},{"pmid":"12631345","id":"PMC_12631345","title":"Altered polarity and expression of H+-ATPase without ultrastructural changes in kidneys of Dent's disease patients.","date":"2003","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/12631345","citation_count":67,"is_preprint":false},{"pmid":"12444212","id":"PMC_12444212","title":"Responsiveness of hypercalciuria to thiazide in Dent's disease.","date":"2002","source":"Journal of the American Society of Nephrology : JASN","url":"https://pubmed.ncbi.nlm.nih.gov/12444212","citation_count":65,"is_preprint":false},{"pmid":"9328929","id":"PMC_9328929","title":"Mutations of CLCN5 in Japanese children with idiopathic low molecular weight proteinuria, hypercalciuria and nephrocalcinosis.","date":"1997","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/9328929","citation_count":64,"is_preprint":false},{"pmid":"22695891","id":"PMC_22695891","title":"Mutational analysis of PHEX, FGF23, DMP1, SLC34A3 and CLCN5 in patients with hypophosphatemic rickets.","date":"2012","source":"Journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/22695891","citation_count":63,"is_preprint":false},{"pmid":"9815133","id":"PMC_9815133","title":"Intrarenal and subcellular localization of rat CLC5.","date":"1998","source":"The American journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/9815133","citation_count":56,"is_preprint":false},{"pmid":"9734595","id":"PMC_9734595","title":"CLCN5 chloride-channel mutations in six new North American families with X-linked nephrolithiasis.","date":"1998","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/9734595","citation_count":56,"is_preprint":false},{"pmid":"10518595","id":"PMC_10518595","title":"Diet-dependent hypercalciuria in transgenic mice with reduced CLC5 chloride channel expression.","date":"1999","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/10518595","citation_count":55,"is_preprint":false},{"pmid":"9596078","id":"PMC_9596078","title":"Mutations in CLCN5 chloride channel in Japanese patients with low molecular weight proteinuria.","date":"1998","source":"Journal of the American Society of Nephrology : JASN","url":"https://pubmed.ncbi.nlm.nih.gov/9596078","citation_count":52,"is_preprint":false},{"pmid":"16822791","id":"PMC_16822791","title":"Phenotypic and genetic heterogeneity in Dent's disease--the results of an Italian collaborative study.","date":"2006","source":"Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association","url":"https://pubmed.ncbi.nlm.nih.gov/16822791","citation_count":52,"is_preprint":false},{"pmid":"19940036","id":"PMC_19940036","title":"CLC-5 and KIF3B interact to facilitate CLC-5 plasma membrane expression, endocytosis, and microtubular transport: relevance to pathophysiology of Dent's disease.","date":"2009","source":"American journal of physiology. Renal physiology","url":"https://pubmed.ncbi.nlm.nih.gov/19940036","citation_count":51,"is_preprint":false},{"pmid":"15942052","id":"PMC_15942052","title":"ClC-5: role in endocytosis in the proximal tubule.","date":"2005","source":"American journal of physiology. Renal physiology","url":"https://pubmed.ncbi.nlm.nih.gov/15942052","citation_count":51,"is_preprint":false},{"pmid":"19019917","id":"PMC_19019917","title":"Characterization of Dent's disease mutations of CLC-5 reveals a correlation between functional and cell biological consequences and protein structure.","date":"2008","source":"American journal of physiology. Renal physiology","url":"https://pubmed.ncbi.nlm.nih.gov/19019917","citation_count":49,"is_preprint":false},{"pmid":"16601121","id":"PMC_16601121","title":"Regulation of albumin endocytosis by PSD95/Dlg/ZO-1 (PDZ) scaffolds. Interaction of Na+-H+ exchange regulatory factor-2 with ClC-5.","date":"2006","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16601121","citation_count":49,"is_preprint":false},{"pmid":"10620204","id":"PMC_10620204","title":"Isolated hypercalciuria with mutation in CLCN5: relevance to idiopathic hypercalciuria.","date":"2000","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/10620204","citation_count":47,"is_preprint":false},{"pmid":"22083641","id":"PMC_22083641","title":"ClC-5 mutations associated with Dent's disease: a major role of the dimer interface.","date":"2011","source":"Pflugers Archiv : European journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/22083641","citation_count":47,"is_preprint":false},{"pmid":"10906159","id":"PMC_10906159","title":"Characterization of renal chloride channel (CLCN5) mutations in Dent's disease.","date":"2000","source":"Journal of the American Society of Nephrology : JASN","url":"https://pubmed.ncbi.nlm.nih.gov/10906159","citation_count":47,"is_preprint":false},{"pmid":"15895257","id":"PMC_15895257","title":"Functional evaluation of Dent's disease-causing mutations: implications for ClC-5 channel trafficking and internalization.","date":"2005","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/15895257","citation_count":47,"is_preprint":false},{"pmid":"25909590","id":"PMC_25909590","title":"IL-4 Up-Regulates MiR-21 and the MiRNAs Hosted in the CLCN5 Gene in Chronic Lymphocytic Leukemia.","date":"2015","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25909590","citation_count":46,"is_preprint":false},{"pmid":"10191359","id":"PMC_10191359","title":"Comparison of amphibian and human ClC-5: similarity of functional properties and inhibition by external pH.","date":"1999","source":"The Journal of membrane biology","url":"https://pubmed.ncbi.nlm.nih.gov/10191359","citation_count":42,"is_preprint":false},{"pmid":"20351103","id":"PMC_20351103","title":"Role of ClC-5 in renal endocytosis is unique among ClC exchangers and does not require PY-motif-dependent ubiquitylation.","date":"2010","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/20351103","citation_count":41,"is_preprint":false},{"pmid":"16226913","id":"PMC_16226913","title":"ClC-5: a chloride channel with multiple roles in renal tubular albumin uptake.","date":"2005","source":"The international journal of biochemistry & cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/16226913","citation_count":40,"is_preprint":false},{"pmid":"10916075","id":"PMC_10916075","title":"Clinical and genetic studies of CLCN5 mutations in Japanese families with Dent's disease.","date":"2000","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/10916075","citation_count":39,"is_preprint":false},{"pmid":"16807762","id":"PMC_16807762","title":"Hypercalciuria in patients with CLCN5 mutations.","date":"2006","source":"Pediatric nephrology (Berlin, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/16807762","citation_count":39,"is_preprint":false},{"pmid":"19657328","id":"PMC_19657328","title":"Novel CLCN5 mutations in patients with Dent's disease result in altered ion currents or impaired exchanger processing.","date":"2009","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/19657328","citation_count":39,"is_preprint":false},{"pmid":"9328927","id":"PMC_9328927","title":"Mutations in the CLCN5 gene in Japanese patients with familial idiopathic low-molecular-weight proteinuria.","date":"1997","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/9328927","citation_count":39,"is_preprint":false},{"pmid":"20421284","id":"PMC_20421284","title":"Direct endosomal acidification by the outwardly rectifying CLC-5 Cl(-)/H(+) exchanger.","date":"2010","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/20421284","citation_count":39,"is_preprint":false},{"pmid":"20501796","id":"PMC_20501796","title":"Voltage-dependent charge movement associated with activation of the CLC-5 2Cl-/1H+ exchanger.","date":"2010","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/20501796","citation_count":39,"is_preprint":false},{"pmid":"23029130","id":"PMC_23029130","title":"Involvement of the tubular ClC-type exchanger ClC-5 in glomeruli of human proteinuric nephropathies.