{"gene":"CFTR","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":2009,"finding":"VX-770 (ivacaftor) increases CFTR channel open probability (Po) for both F508del and G551D mutant CFTR in recombinant cells, and increases Cl- secretion ~10-fold in cultured human CF bronchial epithelia carrying G551D/F508del, demonstrating pharmacological potentiation of CFTR channel gating.","method":"Patch-clamp electrophysiology in recombinant cells; Ussing chamber Cl- secretion measurements in primary human bronchial epithelial cultures","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct patch-clamp measurement of channel open probability plus functional epithelial secretion assay, multiple orthogonal methods in a rigorous study","pmids":["19846789"],"is_preprint":false},{"year":1999,"finding":"CFTR accounts for the cAMP-regulated chloride conductance of airway epithelial cells; deletion of CFTR causes hyperabsorption of sodium chloride and reduction in periciliary salt and water content, impairing mucociliary clearance.","method":"Electrophysiological studies and airway surface liquid measurements in CF vs. non-CF epithelia; review synthesizing loss-of-function data","journal":"Physiological reviews","confidence":"High","confidence_rationale":"Tier 2 / Strong — extensively replicated across multiple labs using electrophysiology and ion transport measurements in multiple epithelial systems","pmids":["9922383"],"is_preprint":false},{"year":1999,"finding":"F508del-CFTR is synthesized but retained as a core-glycosylated intermediate in the ER due to misfolding; it is recognized by molecular chaperones and rapidly degraded by cytoplasmic proteasomes via multiubiquitination.","method":"Pulse-chase metabolic labeling, proteasome inhibitor experiments, ubiquitination assays; review of biochemical processing data","journal":"Physiological reviews","confidence":"High","confidence_rationale":"Tier 2 / Strong — replicated across multiple labs using biochemical fractionation, proteasome inhibitors, and ubiquitination assays","pmids":["9922380"],"is_preprint":false},{"year":2006,"finding":"CFTR is regulated by both phosphorylation of the R domain and ATP binding/hydrolysis at dual nucleotide-binding sites; only the second NBD is hydrolytic. R domain phosphorylation enables transduction of the nucleotide-binding allosteric signal to the channel gate, but ATP hydrolysis is not required for opening or closing transitions — it clears the ligand-binding site to enable a new gating cycle.","method":"In vitro ATPase assays, patch-clamp electrophysiology, mutagenesis of NBD residues and R domain phosphorylation sites","journal":"Pflugers Archiv : European journal of physiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — biochemical ATPase assays combined with electrophysiology and mutagenesis, replicated across multiple studies","pmids":["17021796"],"is_preprint":false},{"year":2001,"finding":"CFTR chloride channels are regulated by protein kinase A (PKA) as an activator and protein kinase C (PKC) as an enhancer of PKA stimulation; CFTR is also regulated by a membrane-bound protein phosphatase-2C (PP2C) that forms a stable complex with CFTR as shown by co-immunoprecipitation, chemical cross-linking, and pull-down assays.","method":"Patch-clamp electrophysiology, co-immunoprecipitation, chemical cross-linking, pull-down assays","journal":"Pflugers Archiv : European journal of physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple biochemical methods (co-IP, cross-linking, pull-down) from single lab","pmids":["11845311"],"is_preprint":false},{"year":1998,"finding":"CFTR Cl- channels and an associated ATP channel (5.2 pS) are distinct permeation pathways that share common gating machinery dependent on PKA phosphorylation and cytoplasmic ATP/NBD function; gating kinetics of the ATP channel are similarly affected by non-hydrolyzable ATP analogues and mutations in the CFTR R domain and NBDs, but the ATP conduction pathway is not obligatorily linked to CFTR expression.","method":"Single-channel patch-clamp recordings in excised inside-out patches from MDCK cells transiently expressing CFTR, with pharmacological and mutagenesis analysis","journal":"The EMBO journal","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — rigorous single-channel electrophysiology with mutagenesis in a single study","pmids":["9463368"],"is_preprint":false},{"year":2010,"finding":"CFTR is activated by membrane stretch (negative pressures as small as 5 mmHg), increasing both NPo and unitary conductance; this mechanosensitive activation is an intrinsic channel property independent of cytosolic factors and kinase signaling, and results in chloride transport in airway epithelial cells and intestinal tissue.","method":"Single-channel patch-clamp in cell-attached patches with mechanical stimulation; Ussing chamber measurements in Calu-3 cells and mouse intestinal tissue","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — single-channel recordings combined with tissue-level functional assays and multiple orthogonal approaches in one rigorous study","pmids":["20400957"],"is_preprint":false},{"year":2015,"finding":"Tissue-specific knockout of TMEM16A in mouse intestine and airways abolishes not only Ca2+-activated Cl- currents but also CFTR-mediated Cl- secretion; TMEM16A is required for proper activation and membrane expression of CFTR, acting through ER Ca2+ store release engaging Ca2+-regulated adenylyl cyclases.","method":"Tissue-specific gene knockout in mice, Ussing chamber electrophysiology, whole-cell patch-clamp, surface expression assays","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout with multiple electrophysiological and biochemical readouts across two tissue types","pmids":["28963502"],"is_preprint":false},{"year":2006,"finding":"WNK1 co-localizes with CFTR in pulmonary epithelial cells; co-expression of WNK1 or WNK4 with CFTR in Xenopus oocytes suppresses chloride channel activity. WNK4 reduces CFTR protein abundance at the plasma membrane independently of its kinase activity, while WNK1 inhibition of CFTR requires intact kinase activity.","method":"Co-localization by immunofluorescence; Xenopus oocyte expression system with electrophysiology; cell surface biotinylation assays","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional assays in oocytes combined with surface expression measurements and kinase-dead mutant analysis, single lab","pmids":["17194447"],"is_preprint":false},{"year":2019,"finding":"WNK1 kinase domain directly associates with CFTR and increases CFTR bicarbonate permeability (PHCO3/PCl) and conductance; this regulation is [Cl-]i-sensitive. Pancreatitis-causing CFTR mutations R74Q and R75Q in the elbow helix 1 of CFTR impair WNK1-CFTR physical association and reduce WNK1-mediated CFTR HCO3- channel regulation.","method":"Whole-cell, outside-out, and inside-out patch-clamp recordings; molecular dissection with domain deletion constructs; co-immunoprecipitation of WNK1 and CFTR","journal":"Cellular and molecular gastroenterology and hepatology","confidence":"High","confidence_rationale":"Tier 1 / Strong — electrophysiology with domain dissection mutagenesis and co-IP physical interaction data, multiple orthogonal methods","pmids":["31561038"],"is_preprint":false},{"year":2011,"finding":"COMMD1 interacts with CFTR endogenously, protects CFTR from ubiquitination, and promotes CFTR cell surface expression as measured by biotinylation experiments.","method":"Co-immunoprecipitation in cells expressing endogenous proteins; cell surface biotinylation; genetic screen","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal interaction demonstrated endogenously, functional surface expression data, single lab with two orthogonal methods","pmids":["21483833"],"is_preprint":false},{"year":2001,"finding":"Syntaxin 1A (S1A) interacts with CFTR and reduces CFTR channel currents in a syntaxin-isoform-specific manner; S1A inhibits cAMP-regulated CFTR trafficking to the plasma membrane and decreases cell-surface CFTR detected by flag-epitope labeling.","method":"Patch-clamp electrophysiology; membrane capacitance measurements; cell-surface flag-epitope detection by immunofluorescence","journal":"Pflugers Archiv : European journal of physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional channel assays combined with direct surface expression measurements, single lab","pmids":["11845306"],"is_preprint":false},{"year":2004,"finding":"CFTR folding and biosynthetic processing involve molecular chaperones Hsp70/Hdj-1 and calnexin; F508del-CFTR is retained in the ER due to misfolding and degraded by proteasomes, while wild-type CFTR matures through the secretory pathway to the plasma membrane.","method":"Co-immunoprecipitation with chaperones; pulse-chase metabolic labeling; proteasome inhibition experiments; glycosylation analysis","journal":"Journal of molecular neuroscience : MN","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP and biochemical processing assays, replicated across studies","pmids":["15126691"],"is_preprint":false},{"year":2019,"finding":"Hsp70 and co-chaperone DNAJA2 promote CFTR degradation: DNAJA2 overexpression enhances CFTR degradation at the ER via Hsc70/Hsp70 and the E3 ubiquitin ligase CHIP, while excess Hsp70 drives CFTR through lysosomal degradation requiring CHIP but not HOP/Hsp90. Hsp70 inhibitor MKT077 increases mature CFTR levels and enhances ΔF508-CFTR channel activity when combined with corrector VX-809.","method":"Protein overexpression/knockdown; proteasome and lysosome inhibitors; ubiquitination assays; patch-clamp channel activity measurements","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple biochemical and functional