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23029130","citation_count":35,"is_preprint":false},{"pmid":"9452997","id":"PMC_9452997","title":"CLCN5 mutation Ser244Leu is associated with X-linked renal failure without X-linked recessive hypophosphatemic rickets.","date":"1998","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/9452997","citation_count":34,"is_preprint":false},{"pmid":"20680351","id":"PMC_20680351","title":"A novel CLCN5 mutation in a boy with Bartter-like syndrome and partial growth hormone deficiency.","date":"2010","source":"Pediatric nephrology (Berlin, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/20680351","citation_count":34,"is_preprint":false},{"pmid":"32289351","id":"PMC_32289351","title":"From protein uptake to Dent disease: An overview of the CLCN5 gene.","date":"2020","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/32289351","citation_count":33,"is_preprint":false},{"pmid":"26389017","id":"PMC_26389017","title":"Nephrolithiasis, kidney failure and bone disorders in Dent disease patients with and without CLCN5 mutations.","date":"2015","source":"SpringerPlus","url":"https://pubmed.ncbi.nlm.nih.gov/26389017","citation_count":33,"is_preprint":false},{"pmid":"15637424","id":"PMC_15637424","title":"Chloride channels and endocytosis: new insights from Dent's disease and ClC-5 knockout mice.","date":"2005","source":"Nephron. Physiology","url":"https://pubmed.ncbi.nlm.nih.gov/15637424","citation_count":33,"is_preprint":false},{"pmid":"12637640","id":"PMC_12637640","title":"Novel truncating mutations in the ClC-5 chloride channel gene in patients with Dent's disease.","date":"2003","source":"Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association","url":"https://pubmed.ncbi.nlm.nih.gov/12637640","citation_count":33,"is_preprint":false},{"pmid":"11136179","id":"PMC_11136179","title":"Identification of two novel mutations in the CLCN5 gene in Japanese patients with familial idiopathic low molecular weight proteinuria (Japanese Dent's disease).","date":"2001","source":"American journal of kidney diseases : the official journal of the National Kidney Foundation","url":"https://pubmed.ncbi.nlm.nih.gov/11136179","citation_count":31,"is_preprint":false},{"pmid":"20576581","id":"PMC_20576581","title":"Cadmium impairs albumin reabsorption by down-regulating megalin and ClC5 channels in renal proximal tubule cells.","date":"2010","source":"Environmental health perspectives","url":"https://pubmed.ncbi.nlm.nih.gov/20576581","citation_count":30,"is_preprint":false},{"pmid":"14569459","id":"PMC_14569459","title":"De novo insertion of an Alu sequence in the coding region of the CLCN5 gene results in Dent's disease.","date":"2003","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/14569459","citation_count":30,"is_preprint":false},{"pmid":"16041495","id":"PMC_16041495","title":"The Alu insertion in the CLCN5 gene of a patient with Dent's disease leads to exon 11 skipping.","date":"2005","source":"Journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/16041495","citation_count":30,"is_preprint":false},{"pmid":"10469281","id":"PMC_10469281","title":"Renal chloride channel, CLCN5, mutations in Dent's disease.","date":"1999","source":"Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research","url":"https://pubmed.ncbi.nlm.nih.gov/10469281","citation_count":29,"is_preprint":false},{"pmid":"19546591","id":"PMC_19546591","title":"Mutational analysis of CLC-5, cofilin and CLC-4 in patients with Dent's disease.","date":"2009","source":"Nephron. Physiology","url":"https://pubmed.ncbi.nlm.nih.gov/19546591","citation_count":28,"is_preprint":false},{"pmid":"18349385","id":"PMC_18349385","title":"Transcriptional adaptation to Clcn5 knockout in proximal tubules of mouse kidney.","date":"2008","source":"Physiological genomics","url":"https://pubmed.ncbi.nlm.nih.gov/18349385","citation_count":27,"is_preprint":false},{"pmid":"9187673","id":"PMC_9187673","title":"A second family with XLRH displays the mutation S244L in the CLCN5 gene.","date":"1997","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/9187673","citation_count":26,"is_preprint":false},{"pmid":"21305656","id":"PMC_21305656","title":"Heterogeneity in the processing of CLCN5 mutants related to Dent disease.","date":"2011","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/21305656","citation_count":26,"is_preprint":false},{"pmid":"19582483","id":"PMC_19582483","title":"Locus heterogeneity of Dent's disease: OCRL1 and TMEM27 genes in patients with no CLCN5 mutations.","date":"2009","source":"Pediatric nephrology (Berlin, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/19582483","citation_count":26,"is_preprint":false},{"pmid":"21932010","id":"PMC_21932010","title":"A patient with Dent disease and features of Bartter syndrome caused by a novel mutation of CLCN5.","date":"2011","source":"European journal of pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/21932010","citation_count":26,"is_preprint":false},{"pmid":"25443653","id":"PMC_25443653","title":"ClC-5: Physiological role and biophysical mechanisms.","date":"2014","source":"Cell calcium","url":"https://pubmed.ncbi.nlm.nih.gov/25443653","citation_count":25,"is_preprint":false},{"pmid":"22349218","id":"PMC_22349218","title":"The interaction between megalin and ClC-5 is scaffolded by the Na⁺-H⁺ exchanger regulatory factor 2 (NHERF2) in proximal tubule cells.","date":"2012","source":"The international journal of biochemistry & cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/22349218","citation_count":25,"is_preprint":false},{"pmid":"30426109","id":"PMC_30426109","title":"A Novel CLCN5 Mutation Associated With Focal Segmental Glomerulosclerosis and Podocyte Injury.","date":"2018","source":"Kidney international reports","url":"https://pubmed.ncbi.nlm.nih.gov/30426109","citation_count":24,"is_preprint":false},{"pmid":"28383812","id":"PMC_28383812","title":"Mutational analysis of PHEX, FGF23 and CLCN5 in patients with hypophosphataemic rickets.","date":"2017","source":"Clinical endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/28383812","citation_count":24,"is_preprint":false},{"pmid":"11263994","id":"PMC_11263994","title":"Expression of chloride channel, ClC-5, and its role in receptor-mediated endocytosis of albumin in OK cells.","date":"2001","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/11263994","citation_count":23,"is_preprint":false},{"pmid":"20513761","id":"PMC_20513761","title":"Proton block of the CLC-5 Cl-/H+ exchanger.","date":"2010","source":"The Journal of general physiology","url":"https://pubmed.ncbi.nlm.nih.gov/20513761","citation_count":23,"is_preprint":false},{"pmid":"15047167","id":"PMC_15047167","title":"Expression and roles of Cl- channel ClC-5 in cell cycles of myeloid cells.","date":"2004","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/15047167","citation_count":22,"is_preprint":false},{"pmid":"16686597","id":"PMC_16686597","title":"Nucleotides bind to the C-terminus of ClC-5.","date":"2006","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/16686597","citation_count":22,"is_preprint":false},{"pmid":"9893114","id":"PMC_9893114","title":"Chloride channel CLCN5 mutations in Japanese children with familial idiopathic low molecular weight proteinuria.","date":"1999","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/9893114","citation_count":22,"is_preprint":false},{"pmid":"23047739","id":"PMC_23047739","title":"An atypical Dent's disease phenotype caused by co-inheritance of mutations at CLCN5 and OCRL genes.","date":"2012","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/23047739","citation_count":22,"is_preprint":false},{"pmid":"37284679","id":"PMC_37284679","title":"The Site and Type of CLCN5 Genetic Variation Impact the Resulting Dent Disease-1 Phenotype.","date":"2023","source":"Kidney international reports","url":"https://pubmed.ncbi.nlm.nih.gov/37284679","citation_count":21,"is_preprint":false},{"pmid":"29791050","id":"PMC_29791050","title":"A novel CLCN5 pathogenic mutation supports Dent disease with normal endosomal acidification.","date":"2018","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/29791050","citation_count":21,"is_preprint":false},{"pmid":"28676554","id":"PMC_28676554","title":"Diabetic rats present higher urinary loss of proteins and lower renal expression of megalin, cubilin, ClC-5, and CFTR.","date":"2017","source":"Physiological reports","url":"https://pubmed.ncbi.nlm.nih.gov/28676554","citation_count":21,"is_preprint":false},{"pmid":"14675051","id":"PMC_14675051","title":"Comparative ontogeny, processing, and segmental distribution of the renal chloride channel, ClC-5.","date":"2004","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/14675051","citation_count":21,"is_preprint":false},{"pmid":"18025833","id":"PMC_18025833","title":"Functional characterization of a novel missense CLCN5 mutation causing alterations in proximal tubular endocytic machinery in Dent's disease.","date":"2007","source":"Nephron. Physiology","url":"https://pubmed.ncbi.nlm.nih.gov/18025833","citation_count":21,"is_preprint":false},{"pmid":"13679301","id":"PMC_13679301","title":"Coexpression of complementary fragments of ClC-5 and restoration of chloride channel function in a Dent's disease mutation.","date":"2003","source":"American journal of physiology. Cell physiology","url":"https://pubmed.ncbi.nlm.nih.gov/13679301","citation_count":21,"is_preprint":false},{"pmid":"28899456","id":"PMC_28899456","title":"ClC5 Decreases the Sensitivity of Multiple Myeloma Cells to Bortezomib via Promoting Prosurvival Autophagy.","date":"2017","source":"Oncology research","url":"https://pubmed.ncbi.nlm.nih.gov/28899456","citation_count":20,"is_preprint":false},{"pmid":"23566014","id":"PMC_23566014","title":"Conformational defects underlie proteasomal degradation of Dent's disease-causing mutants of ClC-5.","date":"2013","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/23566014","citation_count":20,"is_preprint":false},{"pmid":"22267722","id":"PMC_22267722","title":"Glutamate 268 regulates transport probability of the anion/proton exchanger ClC-5.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22267722","citation_count":20,"is_preprint":false},{"pmid":"20181886","id":"PMC_20181886","title":"Clcn5 knockout mice exhibit novel immunomodulatory effects and are more susceptible to dextran sulfate sodium-induced colitis.","date":"2010","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/20181886","citation_count":19,"is_preprint":false},{"pmid":"21561868","id":"PMC_21561868","title":"Chloride channel (Clc)-5 is necessary for exocytic trafficking of Na+/H+ exchanger 3 (NHE3).","date":"2011","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21561868","citation_count":19,"is_preprint":false},{"pmid":"21927812","id":"PMC_21927812","title":"Decreased renal accumulation of aminoglycoside reflects defective receptor-mediated endocytosis in cystic fibrosis and Dent's disease.","date":"2011","source":"Pflugers Archiv : European journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/21927812","citation_count":19,"is_preprint":false},{"pmid":"31947599","id":"PMC_31947599","title":"Genetic Analyses in Dent Disease and Characterization of CLCN5 Mutations in Kidney Biopsies.","date":"2020","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/31947599","citation_count":18,"is_preprint":false},{"pmid":"27044412","id":"PMC_27044412","title":"A pure chloride channel mutant of CLC-5 causes Dent's disease via insufficient V-ATPase activation.","date":"2016","source":"Pflugers Archiv : European journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/27044412","citation_count":18,"is_preprint":false},{"pmid":"15719255","id":"PMC_15719255","title":"Phenotype and genotype of Dent's disease in three Korean boys.","date":"2005","source":"Pediatric nephrology (Berlin, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/15719255","citation_count":18,"is_preprint":false},{"pmid":"36441012","id":"PMC_36441012","title":"Clinical and genetic characteristics of Dent's disease type 1 in Europe.","date":"2023","source":"Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association","url":"https://pubmed.ncbi.nlm.nih.gov/36441012","citation_count":16,"is_preprint":false},{"pmid":"27117801","id":"PMC_27117801","title":"Functional and transport analyses of CLCN5 genetic changes identified in Dent disease patients.","date":"2016","source":"Physiological reports","url":"https://pubmed.ncbi.nlm.nih.gov/27117801","citation_count":16,"is_preprint":false},{"pmid":"17262170","id":"PMC_17262170","title":"A missense mutation in the chloride/proton ClC-5 antiporter gene results in increased expression of an alternative mRNA form that lacks exons 10 and 11. Identification of seven new CLCN5 mutations in patients with Dent's disease.","date":"2007","source":"Journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/17262170","citation_count":16,"is_preprint":false},{"pmid":"12886045","id":"PMC_12886045","title":"Four additional CLCN5 exons encode a widely expressed novel long CLC-5 isoform but fail to explain Dent's phenotype in patients without mutations in the short variant.","date":"2003","source":"Kidney & blood pressure research","url":"https://pubmed.ncbi.nlm.nih.gov/12886045","citation_count":16,"is_preprint":false},{"pmid":"14673707","id":"PMC_14673707","title":"Identification of a novel splice site mutation of CLCN5 gene and characterization of a new alternative 5' UTR end of ClC-5 mRNA in human renal tissue and leukocytes.","date":"2003","source":"Journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/14673707","citation_count":16,"is_preprint":false},{"pmid":"20049483","id":"PMC_20049483","title":"ClC transporters: discoveries and challenges in defining the mechanisms underlying function and regulation of ClC-5.","date":"2010","source":"Pflugers Archiv : European journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/20049483","citation_count":16,"is_preprint":false},{"pmid":"19878925","id":"PMC_19878925","title":"ClC-5 regulates dentin development through TGF-beta1 pathway.","date":"2009","source":"Archives of oral biology","url":"https://pubmed.ncbi.nlm.nih.gov/19878925","citation_count":16,"is_preprint":false},{"pmid":"31852738","id":"PMC_31852738","title":"Cl- and H+ coupling properties and subcellular localizations of wildtype and disease-associated variants of the voltage-gated Cl-/H+ exchanger ClC-5.","date":"2019","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/31852738","citation_count":16,"is_preprint":false},{"pmid":"21173145","id":"PMC_21173145","title":"ATP induces conformational changes in the carboxyl-terminal region of ClC-5.","date":"2010","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21173145","citation_count":16,"is_preprint":false},{"pmid":"32201916","id":"PMC_32201916","title":"Functional analysis of suspected splicing variants in CLCN5 gene in Dent disease 1.","date":"2020","source":"Clinical and experimental nephrology","url":"https://pubmed.ncbi.nlm.nih.gov/32201916","citation_count":15,"is_preprint":false},{"pmid":"30852663","id":"PMC_30852663","title":"Prevalence of low molecular weight proteinuria and Dent disease 1 CLCN5 mutations in proteinuric cohorts.","date":"2019","source":"Pediatric nephrology (Berlin, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/30852663","citation_count":15,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":53658,"output_tokens":6940,"usd":0.132537,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":15935,"output_tokens":6524,"usd":0.121387,"stage2_stop_reason":"end_turn"},"total_usd":0.253924,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1994,\n      \"finding\": \"CLCN5 (initially termed hCIC-K2) was identified as a novel member of the CLC family of voltage-gated chloride channels, expressed predominantly in the kidney, with its genomic region completely deleted in Dent's disease patients, establishing it as the candidate disease gene.