assays in single lab, two degradation pathways distinguished with pharmacological tools","pmids":["31408507"],"is_preprint":false},{"year":2015,"finding":"CFTR's gate is located between amino acid residues 337 and 344 along TM6, coinciding with the predicted selectivity filter; cysteines cytoplasmic to this region (positions 344 in TM6, 1148 in TM12) are accessible from both open and closed states, while cysteines external to this region (334, 335, 337) are only accessible from the cytoplasmic side when the channel is open and accessible from the extracellular side when Po is reduced.","method":"Cysteine-scanning mutagenesis with Au(CN)2- as channel-permeant probe; patch-clamp electrophysiology in inside-out and outside-out configurations","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — structure-function mapping with mutagenesis and permeant probe in a rigorous single study with multiple residue substitutions","pmids":["25675504"],"is_preprint":false},{"year":2012,"finding":"CFTR transmembrane domains exhibit alternating access: in the open state the transmembrane pathway faces inwardly (cytoplasm-accessible), while in the closed state it faces outwardly (extracellular-accessible), as demonstrated by state-dependent access of cysteine-reactive probes from both sides of the membrane to introduced cysteines at Leu-102 (TM1) and Thr-338 (TM6).","method":"Cysteine-scanning mutagenesis; MTSES and Au(CN)2- probe access in patch-clamp with gating manipulations via NBD mutations","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — quantitative state-dependent accessibility measurements at two independent positions with two different probes","pmids":["22303012"],"is_preprint":false},{"year":1996,"finding":"The first membrane-spanning domain (TM1-6) of CFTR determines anion permeability sequence and single-channel conductance, as demonstrated by chimeric human-Xenopus CFTR proteins replacing either TM1-6 or TM7-12; the first extracellular loop within TM1-6 influences channel gating.","method":"Chimeric protein construction; whole-cell and single-channel patch-clamp in HeLa cells; site-directed mutagenesis of extracellular loop residues","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — domain-swap chimeras with mutagenesis and direct electrophysiological measurement of permeation and gating properties","pmids":["8810276"],"is_preprint":false},{"year":2014,"finding":"Permeant ions such as nitrate increase CFTR open probability by increasing opening rate and decreasing closing rate, independently of PKA-dependent phosphorylation and NBD dimerization; the effect of nitrate is remarkably similar to VX-770 on single-channel kinetics and deceleration of nonhydrolytic closing, suggesting a shared gating modulation mechanism acting through separate sites.","method":"Single-channel and whole-cell patch-clamp with phosphorylation-independent CFTR constructs and NBD2-deletion constructs; comparison with VX-770 pharmacology","journal":"The Journal of general physiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — patch-clamp with multiple CFTR constructs (phosphorylation-independent, ΔNBD2) and direct comparison of drug vs. ion effects","pmids":["25512598"],"is_preprint":false},{"year":2017,"finding":"CFTR potentiators GLPG1837 and VX-770 share a common mechanism of action: they potentiate CFTR gating independently of NBD dimerization and ATP hydrolysis, compete for the same binding site (shown by combined application), and bind preferentially to the open-channel state (state-dependent binding). GLPG1837 and the ATP analogue dPATP act synergistically through distinct sites.","method":"Single-channel patch-clamp with competitive binding analysis, kinetic modeling, and mutagenesis of NBD residues","journal":"The Journal of general physiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — rigorous single-channel kinetics with competitive inhibition analysis and mechanistic modeling establishing state-dependent binding","pmids":["29079713"],"is_preprint":false},{"year":1994,"finding":"Functional CFTR in endosomal compartments acts as a cAMP-regulated Cl- channel that modulates endosomal Cl- conductance; forskolin increased endosomal pH and dpH/dt (a measure of Cl- conductance) 1.6-fold in CFTR-expressing fibroblasts but not mock-transfected controls.","method":"Quantitative fluorescence image analysis of individual endosomes labeled with carboxyfluorescein-dextran; protonophore-induced pH dissipation assay for endosomal Cl- conductance","journal":"The American journal of physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct measurement of endosomal pH and Cl- conductance in transfected vs. control cells with pharmacological validation","pmids":["7508186"],"is_preprint":false},{"year":2020,"finding":"CFTR amplifiers stabilize CFTR mRNA co-translationally through a mechanism requiring the translated CFTR sequence and translational elongation; amplifiers bind directly to PCBP1 (poly(rC)-binding protein 1) and require a PCBP1 consensus element within the CFTR ORF; amplifiers enrich ER-associated CFTR mRNA and increase its polysome association.","method":"Chemical proteomics pulldown identifying PCBP1 as amplifier-binding protein; polysome profiling; mRNA stability assays; mutagenesis of PCBP1 consensus element in CFTR ORF","journal":"Journal of cystic fibrosis : official journal of the European Cystic Fibrosis Society","confidence":"High","confidence_rationale":"Tier 1 / Strong — chemical proteomics, polysome profiling, mRNA stability, and mutagenesis in a single rigorous multi-method study","pmids":["32067958"],"is_preprint":false},{"year":2018,"finding":"In airway epithelial cells, CFTR compartmentalized signaling requires Ca2+-sensitive adenylyl cyclase type 1 (ADCY1) and exchange protein directly activated by cAMP (EPAC1); activation of Gq/11-coupled GPCRs translocates ADCY1 and EPAC1 to plasma membrane domains containing GPCRs, CFTR, and TMEM16A, enabling crosstalk between Ca2+- and cAMP-dependent signaling. CFTR biosynthesis and membrane trafficking require a functional Golgi apparatus.","method":"GPCR knockdown; co-localization imaging; FRET-based cAMP biosensors; Golgi disruption experiments; electrophysiology","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple signaling and localization assays in single lab establishing compartmentalized CFTR regulation","pmids":["29331508"],"is_preprint":false},{"year":2016,"finding":"In activated human neutrophils, CFTR redistributes from intracellular compartments to the cell surface and to phagosomes; this mobilization correlates with secretory vesicle exocytosis. ΔF508-CF neutrophils fail to mobilize CFTR to phagosomes upon stimulation, resulting in deficient hypochlorous acid production.","method":"Flow cytometry with multiple anti-CFTR antibodies; confocal microscopy of phagosomal targeting; hypochlorous acid production assay in CF vs. normal neutrophils","journal":"Journal of leukocyte biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct subcellular localization tied to functional hypochlorous acid output, multiple antibody controls, comparison of normal vs. CF cells","pmids":["27406994"],"is_preprint":false},{"year":2022,"finding":"Endothelial CFTR loss during S. pneumoniae infection increases intracellular [Cl-], inhibits WNK1, and causes TRPV4-dependent Ca2+ influx leading to vascular barrier failure; ivacaftor prevents CFTR loss and lung edema in infected mice. Mechanistically, the CFTR→WNK1→TRPV4 pathway controls endothelial permeability.","method":"Isolated perfused rat lungs; CFTR inhibitor/activator pharmacology; WNK1 activator/inhibitor experiments; Trpv4-/- mice; intracellular Cl- and Ca2+ measurements; in vivo S. pneumoniae infection model","journal":"Science translational medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple genetic and pharmacological tools, knockout mice, and direct ion measurement across multiple model systems establishing a defined signaling pathway","pmids":["36475904"],"is_preprint":false}],"current_model":"CFTR (ABCC7) is a PKA-phosphorylated, ATP-gated anion (Cl-/HCO3-) channel located at the apical membrane of epithelial cells and endosomes, whose gating requires R-domain phosphorylation to enable allosteric coupling of NBD dimerization/ATP hydrolysis to a gate localized in TM6 (residues 337–344); it is stabilized at the membrane by COMMD1-dependent protection from ubiquitination and regulated by PP2C phosphatase, WNK1 kinase, SNARE protein syntaxin 1A, and TMEM16A, while F508del-CFTR misfolding leads to Hsp70/DNAJA2/CHIP-dependent ER proteasomal and lysosomal degradation; beyond its chloride channel role CFTR also acts as a mechanosensitive channel, regulates ENaC, controls endothelial barrier integrity via a CFTR→WNK1→TRPV4 pathway, and supports neutrophil phagosomal HOCl production."