\",\n      \"method\": \"Positional cloning using YAC screening of kidney cDNA library; evolutionary conservation analysis; deletion mapping\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — positional cloning with genomic deletion confirmation, replicated by subsequent studies identifying loss-of-function mutations\",\n      \"pmids\": [\"7874126\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"Heterologous expression of rat CLC-5 in Xenopus oocytes elicits novel, strongly outwardly rectifying anion currents with conductivity sequence NO3- > Cl- > Br- > I- >> glutamate-, establishing direct chloride channel activity; cAMP had no effect on these currents.\",\n      \"method\": \"Xenopus oocyte expression system with two-electrode voltage clamp; pharmacological manipulation of cAMP\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct electrophysiological reconstitution in oocytes, replicated across multiple subsequent studies\",\n      \"pmids\": [\"8537381\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"ClC-5 colocalizes with the vacuolar H+-ATPase (proton pump) and with internalized proteins in endocytotically active renal proximal tubule cells and alpha-intercalated cells, and in transfected cells colocalizes with endocytosed alpha2-macroglobulin and enlarges rab5-Q79L early endosomes, suggesting ClC-5 resides in early endosomes and provides an electrical shunt for endosomal acidification.\",\n      \"method\": \"Immunofluorescence colocalization; cotransfection with GTPase-deficient rab5 mutant; endosome tracking with labeled ligands\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal localization methods, replicated in multiple subsequent studies across labs\",\n      \"pmids\": [\"9653142\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Active-site mutagenesis of ClC-5 demonstrated that point mutations at the end of transmembrane domain D2 (S168T) change ion selectivity, and a mutation at D3 (E211A) changes voltage dependence and ion selectivity, directly establishing that ClC-4 and ClC-5 mediate plasma membrane currents and that these residues contribute to the ion permeation pathway.\",\n      \"method\": \"Site-directed mutagenesis; two-electrode voltage clamp in Xenopus oocytes and patch-clamp in HEK293 cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstitution with mutagenesis in two heterologous expression systems, multiple mutants tested\",\n      \"pmids\": [\"9873029\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Human CLC-5 is co-distributed with Rab4 (a recycling early endosome marker) in subcellular fractions of human kidney cortex, and colocalizes with albumin-containing endocytic vesicles in opossum kidney proximal tubule cells, placing CLC-5 in the receptor-mediated endocytic pathway.\",\n      \"method\": \"Subcellular fractionation; immunoblotting; confocal immunofluorescence microscopy with albumin endocytosis tracking\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (fractionation + confocal), human tissue validated\",\n      \"pmids\": [\"9931332\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Disruption of the mouse clcn5 gene causes proteinuria by strongly reducing apical proximal tubular endocytosis (both receptor-mediated and fluid-phase), establishing ClC-5 as essential for renal endocytosis; additionally, internalization of apical transporters NaPi-2 and NHE3 is slowed.\",\n      \"method\": \"Clcn5 knockout mouse; endocytosis assays with labeled tracers; immunohistochemistry and subcellular fractionation of NaPi-2 and NHE3\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO mouse with specific endocytic phenotype, replicated by independent groups\",\n      \"pmids\": [\"11099045\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"A carboxyl-terminal PY-like motif in ClC-5 mediates its internalization from the plasma membrane via interaction with WW domain-containing ubiquitin-protein ligase WWP2; mutation of this motif increases surface expression and currents ~2-fold, and dominant-negative WWP2 increases surface ClC-5 only when the PY motif is intact.\",\n      \"method\": \"Site-directed mutagenesis of PY motif; dominant-negative expression of WWP2; rab5 overexpression/dominant-negative studies; electrophysiology in Xenopus oocytes\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis combined with dominant-negative functional assays and multiple rab5 constructs in a single study\",\n      \"pmids\": [\"11116157\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Endosomes from Clcn5 knockout mice are acidified at a significantly lower rate than wild-type endosomes, confirming that ClC-5 provides an electrical shunt for efficient vacuolar H+-ATPase operation; defective endocytosis leads to elevated luminal PTH, causing increased endocytosis of NaPi phosphate transporter and phosphaturia.\",\n      \"method\": \"Clcn5 KO mouse; endosomal acidification assay; hormone level measurements; immunohistochemistry of NaPi\",\n      \"journal\": \"Pflugers Archiv : European journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO mouse with direct endosomal pH measurement, mechanistic cascade validated\",\n      \"pmids\": [\"12548389\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Loss of CLC-5 in Dent's disease patients is associated with inversion of H+-ATPase polarity in proximal tubule cells (basolateral rather than apical) without ultrastructural changes, demonstrating that CLC-5 is required to maintain proper H+-ATPase polarity.\",\n      \"method\": \"Immunohistochemistry of renal biopsies from Dent's disease patients; confocal microscopy\",\n      \"journal\": \"Kidney international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — single lab, human biopsy immunohistochemistry, no functional rescue experiment\",\n      \"pmids\": [\"12631345\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Nedd4-2 interacts with ClC-5 via a direct binding of the C-terminus of ClC-5 to Nedd4-2; Nedd4-2 decreases cell surface expression of ClC-5 in Xenopus oocytes; albumin stimulates ubiquitination of ClC-5 and increases its surface expression; knockdown of Nedd4-2 by siRNA reduces albumin uptake in proximal tubule cells.\",\n      \"method\": \"In vivo co-immunoprecipitation; GST pull-down; Xenopus oocyte electrophysiology; siRNA knockdown; albumin endocytosis assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal pull-down plus siRNA functional rescue, multiple orthogonal methods in single lab\",\n      \"pmids\": [\"15489223\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Adenoviral re-expression of wild-type ClC-5 rescues receptor-mediated endocytosis in ClC-5 KO proximal tubule cells, whereas disease-causing mutants (W22G, S520P, R704X) do not rescue endocytosis; S520P and R704X are not internalized normally, suggesting defective targeting/trafficking underlies Dent's disease in these cases.