},"narrative":{"mechanistic_narrative":"CFTR is a PKA-phosphorylated, ATP-gated anion channel that provides the cAMP-regulated chloride conductance of epithelial apical membranes, and its loss causes salt/water hyperabsorption that impairs mucociliary clearance [PMID:9922383]. Gating couples R-domain phosphorylation to ATP binding and hydrolysis at two nucleotide-binding domains, of which only the second is hydrolytic; phosphorylation licenses transduction of the nucleotide-binding allosteric signal to the gate, while hydrolysis clears the ligand-binding site to enable a new gating cycle rather than driving opening or closing transitions [PMID:17021796]. The channel gate maps to TM6 residues 337–344 coincident with the selectivity filter, and the permeation pathway alternates access — inwardly facing when open, outwardly facing when closed — with the first membrane-spanning domain (TM1–6) setting anion selectivity and conductance [PMID:25675504, PMID:22303012, PMID:8810276]. Beyond ATP-driven gating, CFTR is intrinsically mechanosensitive, activated by membrane stretch independent of cytosolic factors [PMID:20400957], and conducts bicarbonate under WNK1 control [PMID:31561038]. Channel activity is pharmacologically potentiated by ivacaftor (VX-770) and GLPG1837, which raise open probability by binding the open state at a common site independent of NBD dimerization and hydrolysis, mechanistically paralleling potentiation by permeant anions such as nitrate [PMID:19846789, PMID:25512598, PMID:29079713]. CFTR abundance and surface residency are set by a balance of trafficking and degradation regulators: COMMD1 protects it from ubiquitination [PMID:21483833], syntaxin 1A and WNK kinases suppress surface activity [PMID:17194447, PMID:11845306], and the disease-causing F508del mutant misfolds in the ER and is targeted for proteasomal and lysosomal degradation through Hsp70/DNAJA2/calnexin and the E3 ligase CHIP — the central molecular lesion in cystic fibrosis [PMID:9922380, PMID:15126691, PMID:31408507]. CFTR functions in compartments and cell types beyond apical epithelia, acting as an endosomal Cl- channel [PMID:7508186], cooperating functionally with TMEM16A and Ca2+/cAMP signaling machinery [PMID:28963502, PMID:29331508], supporting neutrophil phagosomal HOCl production [PMID:27406994], and maintaining endothelial barrier integrity via a CFTR→WNK1→TRPV4 pathway [PMID:36475904].","teleology":[{"year":1994,"claim":"Established that CFTR function is not confined to the plasma membrane but operates as a cAMP-regulated Cl- channel in endosomes, broadening its cellular role to organellar ion homeostasis.","evidence":"Quantitative endosomal pH/Cl- conductance fluorescence imaging in CFTR-expressing vs. mock fibroblasts","pmids":["7508186"],"confidence":"Medium","gaps":["Functional consequence of endosomal Cl- conductance for trafficking/acidification not resolved","Whether endosomal pool is the same channel population as apical CFTR unaddressed"]},{"year":1996,"claim":"Mapped which structural region of CFTR encodes its permeation properties, localizing anion selectivity and conductance to the first membrane-spanning domain.","evidence":"Human-Xenopus chimeric CFTR with TM1-6/TM7-12 swaps and extracellular-loop mutagenesis, patch-clamp in HeLa cells","pmids":["8810276"],"confidence":"High","gaps":["Did not resolve atomic pore architecture","Did not identify the gate position within the pathway"]},{"year":1999,"claim":"Defined CFTR as the cAMP-regulated chloride conductance whose loss drives the airway surface liquid defect, linking the molecular channel to cystic fibrosis pathophysiology.","evidence":"Electrophysiology and airway surface liquid measurements in CF vs. non-CF epithelia (review synthesis)","pmids":["9922383"],"confidence":"High","gaps":["Does not address gating mechanism","Relative contribution of ENaC hyperabsorption vs. CFTR loss debated"]},{"year":1999,"claim":"Identified the molecular fate of the most common disease mutation, showing F508del-CFTR misfolds and is degraded rather than mistargeted, defining the ER quality-control lesion in CF.","evidence":"Pulse-chase labeling, proteasome inhibition, ubiquitination assays (review of biochemical processing)","pmids":["9922380"],"confidence":"High","gaps":["Specific chaperones and E3 ligases not yet enumerated here","Lysosomal vs. proteasomal partition not distinguished"]},{"year":2001,"claim":"Established the kinase/phosphatase logic of CFTR regulation, identifying PKA as activator, PKC as enhancer, and a membrane PP2C that forms a stable complex to terminate signaling.","evidence":"Patch-clamp plus co-IP, chemical cross-linking, and pull-down assays","pmids":["11845311"],"confidence":"Medium","gaps":["Single-lab biochemistry","Stoichiometry and structural basis of CFTR-PP2C complex unknown"]},{"year":2001,"claim":"Showed that trafficking partners gate CFTR surface availability, with syntaxin 1A binding CFTR and isoform-specifically reducing its plasma membrane delivery and currents.","evidence":"Patch-clamp, membrane capacitance, and cell-surface flag-epitope detection","pmids":["11845306"],"confidence":"Medium","gaps":["Single lab","Whether interaction is direct vs. mediated unresolved"]},{"year":2006,"claim":"Resolved the energetics of CFTR gating, showing ATP hydrolysis at the single hydrolytic NBD is not required for opening/closing but resets the cycle, with R-domain phosphorylation licensing allosteric coupling.","evidence":"In vitro ATPase assays, patch-clamp, and NBD/R-domain mutagenesis","pmids":["17021796"],"confidence":"High","gaps":["Does not pinpoint the physical gate","Conformational path from NBD to gate not structurally defined"]},{"year":2006,"claim":"Identified WNK kinases as negative regulators of CFTR acting through distinct mechanisms — WNK1 via kinase activity, WNK4 via reduced surface abundance.","evidence":"Immunofluorescence co-localization, Xenopus oocyte electrophysiology, surface biotinylation","pmids":["17194447"],"confidence":"Medium","gaps":["Direct vs. indirect WNK1-CFTR interaction not shown here","Physiological context of inhibition unclear"]},{"year":2010,"claim":"Revealed an intrinsic mechanosensitive mode of CFTR, showing membrane stretch activates the channel independent of kinase signaling and cytosolic factors.","evidence":"Cell-attached single-channel patch-clamp with mechanical stimulation; Ussing chamber in Calu-3 and mouse intestine","pmids":["20400957"],"confidence":"High","gaps":["Structural element sensing stretch unidentified","Physiological stimulus generating stretch in vivo not defined"]},{"year":2011,"claim":"Identified COMMD1 as a stabilizer that protects CFTR from ubiquitination and promotes surface expression, adding a positive arm to CFTR proteostasis.","evidence":"Endogenous co-IP, cell-surface biotinylation, genetic screen","pmids":["21483833"],"confidence":"Medium","gaps":["Which ubiquitin ligase COMMD1 antagonizes not defined","Single lab"]},{"year":2012,"claim":"Demonstrated alternating-access conformational changes in the CFTR transmembrane pathway, with state-dependent probe access establishing an inward-facing open and outward-facing closed configuration.","evidence":"Cysteine-scanning with MTSES/Au(CN)2- probes and gating manipulation via NBD mutations","pmids":["22303012"],"confidence":"High","gaps":["Limited to two reporter positions","Atomic-resolution conformational states not derived"]},{"year":2014,"claim":"Showed permeant anions modulate CFTR gating phosphorylation-independently in a manner mechanistically parallel to VX-770, implying a pore-based gating modulation distinct from the potentiator site.","evidence":"Single-channel/whole-cell patch-clamp with phosphorylation-independent and ΔNBD2 constructs, VX-770 comparison","pmids":["25512598"],"confidence":"High","gaps":["Physical site of nitrate action not mapped","Physiological relevance of anion modulation unclear"]},{"year":2015,"claim":"Localized the CFTR gate to TM6 residues 337–344 coincident with the selectivity filter, unifying gating and permeation at a single structural locus.","evidence":"Cysteine-scanning mutagenesis with Au(CN)2- permeant probe, inside/outside-out patch-clamp","pmids":["25675504"],"confidence":"High","gaps":["Coupling of NBD motions to this gate not structurally traced","Role of other TMs in gating not fully resolved"]},{"year":2015,"claim":"Established a functional dependence of CFTR-mediated secretion on TMEM16A, showing TMEM16A is required for CFTR activation and membrane expression via Ca2+/adenylyl cyclase signaling.","evidence":"Tissue-specific TMEM16A knockout mice, Ussing chamber and whole-cell electrophysiology, surface expression assays","pmids":["28963502"],"confidence":"High","gaps":["Direct physical association vs. signaling crosstalk not distinguished","Tissue generality beyond gut/airway untested"]},{"year":2016,"claim":"Extended CFTR function to innate immunity, showing activated neutrophils mobilize CFTR to phagosomes to enable HOCl production, a step lost in F508del-CF neutrophils.","evidence":"Flow cytometry, confocal phagosomal imaging, HOCl assays in normal vs. CF neutrophils","pmids":["27406994"],"confidence":"Medium","gaps":["Mechanism of CFTR redistribution to phagosomes unknown","Quantitative contribution to bacterial killing not established"]},{"year":2017,"claim":"Defined the pharmacological mechanism of CFTR potentiators, showing VX-770 and GLPG1837 share an open-state-preferring binding site acting independently of NBD dimerization and hydrolysis.","evidence":"Single-channel patch-clamp with competitive binding analysis, kinetic modeling, NBD mutagenesis","pmids":["29079713"],"confidence":"High","gaps":["Structural identity of the potentiator site not resolved here","Synergy mechanism with ATP analogues not mapped to residues"]},{"year":2018,"claim":"Described compartmentalized CFTR signaling, showing GPCR-driven translocation of ADCY1 and EPAC1 into membrane domains containing CFTR and TMEM16A integrates Ca2+ and cAMP control.","evidence":"GPCR knockdown, co-localization, FRET cAMP biosensors, Golgi disruption, electrophysiology","pmids":["29331508"],"confidence":"Medium","gaps":["Single lab","Scaffolding architecture of the signaling domain undefined"]},{"year":2019,"claim":"Identified WNK1 as a direct, [Cl-]i-sensitive regulator of CFTR bicarbonate permeability and linked pancreatitis CFTR mutations (R74Q, R75Q) to disrupted WNK1 association.","evidence":"Whole-cell/outside-out/inside-out patch-clamp, domain-deletion dissection, WNK1-CFTR co-IP","pmids":["31561038"],"confidence":"High","gaps":["Structural basis of elbow-helix-1/WNK1 interface not resolved","How [Cl-]i is sensed mechanistically unclear"]},{"year":2019,"claim":"Dissected the chaperone-driven degradation of F508del-CFTR, distinguishing DNAJA2/Hsc70-CHIP ER proteasomal and Hsp70-driven lysosomal routes and showing Hsp70 inhibition rescues channel activity.","evidence":"Overexpression/knockdown, proteasome/lysosome inhibitors, ubiquitination assays, patch-clamp with VX-809","pmids":["31408507"],"confidence":"Medium","gaps":["Single lab","Relative in vivo contribution of the two degradation routes unknown"]},{"year":2020,"claim":"Defined a co-translational mechanism of CFTR mRNA stabilization by amplifier compounds acting through direct PCBP1 binding to a consensus element in the CFTR ORF.","evidence":"Chemical proteomics, polysome profiling, mRNA stability assays, PCBP1 element mutagenesis","pmids":["32067958"],"confidence":"High","gaps":["Endogenous (drug-free) role of PCBP1 in CFTR expression not established","Structural basis of amplifier-PCBP1-mRNA recognition unknown"]},{"year":2022,"claim":"Established a non-epithelial vascular role for CFTR, defining a CFTR→WNK1→TRPV4 pathway whose loss during infection causes endothelial barrier failure rescued by ivacaftor.","evidence":"Isolated perfused rat lungs, CFTR/WNK1 pharmacology, Trpv4-/- mice, ion measurements, in vivo S. pneumoniae model","pmids":["36475904"],"confidence":"High","gaps":["Molecular trigger of CFTR loss during infection not identified","Generalizability to other infections/inflammatory states untested"]},{"year":null,"claim":"How the NBD dimerization/ATP-hydrolysis cycle is mechanically transmitted to the TM6 gate, and how the potentiator and permeant-anion modulatory sites map onto channel structure, remains unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No atomic-resolution gating-cycle structure in the timeline","Physical location of the VX-770/GLPG1837 site not mapped to residues","Integration of mechanosensitive, anion, and ATP gating inputs unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[1,3,6,14,16,19]},{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[3,5,17]},{"term_id":"GO:0140299","term_label":"molecular sensor activity","supporting_discovery_ids":[6]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[7,23]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,6,11,22]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[19]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[2,12,13,20]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[21]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[22]}],"pathway":[{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[1,3,6,14,16,19]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[2,12,13]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[8,9,21,23]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[0,2,9,23]}],"complexes":[],"partners":["PP2C","WNK1","STX1A","COMMD1","TMEM16A","DNAJA2","HSPA8","PCBP1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P13569","full_name":"Cystic fibrosis transmembrane conductance regulator","aliases":["ATP-binding cassette sub-family C member 7","Channel conductance-controlling ATPase","cAMP-dependent chloride channel"],"length_aa":1480,"mass_kda":168.1,"function":"Epithelial ion channel that plays an important role in the regulation of epithelial ion and water transport and fluid homeostasis (PubMed:26823428). Mediates the transport of chloride ions across the cell membrane (PubMed:10792060, PubMed:11524016, PubMed:11707463, PubMed:12519745, PubMed:12529365, PubMed:12588899, PubMed:12727866, PubMed:15010471, PubMed:17036051, PubMed:1712898, PubMed:17182731, PubMed:19398555, PubMed:19621064, PubMed:22178883, PubMed:25330774, PubMed:26846474, PubMed:28087700, PubMed:8910473, PubMed:9804160). Possesses an intrinsic ATPase activity and utilizes ATP to gate its channel; the passive flow of anions through the channel is gated by cycles of ATP binding and hydrolysis by the ATP-binding domains (PubMed:11524016, PubMed:15284228, PubMed:26627831, PubMed:8910473). The ion channel is also permeable to HCO(3)(-); selectivity depends on the extracellular chloride concentration (PubMed:15010471, PubMed:19019741). In vitro, mediates ATP-dependent glutathione flux (PubMed:12727866). Exerts its function also by modulating the activity of other ion channels and transporters (PubMed:12403779, PubMed:22121115, PubMed:22178883, PubMed:27941075). Plays an important role in airway fluid homeostasis (PubMed:16645176, PubMed:19621064, PubMed:26823428). Contributes to the regulation of the pH and the ion content of the airway surface fluid layer and thereby plays an important role in defense against pathogens (PubMed:14668433, PubMed:16645176, PubMed:26823428). Modulates the activity of the epithelial sodium channel (ENaC) complex, in part by regulating the cell surface expression of the ENaC complex (PubMed:17182731, PubMed:17434346, PubMed:27941075). Inhibits the activity of the ENaC channel containing subunits SCNN1A, SCNN1B and SCNN1G (PubMed:17182731). Inhibits the activity of the ENaC channel containing subunits SCNN1D, SCNN1B and SCNN1G, but not of the ENaC channel containing subunits SCNN1A, SCNN1B and SCNN1G (PubMed:17182731, PubMed:27941075). May regulate bicarbonate secretion and salvage in epithelial cells by regulating the transporter SLC4A7 (PubMed:12403779). Can inhibit the chloride channel activity of ANO1 (PubMed:22178883). Plays a role in the chloride and bicarbonate homeostasis during sperm epididymal maturation and capacitation (PubMed:19923167, PubMed:27714810, PubMed:29393851)","subcellular_location":"Apical cell membrane; Early endosome membrane; Cell membrane; Recycling endosome membrane; Endoplasmic reticulum membrane; Nucleus","url":"https://www.uniprot.org/uniprotkb/P13569/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CFTR","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/CFTR","total_profiled":1310},"omim":[{"mim_id":"620437","title":"TRANSMEMBRANE p24 TRAFFICKING PROTEIN 3; TMED3","url":"https://www.omim.org/entry/620437"},{"mim_id":"620436","title":"TRANSMEMBRANE p24 TRAFFICKING PROTEIN 9; TMED9","url":"https://www.omim.org/entry/620436"},{"mim_id":"620096","title":"RING FINGER PROTEIN 185; RNF185","url":"https://www.omim.org/entry/620096"},{"mim_id":"620045","title":"INTESTINAL DYSMOTILITY SYNDROME; IDMTS","url":"https://www.omim.org/entry/620045"},{"mim_id":"619642","title":"TRANSMEMBRANE p24 TRAFFICKING PROTEIN 2; TMED2","url":"https://www.omim.org/entry/619642"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"gallbladder","ntpm":47.0},{"tissue":"intestine","ntpm":42.2},{"tissue":"pancreas","ntpm":187.0}],"url":"https://www.proteinatlas.org/search/CFTR"},"hgnc":{"alias_symbol":["MRP7","ABC35","TNR-CFTR","dJ760C5.1","CFTR/MRP"],"prev_symbol":["CF","ABCC7"]},"alphafold":{"accession":"P13569","domains":[{"cath_id":"1.20.1560.10","chopping":"42-378_855-888_909-1169","consensus_level":"medium","plddt":87.5206,"start":42,"end":1169},{"cath_id":"3.40.50.300","chopping":"393-408_439-668","consensus_level":"medium","plddt":82.0107,"start":393,"end":668},{"cath_id":"3.40.50.300","chopping":"1211-1443","consensus_level":"high","plddt":82.962,"start":1211,"end":1443}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P13569","model_url":"https://alphafold.ebi.ac.uk/files/AF-P13569-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P13569-F1-predicted_aligned_error_v6.png","plddt_mean":75.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CFTR","jax_strain_url":"https://www.jax.org/strain/search?query=CFTR"},"sequence":{"accession":"P13569","fasta_url":"https://rest.uniprot.org/uniprotkb/P13569.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P13569/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P13569"}},"corpus_meta":[{"pmid":"19846789","id":"PMC_19846789","title":"Rescue 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Cell physiology","url":"https://pubmed.ncbi.nlm.nih.gov/11287314","citation_count":30,"is_preprint":false},{"pmid":"17572159","id":"PMC_17572159","title":"CFTR mutations in the Algerian population.","date":"2007","source":"Journal of cystic fibrosis : official journal of the European Cystic Fibrosis Society","url":"https://pubmed.ncbi.nlm.nih.gov/17572159","citation_count":30,"is_preprint":false},{"pmid":"23331030","id":"PMC_23331030","title":"CFTR inhibitors.","date":"2013","source":"Current pharmaceutical design","url":"https://pubmed.ncbi.nlm.nih.gov/23331030","citation_count":29,"is_preprint":false},{"pmid":"22137130","id":"PMC_22137130","title":"CFTR mutation analysis and haplotype associations in CF patients.","date":"2011","source":"Molecular genetics and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/22137130","citation_count":29,"is_preprint":false},{"pmid":"18782298","id":"PMC_18782298","title":"Identification and characterization of CFTR gene mutations in Indian CF patients.","date":"2008","source":"Annals of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/18782298","citation_count":29,"is_preprint":false},{"pmid":"27704174","id":"PMC_27704174","title":"CFTR pharmacology.","date":"2016","source":"Cellular and molecular life sciences : CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/27704174","citation_count":28,"is_preprint":false},{"pmid":"16798544","id":"PMC_16798544","title":"Atypical CF and CF related diseases.","date":"2006","source":"Paediatric respiratory reviews","url":"https://pubmed.ncbi.nlm.nih.gov/16798544","citation_count":28,"is_preprint":false},{"pmid":"33232302","id":"PMC_33232302","title":"Phenotypes of CF rabbits generated by CRISPR/Cas9-mediated disruption of the CFTR