\",\n      \"method\": \"Adenoviral transduction of KO primary proximal tubule cells; endocytosis assay; surface biotinylation; electrophysiology\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — functional rescue in KO cells with WT and mutant constructs, multiple orthogonal assays\",\n      \"pmids\": [\"15942052\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"ClC-5 has an internal C-terminal binding site that directly interacts with the PDZ2 domain of NHERF2 (but not NHERF1); silencing NHERF2 reduces cell-surface ClC-5 and albumin uptake, whereas silencing NHERF1 increases ClC-5 surface levels and albumin endocytosis.\",\n      \"method\": \"Co-immunoprecipitation from OK cell lysate; GST fusion protein pull-down; siRNA knockdown; surface biotinylation; albumin endocytosis assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct interaction mapping with GST pull-down plus siRNA functional data, single lab with multiple methods\",\n      \"pmids\": [\"16601121\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"The C-terminus of ClC-5 (containing CBS domains) directly binds ATP with low millimolar affinity; ATP and AMP binding induces no change in secondary structure but increases thermal stability of the C-terminal domain.\",\n      \"method\": \"Radiolabeled ATP binding assay; circular dichroism (CD) spectroscopy; thermal stability measurements with purified recombinant C-terminal domain\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro biochemical reconstitution with purified domain, multiple biophysical readouts in single study\",\n      \"pmids\": [\"16686597\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"CLC-5 mutations causing Dent's disease fall into three functional classes: Class 1 mutations cause ER retention and degradation; Class 2 mutations allow normal trafficking but abolish endosomal acidification; Class 3 mutations alter endosomal distribution but preserve acidification. Molecular modeling showed each class maps to discrete structural regions.\",\n      \"method\": \"Electrophysiology; subcellular localization by confocal microscopy; endosomal acidification assay; 3D homology modeling of seven missense mutants\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — multiple orthogonal functional and cell-biological methods on multiple disease mutants, structural modeling in single study\",\n      \"pmids\": [\"19019917\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"CLC-5 interacts with the kinesin motor protein KIF3B via the C-terminus of CLC-5 and the coiled-coil/globular domains of KIF3B; KIF3B overexpression increases and KIF3B siRNA knockdown decreases CLC-5 surface expression and albumin/transferrin endocytosis; CLC-5-containing vesicles move along KIF3B microtubules in live kidney cells.\",\n      \"method\": \"Yeast two-hybrid; GST pull-down; co-immunoprecipitation (including endogenous); confocal live-cell imaging; siRNA knockdown; endocytosis assay\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP plus yeast two-hybrid plus live imaging plus siRNA functional assay, multiple orthogonal methods single lab\",\n      \"pmids\": [\"19940036\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"CLC-5 directly acidifies endosomes by exchanging endosomal Cl- for H+ from the cytoplasm (acting as a Cl-/H+ exchanger), providing a bafilomycin-insensitive component of endosomal acidification; mutations that remove H+ transport (E268A, E211A) abolish this additional acidification. siRNA knockdown of endogenous CLC-5 in proximal tubule cells nearly fully ablated bafilomycin-insensitive acidification.\",\n      \"method\": \"Whole-cell patch clamp; pH-sensitive fluorescent protein targeted to endosomes; site-directed mutagenesis (E268A, E211A); siRNA knockdown; bafilomycin inhibition\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — multiple mutagenesis approaches combined with direct endosomal pH measurement and siRNA validation in single rigorous study\",\n      \"pmids\": [\"20421284\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"ClC-5 PY-motif-dependent ubiquitylation is dispensable for proximal tubular endocytosis in vivo: knock-in mice with a destroyed PY-motif show neither proteinuria nor hyperphosphaturia, and receptor-mediated and fluid-phase endocytosis are normal, contradicting results from heterologous expression systems.\",\n      \"method\": \"PY-motif knock-in mouse; urine protein analysis; endocytosis assays; megalin and NaPi-2a localization by immunohistochemistry\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean knock-in mouse model with definitive negative in vivo phenotype, rigorous controls, directly contradicts heterologous expression studies\",\n      \"pmids\": [\"20351103\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"CLC-5 voltage sensing is an intrinsic property of the protein; permeant anions (particularly Cl-) modulate a voltage-dependent transition to an activated state from which Cl-/H+ exchange occurs. Intracellular Cl- shifts the charge-voltage relationship while lowering intracellular pH does not shift voltage dependence of gating currents.\",\n      \"method\": \"Whole-cell patch clamp of E268A permeation-deficient mutant; gating current recordings; ion substitution experiments\",\n      \"journal\": \"FASEB journal : official publication of the Federation of American Societies for Experimental Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct gating current measurements with structure-function mutagenesis in single rigorous study\",\n      \"pmids\": [\"20501796\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Extracellular protons inhibit CLC-5 by binding to a single site at the extracellular gating glutamate E211, located halfway through the transmembrane electric field, driving the transport cycle in a less permissive direction rather than by reducing driving force.\",\n      \"method\": \"Electrophysiology with varying extracellular pH; SCN- uncoupling experiments to separate H+ and Cl- transport; mechanistic transport cycle modeling\",\n      \"journal\": \"The Journal of general physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — rigorous biophysical dissection using SCN- uncoupling plus pH manipulation, identifying a specific gating mechanism\",\n      \"pmids\": [\"20513761\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"ATP binding induces a conformational change (clamp-like closure) in the isolated C-terminal region of ClC-5, as shown by small-angle X-ray scattering; this conformational compaction promotes biosynthetic maturation and ER exit of full-length ClC-5. Disruption of the ATP-binding site (Y617A) impairs processing and ER trafficking.\",\n      \"method\": \"Small-angle X-ray scattering (SAXS); limited proteolysis; site-directed mutagenesis (Y617A); trafficking assay in fibroblasts and proximal tubule cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — structural SAXS combined with mutagenesis and cell-based trafficking validation in single study\",\n      \"pmids\": [\"21173145\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"ClC-5 is required for exocytic trafficking of NHE3: ClC-5 knockdown reduces basal and dexamethasone-stimulated NHE3 exocytosis (but not endocytosis) in opossum kidney cells, and NHE3 activity is reduced in proximal tubules of Clcn5 KO mice.