gene.","date":"2021","source":"JCI insight","url":"https://pubmed.ncbi.nlm.nih.gov/33232302","citation_count":28,"is_preprint":false},{"pmid":"31561038","id":"PMC_31561038","title":"Regulation of CFTR Bicarbonate Channel Activity by WNK1: Implications for Pancreatitis and CFTR-Related Disorders.","date":"2019","source":"Cellular and molecular gastroenterology and hepatology","url":"https://pubmed.ncbi.nlm.nih.gov/31561038","citation_count":28,"is_preprint":false},{"pmid":"22303012","id":"PMC_22303012","title":"Alternating access to the transmembrane domain of the ATP-binding cassette protein cystic fibrosis transmembrane conductance regulator (ABCC7).","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22303012","citation_count":28,"is_preprint":false},{"pmid":"25015239","id":"PMC_25015239","title":"Delivery of genes into the CF airway.","date":"2014","source":"Thorax","url":"https://pubmed.ncbi.nlm.nih.gov/25015239","citation_count":27,"is_preprint":false},{"pmid":"15741992","id":"PMC_15741992","title":"Frequency of large CFTR gene rearrangements in Italian CF patients.","date":"2005","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/15741992","citation_count":27,"is_preprint":false},{"pmid":"11845294","id":"PMC_11845294","title":"Cystic fibrosis and CFTR.","date":"2001","source":"Pflugers Archiv : European journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/11845294","citation_count":26,"is_preprint":false},{"pmid":"21039334","id":"PMC_21039334","title":"Targeting CFTR: how to treat cystic fibrosis by CFTR-repairing therapies.","date":"2011","source":"Current drug targets","url":"https://pubmed.ncbi.nlm.nih.gov/21039334","citation_count":26,"is_preprint":false},{"pmid":"15022131","id":"PMC_15022131","title":"NO pathway in CF and non-CF children.","date":"2004","source":"Pediatric pulmonology","url":"https://pubmed.ncbi.nlm.nih.gov/15022131","citation_count":26,"is_preprint":false},{"pmid":"36475904","id":"PMC_36475904","title":"Loss of endothelial CFTR drives barrier failure and edema formation in lung infection and can be targeted by CFTR potentiation.","date":"2022","source":"Science translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/36475904","citation_count":25,"is_preprint":false},{"pmid":"24105369","id":"PMC_24105369","title":"The CF-modifying gene EHF promotes p.Phe508del-CFTR residual function by altering protein glycosylation and trafficking in epithelial cells.","date":"2013","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/24105369","citation_count":25,"is_preprint":false},{"pmid":"31408507","id":"PMC_31408507","title":"Hsp70 and DNAJA2 limit CFTR levels through degradation.","date":"2019","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/31408507","citation_count":25,"is_preprint":false},{"pmid":"27406994","id":"PMC_27406994","title":"CFTR targeting during activation of human neutrophils.","date":"2016","source":"Journal of leukocyte biology","url":"https://pubmed.ncbi.nlm.nih.gov/27406994","citation_count":25,"is_preprint":false},{"pmid":"21547742","id":"PMC_21547742","title":"CFTR Folding Consortium: methods available for studies of CFTR folding and correction.","date":"2011","source":"Methods in molecular biology (Clifton, N.J.)","url":"https://pubmed.ncbi.nlm.nih.gov/21547742","citation_count":25,"is_preprint":false},{"pmid":"24685681","id":"PMC_24685681","title":"Cytoskeleton and CFTR.","date":"2014","source":"The international journal of biochemistry & cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/24685681","citation_count":24,"is_preprint":false},{"pmid":"20607857","id":"PMC_20607857","title":"UMD-CFTR: a database dedicated to CF and CFTR-related disorders.","date":"2010","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/20607857","citation_count":24,"is_preprint":false},{"pmid":"23378603","id":"PMC_23378603","title":"CFTR p.Arg117His associated with CBAVD and other CFTR-related disorders.","date":"2013","source":"Journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/23378603","citation_count":24,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":42849,"output_tokens":6049,"usd":0.109641,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":14784,"output_tokens":6514,"usd":0.118385,"stage2_stop_reason":"end_turn"},"total_usd":0.228026,"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\": 2009,\n      \"finding\": \"VX-770 (ivacaftor) increases CFTR channel open probability (Po) for both F508del and G551D mutant CFTR in recombinant cells, and increases Cl- secretion ~10-fold in cultured human CF bronchial epithelia carrying G551D/F508del, demonstrating pharmacological potentiation of CFTR channel gating.\",\n      \"method\": \"Patch-clamp electrophysiology in recombinant cells; Ussing chamber Cl- secretion measurements in primary human bronchial epithelial cultures\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct patch-clamp measurement of channel open probability plus functional epithelial secretion assay, multiple orthogonal methods in a rigorous study\",\n      \"pmids\": [\"19846789\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"CFTR accounts for the cAMP-regulated chloride conductance of airway epithelial cells; deletion of CFTR causes hyperabsorption of sodium chloride and reduction in periciliary salt and water content, impairing mucociliary clearance.\",\n      \"method\": \"Electrophysiological studies and airway surface liquid measurements in CF vs. non-CF epithelia; review synthesizing loss-of-function data\",\n      \"journal\": \"Physiological reviews\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — extensively replicated across multiple labs using electrophysiology and ion transport measurements in multiple epithelial systems\",\n      \"pmids\": [\"9922383\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"F508del-CFTR is synthesized but retained as a core-glycosylated intermediate in the ER due to misfolding; it is recognized by molecular chaperones and rapidly degraded by cytoplasmic proteasomes via multiubiquitination.\",\n      \"method\": \"Pulse-chase metabolic labeling, proteasome inhibitor experiments, ubiquitination assays; review of biochemical processing data\",\n      \"journal\": \"Physiological reviews\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — replicated across multiple labs using biochemical fractionation, proteasome inhibitors, and ubiquitination assays\",\n      \"pmids\": [\"9922380\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"CFTR is regulated by both phosphorylation of the R domain and ATP binding/hydrolysis at dual nucleotide-binding sites; only the second NBD is hydrolytic. R domain phosphorylation enables transduction of the nucleotide-binding allosteric signal to the channel gate, but ATP hydrolysis is not required for opening or closing transitions — it clears the ligand-binding site to enable a new gating cycle.\",\n      \"method\": \"In vitro ATPase assays, patch-clamp electrophysiology, mutagenesis of NBD residues and R domain phosphorylation sites\",\n      \"journal\": \"Pflugers Archiv : European journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — biochemical ATPase assays combined with electrophysiology and mutagenesis, replicated across multiple studies\",\n      \"pmids\": [\"17021796\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"CFTR chloride channels are regulated by protein kinase A (PKA) as an activator and protein kinase C (PKC) as an enhancer of PKA stimulation; CFTR is also regulated by a membrane-bound protein phosphatase-2C (PP2C) that forms a stable complex with CFTR as shown by co-immunoprecipitation, chemical cross-linking, and pull-down assays.\",\n      \"method\": \"Patch-clamp electrophysiology, co-immunoprecipitation, chemical cross-linking, pull-down assays\",\n      \"journal\": \"Pflugers Archiv : European journal of physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple biochemical methods (co-IP, cross-linking, pull-down) from single lab\",\n      \"pmids\": [\"11845311\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"CFTR Cl- channels and an associated ATP channel (5.2 pS) are distinct permeation pathways that share common gating machinery dependent on PKA phosphorylation and cytoplasmic ATP/NBD function; gating kinetics of the ATP channel are similarly affected by non-hydrolyzable ATP analogues and mutations in the CFTR R domain and NBDs, but the ATP conduction pathway is not obligatorily linked to CFTR expression.\",\n      \"method\": \"Single-channel patch-clamp recordings in excised inside-out patches from MDCK cells transiently expressing CFTR, with pharmacological and mutagenesis analysis\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — rigorous single-channel electrophysiology with mutagenesis in a single study\",\n      \"pmids\": [\"9463368\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"CFTR is activated by membrane stretch (negative pressures as small as 5 mmHg), increasing both NPo and unitary conductance; this mechanosensitive activation is an intrinsic channel property independent of cytosolic factors and kinase signaling, and results in chloride transport in airway epithelial cells and intestinal tissue.\",\n      \"method\": \"Single-channel patch-clamp in cell-attached patches with mechanical stimulation; Ussing chamber measurements in Calu-3 cells and mouse intestinal tissue\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — single-channel recordings combined with tissue-level functional assays and multiple orthogonal approaches in one rigorous study\",\n      \"pmids\": [\"20400957\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Tissue-specific knockout of TMEM16A in mouse intestine and airways abolishes not only Ca2+-activated Cl- currents but also CFTR-mediated Cl- secretion; TMEM16A is required for proper activation and membrane expression of CFTR, acting through ER Ca2+ store release engaging Ca2+-regulated adenylyl cyclases.\",\n      \"method\": \"Tissue-specific gene knockout in mice, Ussing chamber electrophysiology, whole-cell patch-clamp, surface expression assays\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout with multiple electrophysiological and biochemical readouts across two tissue types\",\n      \"pmids\": [\"28963502\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"WNK1 co-localizes with CFTR in pulmonary epithelial cells; co-expression of WNK1 or WNK4 with CFTR in Xenopus oocytes suppresses chloride channel activity. WNK4 reduces CFTR protein abundance at the plasma membrane independently of its kinase activity, while WNK1 inhibition of CFTR requires intact kinase activity.\",\n      \"method\": \"Co-localization by immunofluorescence; Xenopus oocyte expression system with electrophysiology; cell surface biotinylation assays\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional assays in oocytes combined with surface expression measurements and kinase-dead mutant analysis, single lab\",\n      \"pmids\": [\"17194447\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"WNK1 kinase domain directly associates with CFTR and increases CFTR bicarbonate permeability (PHCO3/PCl) and conductance; this regulation is [Cl-]i-sensitive. Pancreatitis-causing CFTR mutations R74Q and R75Q in the elbow helix 1 of CFTR impair WNK1-CFTR physical association and reduce WNK1-mediated CFTR HCO3- channel regulation.\",\n      \"method\": \"Whole-cell, outside-out, and inside-out patch-clamp recordings; molecular dissection with domain deletion constructs; co-immunoprecipitation of WNK1 and CFTR\",\n      \"journal\": \"Cellular and molecular gastroenterology and hepatology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — electrophysiology with domain dissection mutagenesis and co-IP physical interaction data, multiple orthogonal methods\",\n      \"pmids\": [\"31561038\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"COMMD1 interacts with CFTR endogenously, protects CFTR from ubiquitination, and promotes CFTR cell surface expression as measured by biotinylation experiments.\",\n      \"method\": \"Co-immunoprecipitation in cells expressing endogenous proteins; cell surface biotinylation; genetic screen\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal interaction demonstrated endogenously, functional surface expression data, single lab with two orthogonal methods\",\n      \"pmids\": [\"21483833\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Syntaxin 1A (S1A) interacts with CFTR and reduces CFTR channel currents in a syntaxin-isoform-specific manner; S1A inhibits cAMP-regulated CFTR trafficking to the plasma membrane and decreases cell-surface CFTR detected by flag-epitope labeling.\",\n      \"method\": \"Patch-clamp electrophysiology; membrane capacitance measurements; cell-surface flag-epitope detection by immunofluorescence\",\n      \"journal\": \"Pflugers Archiv : European journal of physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional channel assays combined with direct surface expression measurements, single lab\",\n      \"pmids\": [\"11845306\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"CFTR folding and biosynthetic processing involve molecular chaperones Hsp70/Hdj-1 and calnexin; F508del-CFTR is retained in the ER due to misfolding and degraded by proteasomes, while wild-type CFTR matures through the secretory pathway to the plasma membrane.\",\n      \"method\": \"Co-immunoprecipitation with chaperones; pulse-chase metabolic labeling; proteasome inhibition experiments; glycosylation analysis\",\n      \"journal\": \"Journal of molecular neuroscience : MN\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP and biochemical processing assays, replicated across studies\",\n      \"pmids\": [\"15126691\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Hsp70 and co-chaperone DNAJA2 promote CFTR degradation: DNAJA2 overexpression enhances CFTR degradation at the ER via Hsc70/Hsp70 and the E3 ubiquitin ligase CHIP, while excess Hsp70 drives CFTR through lysosomal degradation requiring CHIP but not HOP/Hsp90. Hsp70 inhibitor MKT077 increases mature CFTR levels and enhances ΔF508-CFTR channel activity when combined with corrector VX-809.\",\n      \"method\": \"Protein overexpression/knockdown; proteasome and lysosome inhibitors; ubiquitination assays; patch-clamp channel activity measurements\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple biochemical and functional assays in single lab, two degradation pathways distinguished with pharmacological tools\",\n      \"pmids\": [\"31408507\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"CFTR's gate is located between amino acid residues 337 and 344 along TM6, coinciding with the predicted selectivity filter; cysteines cytoplasmic to this region (positions 344 in TM6, 1148 in TM12) are accessible from both open and closed states, while cysteines external to this region (334, 335, 337) are only accessible from the cytoplasmic side when the channel is open and accessible from the extracellular side when Po is reduced.\",\n      \"method\": \"Cysteine-scanning mutagenesis with Au(CN)2- as channel-permeant probe; patch-clamp electrophysiology in inside-out and outside-out configurations\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — structure-function mapping with mutagenesis and permeant probe in a rigorous single study with multiple residue substitutions\",\n      \"pmids\": [\"25675504\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"CFTR transmembrane domains exhibit alternating access: in the open state the transmembrane pathway faces inwardly (cytoplasm-accessible), while in the closed state it faces outwardly (extracellular-accessible), as demonstrated by state-dependent access of cysteine-reactive probes from both sides of the membrane to introduced cysteines at Leu-102 (TM1) and Thr-338 (TM6).\",\n      \"method\": \"Cysteine-scanning mutagenesis; MTSES and Au(CN)2- probe access in patch-clamp with gating manipulations via NBD mutations\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — quantitative state-dependent accessibility measurements at two independent positions with two different probes\",\n      \"pmids\": [\"22303012\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"The first membrane-spanning domain (TM1-6) of CFTR determines anion permeability sequence and single-channel conductance, as demonstrated by chimeric human-Xenopus CFTR proteins replacing either TM1-6 or TM7-12; the first extracellular loop within TM1-6 influences channel gating.\",\n      \"method\": \"Chimeric protein construction; whole-cell and single-channel patch-clamp in HeLa cells; site-directed mutagenesis of extracellular loop residues\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — domain-swap chimeras with mutagenesis and direct electrophysiological measurement of permeation and gating properties\",\n      \"pmids\": [\"8810276\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Permeant ions such as nitrate increase CFTR open probability by increasing opening rate and decreasing closing rate, independently of PKA-dependent phosphorylation and NBD dimerization; the effect of nitrate is remarkably similar to VX-770 on single-channel kinetics and deceleration of nonhydrolytic closing, suggesting a shared gating modulation mechanism acting through separate sites.\",\n      \"method\": \"Single-channel and whole-cell patch-clamp with phosphorylation-independent CFTR constructs and NBD2-deletion constructs; comparison with VX-770 pharmacology\",\n      \"journal\": \"The Journal of general physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — patch-clamp with multiple CFTR constructs (phosphorylation-independent, ΔNBD2) and direct comparison of drug vs. ion effects\",\n      \"pmids\": [\"25512598\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"CFTR potentiators GLPG1837 and VX-770 share a common mechanism of action: they potentiate CFTR gating independently of NBD dimerization and ATP hydrolysis, compete for the same binding site (shown by combined application), and bind preferentially to the open-channel state (state-dependent binding). GLPG1837 and the ATP analogue dPATP act synergistically through distinct sites.\",\n      \"method\": \"Single-channel patch-clamp with competitive binding analysis, kinetic modeling, and mutagenesis of NBD residues\",\n      \"journal\": \"The Journal of general physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — rigorous single-channel kinetics with competitive inhibition analysis and mechanistic modeling establishing state-dependent binding\",\n      \"pmids\": [\"29079713\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"Functional CFTR in endosomal compartments acts as a cAMP-regulated Cl- channel that modulates endosomal Cl- conductance; forskolin increased endosomal pH and dpH/dt (a measure of Cl- conductance) 1.6-fold in CFTR-expressing fibroblasts but not mock-transfected controls.\",\n      \"method\": \"Quantitative fluorescence image analysis of individual endosomes labeled with carboxyfluorescein-dextran; protonophore-induced pH dissipation assay for endosomal Cl- conductance\",\n      \"journal\": \"The American journal of physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct measurement of endosomal pH and Cl- conductance in transfected vs. control cells with pharmacological validation\",\n      \"pmids\": [\"7508186\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CFTR amplifiers stabilize CFTR mRNA co-translationally through a mechanism requiring the translated CFTR sequence and translational elongation; amplifiers bind directly to PCBP1 (poly(rC)-binding protein 1) and require a PCBP1 consensus element within the CFTR ORF; amplifiers enrich ER-associated CFTR mRNA and increase its polysome association.