\",\n      \"method\": \"shRNA knockdown in OK cells; surface biotinylation exocytosis/endocytosis assays; two-photon microscopy of NHE3 activity in Clcn5 KO mice; single tubule perfusion\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA functional data in cell line confirmed with Clcn5 KO mouse, two orthogonal approaches\",\n      \"pmids\": [\"21561868\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"ClC-5 and megalin interact via their C-termini, and this interaction is scaffolded by NHERF2: GST pull-down and co-immunoprecipitation in rat kidney lysate demonstrated the ClC-5/megalin complex; silencing NHERF2 disrupts the megalin/ClC-5 interaction. Fusion protein reconstitution demonstrated a three-protein complex of ClC-5, megalin, and NHERF2.\",\n      \"method\": \"GST pull-down; co-immunoprecipitation from rat kidney lysate; siRNA knockdown of NHERF2; fusion protein reconstitution\",\n      \"journal\": \"The international journal of biochemistry & cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal pull-down plus endogenous co-IP plus in vitro reconstitution, single lab multiple methods\",\n      \"pmids\": [\"22349218\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The proton glutamate E268 of ClC-5 mediates protonation of gating glutamate E211: internal protons increase transport probability of ClC-5 via protonation of E211 at the central anion-binding site, and this effect requires E268. Sulfhydryl modification of E268C mutant confirmed the charge-dependent mechanism.\",\n      \"method\": \"Site-directed mutagenesis (E268H, E268C, E211C, S168P); gating charge measurements; site-directed sulfhydryl modification; electrophysiology\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — rigorous structure-function mutagenesis with multiple complementary mutants and chemical modification in single study\",\n      \"pmids\": [\"22267722\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Disease-causing ClC-5 mutants C221R (membrane domain) and R718X (C-terminal truncation) are misfolded: limited proteolysis shows enhanced protease susceptibility relative to wild-type. C221R disrupts intramolecular interactions affecting the N-terminal cytosolic region; R718X perturbs both C-terminal and membrane domains. Both misfolded mutants are polyubiquitinated and degraded by the proteasome in renal proximal tubule cells.\",\n      \"method\": \"Limited proteolysis; proteasome inhibition assay; polyubiquitination immunoprecipitation in OK cells; protein stability assays\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct biophysical evidence for misfolding combined with cell-based degradation pathway identification in single study\",\n      \"pmids\": [\"23566014\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The gating glutamate E211Q mutation converts ClC-5 from a 2Cl-/H+ exchanger into a pure Cl- channel, which still causes Dent's disease in humans via insufficient V-ATPase activation; both E211A and E211Q stimulate endosomal acidification and V-ATPase activation but less effectively than WT ClC-5, demonstrating functional coupling between V-ATPase and CLC-5.\",\n      \"method\": \"Xenopus oocyte electrophysiology; surface pH measurement; V-ATPase activation assay in HEK293 cells and isolated mouse proximal tubules; gene silencing\",\n      \"journal\": \"Pflugers Archiv : European journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — electrophysiological reconstitution plus direct V-ATPase functional coupling demonstrated in cells and native tissue\",\n      \"pmids\": [\"27044412\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"A novel gating glutamate mutation p.Glu211Gly converts ClC-5 to a Cl- channel (abolishes outward rectification, pH sensitivity, and Cl-/H+ exchange) but does not impair N-glycosylation, plasma membrane localization, or endosomal localization, and does not significantly alter luminal endosomal pH in HEK293T cells, demonstrating that impaired endosomal acidification is not the sole mechanism of Dent's disease.\",\n      \"method\": \"Xenopus oocyte electrophysiology; HEK293T cell expression; N-glycosylation analysis; subcellular localization; pHluorin2 endosomal pH measurement\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — multiple functional and cell-biological assays with direct endosomal pH measurement in single study\",\n      \"pmids\": [\"29791050\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"WT ClC-5 has a 2Cl-/H+ exchange stoichiometry at +40 mV; the S244L variant shows altered stoichiometry (~1.6:1) and reduced Cl-/H+ transport; R345W has slightly higher transport than S244L but is retained in early endosomes; Q629* is retained in ER/cis-Golgi and shows minimal transport. ClC-5 transport is self-inhibitory (provides net negative charges) but facilitates H+-ATPase-mediated endosomal acidification in a burst mode.\",\n      \"method\": \"Ion-selective microelectrodes in Xenopus oocytes; eGFP-tagged protein localization with organelle probes in HEK293 cells; chemiluminescent surface expression assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct stoichiometry measurement plus subcellular trafficking analysis for multiple variants in single study\",\n      \"pmids\": [\"31852738\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"ClC-5 protein is localized to intracellular endosomal compartments (outer medullary endosomes) in the S3 segment of the proximal tubule and medullary thick ascending limb of rat kidney, as established by isoform-specific antiserum and subcellular membrane fractionation.\",\n      \"method\": \"Subcellular membrane fractionation; flow cytometry; immunohistochemistry with isoform-specific antibody; in situ hybridization\",\n      \"journal\": \"The American journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — subcellular fractionation plus immunohistochemistry, confirmed by multiple subsequent studies\",\n      \"pmids\": [\"9815133\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ClC-5 (CLCN5) is an electrogenic 2Cl⁻/1H⁺ exchanger resident in apical endosomes of renal proximal tubule cells, where it facilitates endosomal acidification by providing electrical shunting for the vacuolar H⁺-ATPase and by directly transporting H⁺ into the endosomal lumen; it is essential for both receptor-mediated and fluid-phase endocytosis, regulates surface trafficking of NHE3 (via exocytosis), megalin/cubilin, and NaPi-2, and is regulated by its C-terminal PY-like motif (interacting with WWP2/Nedd4-2 ubiquitin ligases), NHERF2 scaffolding, KIF3B-dependent microtubular transport, and ATP binding to its CBS domains; loss-of-function mutations cause Dent's disease through defective proximal tubular endocytosis with secondary effects on calciotropic hormones, phosphate handling, and vitamin D metabolism.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"CLCN5 (ClC-5) is a member of the CLC family of chloride transport proteins that functions as the principal electrogenic 2Cl⁻/H⁺ exchanger of apical endosomes in the renal proximal tubule, where it is essential for receptor-mediated and fluid-phase endocytosis [#0, #5]. Originally identified by positional cloning as the gene deleted in Dent's disease [#0], ClC-5 was first shown by heterologous expression to carry strongly outwardly rectifying anion currents with a NO3⁻ > Cl⁻ > Br⁻ > I⁻ selectivity, with permeation governed by residues in transmembrane domains D2 and D3 [#1, #3]. ClC-5 resides in early/recycling endosomes alongside the vacuolar H⁺-ATPase, internalized ligands, and Rab markers [#2, #4, #27], where it supports endosomal acidification both by providing an electrical shunt for the V-ATPase and by directly exchanging luminal Cl⁻ for cytoplasmic H⁺, contributing a bafilomycin-insensitive acidification component [#7, #15, #24]. Genetic disruption in mice abolishes apical proximal tubular endocytosis, causing proteinuria, and produces a downstream endocrine cascade in which defective ligand uptake elevates luminal PTH and drives phosphaturia via internalization of NaPi transporters [#5, #7]. Transport mechanism rests on coupled gating glutamates: the gating glutamate E211 senses extracellular protons and is protonated through the proton glutamate E268, coupling H⁺ movement to Cl⁻ exchange [#18, #22]. Surface delivery and trafficking are controlled by ATP binding to the C-terminal CBS domains, which drives a conformational compaction promoting ER exit and biosynthetic maturation [#12, #19], and by C-terminal interactions with the NHERF2 scaffold, megalin, and the kinesin motor KIF3B [#11, #14, #21]. Loss-of-function CLCN5 mutations cause Dent's disease through several distinct mechanisms — ER retention and proteasomal degradation of misfolded protein, defective endosomal targeting, or selective loss of H⁺ coupling that converts ClC-5 into a pure Cl⁻ channel — establishing that impaired endocytosis, not endosomal acidification alone, underlies the disease [#10, #13, #23, #24, #25].\",\n  \"teleology\": [\n    {\n      \"year\": 1994,\n      \"claim\": \"Established CLCN5 as a candidate disease gene by linking a novel kidney-expressed CLC family member to genomic deletion in Dent's disease, defining the gene of interest.\",\n      \"evidence\": \"Positional cloning by YAC/cDNA screening with deletion mapping in patients\",\n      \"pmids\": [\"7874126\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish transport function or subcellular localization\", \"Mechanism linking gene loss to renal phenotype unknown\"]\n    },\n    {\n      \"year\": 1995,\n      \"claim\": \"Demonstrated that ClC-5 carries intrinsic anion current, answering whether it is a functional transport protein and defining its ion selectivity.\",\n      \"evidence\": \"Heterologous expression in Xenopus oocytes with two-electrode voltage clamp\",\n      \"pmids\": [\"8537381\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve whether activity is channel- or exchanger-based\", \"Native subcellular site of activity not addressed\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Placed ClC-5 in endosomal compartments alongside the V-ATPase and endocytosed ligands, establishing the cellular context for its function in renal endocytosis.\",\n      \"evidence\": \"Immunofluorescence colocalization, rab5 mutant cotransfection, and subcellular fractionation in kidney\",\n      \"pmids\": [\"9653142\", \"9815133\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Causal role in acidification not yet tested\", \"Whether ClB-5 is required for endocytosis untested\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Mapped permeation-pathway residues (S168, E211) and confirmed plasma-membrane current, providing the first structure-function link for ion handling.\",\n      \"evidence\": \"Site-directed mutagenesis with two-electrode voltage clamp and HEK293 patch clamp\",\n      \"pmids\": [\"9873029\", \"9931332\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Coupling of anion permeation to proton transport not yet defined\", \"Endosomal versus surface functional roles unresolved\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Demonstrated genetically that ClC-5 is essential for apical proximal tubular endocytosis and for trafficking of apical transporters, establishing the in vivo pathophysiology.\",\n      \"evidence\": \"Clcn5 knockout mouse with endocytosis assays and transporter localization\",\n      \"pmids\": [\"11099045\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism connecting transport activity to endocytic defect unresolved\", \"Direct endosomal pH measurement not yet performed\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Identified a C-terminal PY-like motif controlling surface expression through WWP2-mediated internalization, addressing how ClC-5 trafficking is regulated.\",\n      \"evidence\": \"PY-motif mutagenesis with dominant-negative WWP2 and electrophysiology in oocytes\",\n      \"pmids\": [\"11116157\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological relevance not yet tested in vivo (later contradicted)\", \"Identity of additional ligases not addressed\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Directly confirmed ClC-5's role in endosomal acidification and traced the cascade to PTH-driven phosphaturia, linking transport to systemic phenotype.\",\n      \"evidence\": \"Clcn5 KO mouse endosomal acidification assay with hormone measurements\",\n      \"pmids\": [\"12548389\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether ClC-5 itself transports protons or only shunts charge unresolved\", \"Quantitative contribution to acidification not partitioned\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Showed loss of ClC-5 inverts V-ATPase polarity in patient tubules, indicating a role in maintaining proton-pump distribution.\",\n      \"evidence\": \"Immunohistochemistry of Dent's disease renal biopsies\",\n      \"pmids\": [\"12631345\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, no functional rescue\", \"Causality versus secondary effect not established\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Identified Nedd4-2 as a direct C-terminal ubiquitin-ligase partner regulating ClC-5 surface expression and albumin uptake, expanding the trafficking-regulation network.\",\n      \"evidence\": \"Co-IP, GST pull-down, oocyte electrophysiology, and siRNA albumin uptake assays\",\n      \"pmids\": [\"15489223\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo requirement of ubiquitylation untested (later contradicted)\", \"Relationship to WWP2 pathway unclear\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Demonstrated by rescue that disease mutants fail to restore endocytosis due to defective targeting, mechanistically linking specific mutations to functional loss.\",\n      \"evidence\": \"Adenoviral re-expression of WT and mutant ClC-5 in KO proximal tubule cells with endocytosis and biotinylation assays\",\n      \"pmids\": [\"15942052\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of mistargeting not resolved\", \"Not all mutation classes covered\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Identified NHERF2 (but not NHERF1) as a PDZ-domain scaffold that promotes ClC-5 surface retention and endocytosis, defining a scaffolding control point.\",\n      \"evidence\": \"Co-IP, GST pull-down, and siRNA with surface biotinylation and albumin uptake assays in OK cells\",\n      \"pmids\": [\"16601121\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo relevance not established\", \"Opposing NHERF1/NHERF2 mechanism not fully resolved\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Showed the C-terminal CBS-containing domain directly binds ATP and is stabilized by it, identifying a nucleotide-sensing regulatory module.\",\n      \"evidence\": \"Radiolabeled ATP binding, CD spectroscopy, and thermal stability with purified C-terminal domain\",\n      \"pmids\": [\"16686597\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of ATP binding for the full channel not yet defined\", \"Physiological ATP-sensitivity range untested\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Classified Dent's disease mutations into three functional/structural categories, providing a framework for genotype-mechanism correlation.\",\n      \"evidence\": \"Electrophysiology, confocal localization, acidification assays, and homology modeling of seven mutants\",\n      \"pmids\": [\"19019917\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic structure not available to confirm modeling\", \"Class boundaries based on limited mutant set\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Identified KIF3B as a kinesin motor partner driving microtubule-based trafficking of ClC-5 vesicles, defining the cytoskeletal transport mechanism.