\",\n      \"method\": \"Chemical proteomics pulldown identifying PCBP1 as amplifier-binding protein; polysome profiling; mRNA stability assays; mutagenesis of PCBP1 consensus element in CFTR ORF\",\n      \"journal\": \"Journal of cystic fibrosis : official journal of the European Cystic Fibrosis Society\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — chemical proteomics, polysome profiling, mRNA stability, and mutagenesis in a single rigorous multi-method study\",\n      \"pmids\": [\"32067958\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"In airway epithelial cells, CFTR compartmentalized signaling requires Ca2+-sensitive adenylyl cyclase type 1 (ADCY1) and exchange protein directly activated by cAMP (EPAC1); activation of Gq/11-coupled GPCRs translocates ADCY1 and EPAC1 to plasma membrane domains containing GPCRs, CFTR, and TMEM16A, enabling crosstalk between Ca2+- and cAMP-dependent signaling. CFTR biosynthesis and membrane trafficking require a functional Golgi apparatus.\",\n      \"method\": \"GPCR knockdown; co-localization imaging; FRET-based cAMP biosensors; Golgi disruption experiments; electrophysiology\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple signaling and localization assays in single lab establishing compartmentalized CFTR regulation\",\n      \"pmids\": [\"29331508\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"In activated human neutrophils, CFTR redistributes from intracellular compartments to the cell surface and to phagosomes; this mobilization correlates with secretory vesicle exocytosis. ΔF508-CF neutrophils fail to mobilize CFTR to phagosomes upon stimulation, resulting in deficient hypochlorous acid production.\",\n      \"method\": \"Flow cytometry with multiple anti-CFTR antibodies; confocal microscopy of phagosomal targeting; hypochlorous acid production assay in CF vs. normal neutrophils\",\n      \"journal\": \"Journal of leukocyte biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct subcellular localization tied to functional hypochlorous acid output, multiple antibody controls, comparison of normal vs. CF cells\",\n      \"pmids\": [\"27406994\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Endothelial CFTR loss during S. pneumoniae infection increases intracellular [Cl-], inhibits WNK1, and causes TRPV4-dependent Ca2+ influx leading to vascular barrier failure; ivacaftor prevents CFTR loss and lung edema in infected mice. Mechanistically, the CFTR→WNK1→TRPV4 pathway controls endothelial permeability.\",\n      \"method\": \"Isolated perfused rat lungs; CFTR inhibitor/activator pharmacology; WNK1 activator/inhibitor experiments; Trpv4-/- mice; intracellular Cl- and Ca2+ measurements; in vivo S. pneumoniae infection model\",\n      \"journal\": \"Science translational medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple genetic and pharmacological tools, knockout mice, and direct ion measurement across multiple model systems establishing a defined signaling pathway\",\n      \"pmids\": [\"36475904\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CFTR (ABCC7) is a PKA-phosphorylated, ATP-gated anion (Cl-/HCO3-) channel located at the apical membrane of epithelial cells and endosomes, whose gating requires R-domain phosphorylation to enable allosteric coupling of NBD dimerization/ATP hydrolysis to a gate localized in TM6 (residues 337–344); it is stabilized at the membrane by COMMD1-dependent protection from ubiquitination and regulated by PP2C phosphatase, WNK1 kinase, SNARE protein syntaxin 1A, and TMEM16A, while F508del-CFTR misfolding leads to Hsp70/DNAJA2/CHIP-dependent ER proteasomal and lysosomal degradation; beyond its chloride channel role CFTR also acts as a mechanosensitive channel, regulates ENaC, controls endothelial barrier integrity via a CFTR→WNK1→TRPV4 pathway, and supports neutrophil phagosomal HOCl production.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CFTR is a PKA-phosphorylated, ATP-gated anion channel that provides the cAMP-regulated chloride conductance of epithelial apical membranes, and its loss causes salt/water hyperabsorption that impairs mucociliary clearance [#1]. Gating couples R-domain phosphorylation to ATP binding and hydrolysis at two nucleotide-binding domains, of which only the second is hydrolytic; phosphorylation licenses transduction of the nucleotide-binding allosteric signal to the gate, while hydrolysis clears the ligand-binding site to enable a new gating cycle rather than driving opening or closing transitions [#3]. The channel gate maps to TM6 residues 337\\u2013344 coincident with the selectivity filter, and the permeation pathway alternates access \\u2014 inwardly facing when open, outwardly facing when closed \\u2014 with the first membrane-spanning domain (TM1\\u20136) setting anion selectivity and conductance [#14, #15, #16]. Beyond ATP-driven gating, CFTR is intrinsically mechanosensitive, activated by membrane stretch independent of cytosolic factors [#6], and conducts bicarbonate under WNK1 control [#9]. Channel activity is pharmacologically potentiated by ivacaftor (VX-770) and GLPG1837, which raise open probability by binding the open state at a common site independent of NBD dimerization and hydrolysis, mechanistically paralleling potentiation by permeant anions such as nitrate [#0, #17, #18]. CFTR abundance and surface residency are set by a balance of trafficking and degradation regulators: COMMD1 protects it from ubiquitination [#10], syntaxin 1A and WNK kinases suppress surface activity [#8, #11], and the disease-causing F508del mutant misfolds in the ER and is targeted for proteasomal and lysosomal degradation through Hsp70/DNAJA2/calnexin and the E3 ligase CHIP \\u2014 the central molecular lesion in cystic fibrosis [#2, #12, #13]. CFTR functions in compartments and cell types beyond apical epithelia, acting as an endosomal Cl- channel [#19], cooperating functionally with TMEM16A and Ca2+/cAMP signaling machinery [#7, #21], supporting neutrophil phagosomal HOCl production [#22], and maintaining endothelial barrier integrity via a CFTR\\u2192WNK1\\u2192TRPV4 pathway [#23].\",\n  \"teleology\": [\n    {\n      \"year\": 1994,\n      \"claim\": \"Established that CFTR function is not confined to the plasma membrane but operates as a cAMP-regulated Cl- channel in endosomes, broadening its cellular role to organellar ion homeostasis.\",\n      \"evidence\": \"Quantitative endosomal pH/Cl- conductance fluorescence imaging in CFTR-expressing vs. mock fibroblasts\",\n      \"pmids\": [\"7508186\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Functional consequence of endosomal Cl- conductance for trafficking/acidification not resolved\", \"Whether endosomal pool is the same channel population as apical CFTR unaddressed\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Mapped which structural region of CFTR encodes its permeation properties, localizing anion selectivity and conductance to the first membrane-spanning domain.\",\n      \"evidence\": \"Human-Xenopus chimeric CFTR with TM1-6/TM7-12 swaps and extracellular-loop mutagenesis, patch-clamp in HeLa cells\",\n      \"pmids\": [\"8810276\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Did not resolve atomic pore architecture\", \"Did not identify the gate position within the pathway\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Defined CFTR as the cAMP-regulated chloride conductance whose loss drives the airway surface liquid defect, linking the molecular channel to cystic fibrosis pathophysiology.\",\n      \"evidence\": \"Electrophysiology and airway surface liquid measurements in CF vs. non-CF epithelia (review synthesis)\",\n      \"pmids\": [\"9922383\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Does not address gating mechanism\", \"Relative contribution of ENaC hyperabsorption vs. CFTR loss debated\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Identified the molecular fate of the most common disease mutation, showing F508del-CFTR misfolds and is degraded rather than mistargeted, defining the ER quality-control lesion in CF.\",\n      \"evidence\": \"Pulse-chase labeling, proteasome inhibition, ubiquitination assays (review of biochemical processing)\",\n      \"pmids\": [\"9922380\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Specific chaperones and E3 ligases not yet enumerated here\", \"Lysosomal vs. proteasomal partition not distinguished\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Established the kinase/phosphatase logic of CFTR regulation, identifying PKA as activator, PKC as enhancer, and a membrane PP2C that forms a stable complex to terminate signaling.\",\n      \"evidence\": \"Patch-clamp plus co-IP, chemical cross-linking, and pull-down assays\",\n      \"pmids\": [\"11845311\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Single-lab biochemistry\", \"Stoichiometry and structural basis of CFTR-PP2C complex unknown\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Showed that trafficking partners gate CFTR surface availability, with syntaxin 1A binding CFTR and isoform-specifically reducing its plasma membrane delivery and currents.\",\n      \"evidence\": \"Patch-clamp, membrane capacitance, and cell-surface flag-epitope detection\",\n      \"pmids\": [\"11845306\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Single lab\", \"Whether interaction is direct vs. mediated unresolved\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Resolved the energetics of CFTR gating, showing ATP hydrolysis at the single hydrolytic NBD is not required for opening/closing but resets the cycle, with R-domain phosphorylation licensing allosteric coupling.\",\n      \"evidence\": \"In vitro ATPase assays, patch-clamp, and NBD/R-domain mutagenesis\",\n      \"pmids\": [\"17021796\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Does not pinpoint the physical gate\", \"Conformational path from NBD to gate not structurally defined\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identified WNK kinases as negative regulators of CFTR acting through distinct mechanisms \\u2014 WNK1 via kinase activity, WNK4 via reduced surface abundance.\",\n      \"evidence\": \"Immunofluorescence co-localization, Xenopus oocyte electrophysiology, surface biotinylation\",\n      \"pmids\": [\"17194447\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Direct vs. indirect WNK1-CFTR interaction not shown here\", \"Physiological context of inhibition unclear\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Revealed an intrinsic mechanosensitive mode of CFTR, showing membrane stretch activates the channel independent of kinase signaling and cytosolic factors.\",\n      \"evidence\": \"Cell-attached single-channel patch-clamp with mechanical stimulation; Ussing chamber in Calu-3 and mouse intestine\",\n      \"pmids\": [\"20400957\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Structural element sensing stretch unidentified\", \"Physiological stimulus generating stretch in vivo not defined\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identified COMMD1 as a stabilizer that protects CFTR from ubiquitination and promotes surface expression, adding a positive arm to CFTR proteostasis.\",\n      \"evidence\": \"Endogenous co-IP, cell-surface biotinylation, genetic screen\",\n      \"pmids\": [\"21483833\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Which ubiquitin ligase COMMD1 antagonizes not defined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Demonstrated alternating-access conformational changes in the CFTR transmembrane pathway, with state-dependent probe access establishing an inward-facing open and outward-facing closed configuration.\",\n      \"evidence\": \"Cysteine-scanning with MTSES/Au(CN)2- probes and gating manipulation via NBD mutations\",\n      \"pmids\": [\"22303012\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Limited to two reporter positions\", \"Atomic-resolution conformational states not derived\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Showed permeant anions modulate CFTR gating phosphorylation-independently in a manner mechanistically parallel to VX-770, implying a pore-based gating modulation distinct from the potentiator site.\",\n      \"evidence\": \"Single-channel/whole-cell patch-clamp with phosphorylation-independent and \\u0394NBD2 constructs, VX-770 comparison\",\n      \"pmids\": [\"25512598\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Physical site of nitrate action not mapped\", \"Physiological relevance of anion modulation unclear\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Localized the CFTR gate to TM6 residues 337\\u2013344 coincident with the selectivity filter, unifying gating and permeation at a single structural locus.\",\n      \"evidence\": \"Cysteine-scanning mutagenesis with Au(CN)2- permeant probe, inside/outside-out patch-clamp\",\n      \"pmids\": [\"25675504\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Coupling of NBD motions to this gate not structurally traced\", \"Role of other TMs in gating not fully resolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Established a functional dependence of CFTR-mediated secretion on TMEM16A, showing TMEM16A is required for CFTR activation and membrane expression via Ca2+/adenylyl cyclase signaling.\",\n      \"evidence\": \"Tissue-specific TMEM16A knockout mice, Ussing chamber and whole-cell electrophysiology, surface expression assays\",\n      \"pmids\": [\"28963502\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Direct physical association vs. signaling crosstalk not distinguished\", \"Tissue generality beyond gut/airway untested\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Extended CFTR function to innate immunity, showing activated neutrophils mobilize CFTR to phagosomes to enable HOCl production, a step lost in F508del-CF neutrophils.\",\n      \"evidence\": \"Flow cytometry, confocal phagosomal imaging, HOCl assays in normal vs. CF neutrophils\",\n      \"pmids\": [\"27406994\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Mechanism of CFTR redistribution to phagosomes unknown\", \"Quantitative contribution to bacterial killing not established\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defined the pharmacological mechanism of CFTR potentiators, showing VX-770 and GLPG1837 share an open-state-preferring binding site acting independently of NBD dimerization and hydrolysis.\",\n      \"evidence\": \"Single-channel patch-clamp with competitive binding analysis, kinetic modeling, NBD mutagenesis\",\n      \"pmids\": [\"29079713\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Structural identity of the potentiator site not resolved here\", \"Synergy mechanism with ATP analogues not mapped to residues\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Described compartmentalized CFTR signaling, showing GPCR-driven translocation of ADCY1 and EPAC1 into membrane domains containing CFTR and TMEM16A integrates Ca2+ and cAMP control.\",\n      \"evidence\": \"GPCR knockdown, co-localization, FRET cAMP biosensors, Golgi disruption, electrophysiology\",\n      \"pmids\": [\"29331508\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Single lab\", \"Scaffolding architecture of the signaling domain undefined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identified WNK1 as a direct, [Cl-]i-sensitive regulator of CFTR bicarbonate permeability and linked pancreatitis CFTR mutations (R74Q, R75Q) to disrupted WNK1 association.\",\n      \"evidence\": \"Whole-cell/outside-out/inside-out patch-clamp, domain-deletion dissection, WNK1-CFTR co-IP\",\n      \"pmids\": [\"31561038\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Structural basis of elbow-helix-1/WNK1 interface not resolved\", \"How [Cl-]i is sensed mechanistically unclear\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Dissected the chaperone-driven degradation of F508del-CFTR, distinguishing DNAJA2/Hsc70-CHIP ER proteasomal and Hsp70-driven lysosomal routes and showing Hsp70 inhibition rescues channel activity.\",\n      \"evidence\": \"Overexpression/knockdown, proteasome/lysosome inhibitors, ubiquitination assays, patch-clamp with VX-809\",\n      \"pmids\": [\"31408507\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Single lab\", \"Relative in vivo contribution of the two degradation routes unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Defined a co-translational mechanism of CFTR mRNA stabilization by amplifier compounds acting through direct PCBP1 binding to a consensus element in the CFTR ORF.\",\n      \"evidence\": \"Chemical proteomics, polysome profiling, mRNA stability assays, PCBP1 element mutagenesis\",\n      \"pmids\": [\"32067958\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Endogenous (drug-free) role of PCBP1 in CFTR expression not established\", \"Structural basis of amplifier-PCBP1-mRNA recognition unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Established a non-epithelial vascular role for CFTR, defining a CFTR\\u2192WNK1\\u2192TRPV4 pathway whose loss during infection causes endothelial barrier failure rescued by ivacaftor.\",\n      \"evidence\": \"Isolated perfused rat lungs, CFTR/WNK1 pharmacology, Trpv4-/- mice, ion measurements, in vivo S. pneumoniae model\",\n      \"pmids\": [\"36475904\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Molecular trigger of CFTR loss during infection not identified\", \"Generalizability to other infections/inflammatory states untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the NBD dimerization/ATP-hydrolysis cycle is mechanically transmitted to the TM6 gate, and how the potentiator and permeant-anion modulatory sites map onto channel structure, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No atomic-resolution gating-cycle structure in the timeline\", \"Physical location of the VX-770/GLPG1837 site not mapped to residues\", \"Integration of mechanosensitive, anion, and ATP gating inputs unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [1, 3, 6, 14, 16, 19]},\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [3, 5, 17]},\n      {\"term_id\": \"GO:0140299\", \"supporting_discovery_ids\": [6]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [7, 23]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 6, 11, 22]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [19]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [2, 12, 13, 20]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [21]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [22]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [1, 3, 6, 14, 16, 19]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [2, 12, 13]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [8, 9, 21, 23]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [0, 2, 9, 23]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"PP2C\", \"WNK1\", \"STX1A\", \"COMMD1\", \"TMEM16A\", \"DNAJA2\", \"HSPA8\", \"PCBP1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}