\",\n      \"evidence\": \"Yeast two-hybrid, reciprocal co-IP, live-cell imaging, and siRNA endocytosis assays\",\n      \"pmids\": [\"19940036\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo requirement of KIF3B for ClC-5 function untested\", \"Coordination with scaffold/ubiquitin pathways unclear\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Resolved that ClC-5 directly acidifies endosomes as a Cl⁻/H⁺ exchanger, providing a bafilomycin-insensitive acidification component beyond electrical shunting.\",\n      \"evidence\": \"Whole-cell patch clamp, endosome-targeted pH sensors, transport-dead mutagenesis, and siRNA in proximal tubule cells\",\n      \"pmids\": [\"20421284\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative balance of shunt versus direct H⁺ transport not partitioned\", \"Stoichiometry under physiological voltages not yet measured\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Overturned the heterologous-expression model of PY-motif ubiquitylation by showing it is dispensable for endocytosis in vivo, refining the regulatory model.\",\n      \"evidence\": \"PY-motif knock-in mouse with urine, endocytosis, and transporter localization analyses\",\n      \"pmids\": [\"20351103\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Reason for discrepancy with oocyte/cell studies unresolved\", \"Whether ubiquitylation matters under stress conditions untested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Defined intrinsic voltage sensing and anion-coupled gating, and localized extracellular proton inhibition to gating glutamate E211, dissecting the transport cycle.\",\n      \"evidence\": \"Gating-current recordings of permeation-deficient mutant, ion substitution, and SCN⁻ uncoupling with pH manipulation\",\n      \"pmids\": [\"20501796\", \"20513761\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic-resolution gating-state structures not available\", \"Coupling to in-cell endosomal conditions not directly measured\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Showed ATP binding induces clamp-like compaction of the C-terminus that promotes ER exit and maturation, linking nucleotide sensing to biosynthetic trafficking.\",\n      \"evidence\": \"SAXS, limited proteolysis, Y617A mutagenesis, and trafficking assays in fibroblasts and tubule cells\",\n      \"pmids\": [\"21173145\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure of nucleotide-bound full-length protein unresolved\", \"Physiological ATP fluctuations controlling trafficking untested\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Revealed an exocytic role for ClC-5 in NHE3 surface delivery, broadening its function beyond endocytosis.\",\n      \"evidence\": \"shRNA in OK cells with exocytosis/endocytosis biotinylation, plus two-photon NHE3 activity in KO mice\",\n      \"pmids\": [\"21561868\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular link between ClC-5 transport and exocytic machinery unknown\", \"Generality to other exocytosed cargo untested\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Demonstrated a three-protein ClC-5/megalin/NHERF2 complex, mechanistically connecting ClC-5 to the receptor-endocytosis machinery.\",\n      \"evidence\": \"GST pull-down, endogenous co-IP from kidney lysate, NHERF2 siRNA, and fusion-protein reconstitution\",\n      \"pmids\": [\"22349218\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and dynamics of the complex in vivo unresolved\", \"Functional consequence for megalin recycling not directly measured\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Established that proton glutamate E268 mediates protonation of gating glutamate E211, defining the molecular coupling between H⁺ and Cl⁻ transport.\",\n      \"evidence\": \"Charge-coupled mutagenesis, gating-charge measurements, and sulfhydryl modification\",\n      \"pmids\": [\"22267722\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural confirmation of the protonation pathway absent\", \"Behavior at native endosomal pH not directly tested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Showed specific disease mutants are misfolded and proteasomally degraded, defining a degradation-based disease mechanism for membrane and C-terminal mutations.\",\n      \"evidence\": \"Limited proteolysis, proteasome inhibition, and polyubiquitination IP in OK cells\",\n      \"pmids\": [\"23566014\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quality-control machinery recognizing the mutants unidentified\", \"Whether chaperone rescue is feasible untested\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Demonstrated functional coupling between ClC-5 and the V-ATPase, showing a pure-Cl⁻-channel mutant still causes disease via insufficient V-ATPase activation.\",\n      \"evidence\": \"Oocyte electrophysiology, surface pH, and V-ATPase activation assays in cells and native tubules\",\n      \"pmids\": [\"27044412\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of physical/functional V-ATPase coupling unresolved\", \"Relative contribution of H⁺ coupling versus charge shunt in vivo unquantified\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showed a gating-glutamate mutant that preserves trafficking and endosomal pH yet causes disease, establishing that impaired acidification is not the sole disease mechanism.\",\n      \"evidence\": \"Oocyte and HEK293T electrophysiology, glycosylation/localization analysis, and pHluorin2 endosomal pH measurement\",\n      \"pmids\": [\"29791050\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Alternative disease-causing function of Cl⁻/H⁺ exchange unidentified\", \"In vivo phenotype of this variant untested\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Measured native 2Cl⁻/H⁺ stoichiometry and showed variant-specific alterations in transport and trafficking, refining the quantitative transport model.\",\n      \"evidence\": \"Ion-selective microelectrodes in oocytes and organelle-probe localization with surface-expression assays for multiple variants\",\n      \"pmids\": [\"31852738\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Burst-mode acidification model not validated in native endosomes\", \"Variant phenotypes not tested in animal models\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How ClC-5's Cl⁻/H⁺ exchange activity is mechanistically coupled to endocytic and exocytic membrane trafficking — beyond endosomal acidification — remains undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No atomic structure of full-length human ClC-5 in the corpus\", \"Direct molecular link between transport activity and cargo trafficking machinery unresolved\", \"Non-acidification disease mechanism unidentified\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [1, 3, 15, 24, 26]},\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [12, 19]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [2, 4, 15, 27]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [3, 6, 11]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [13, 19, 23]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [5, 14, 20]},\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [1, 15, 24]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [0, 10, 13, 24]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"WWP2\", \"NEDD4L\", \"NHERF2\", \"KIF3B\", \"LRP2\"],\n    \"other_free_text\": []\n  }\n}\n```","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}