{"gene":"AGTRAP","run_date":"2026-04-28T17:12:37","timeline":{"discoveries":[{"year":1999,"finding":"ATRAP (AGTRAP) was identified as a novel protein that specifically interacts with the carboxyl-terminal cytoplasmic domain of the AT1a receptor but not with AT2, m3 muscarinic, bradykinin B2, endothelin B, or beta2-adrenergic receptors. Overexpression of ATRAP in COS-7 cells markedly inhibited AT1a receptor-mediated activation of phospholipase C without affecting m3 receptor-mediated activation.","method":"Yeast two-hybrid screening, affinity chromatography, co-immunoprecipitation, fluorescence microscopy, functional PLC activation assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods (Y2H, Co-IP, affinity chromatography, functional assay), foundational paper with 144 citations","pmids":["10358057"],"is_preprint":false},{"year":2000,"finding":"ATRAP potentiates AT1 receptor internalization upon angiotensin II stimulation in vascular smooth muscle cells (VSMCs) and inhibits AT1 receptor-mediated DNA synthesis by suppressing STAT3 and Akt phosphorylation.","method":"Transfection/overexpression in VSMCs, receptor internalization assay, DNA synthesis assay, Western blot for phospho-STAT3 and phospho-Akt","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 — clean overexpression with defined cellular phenotype and signaling readouts, single lab","pmids":["11162453"],"is_preprint":false},{"year":2002,"finding":"Human AGTRAP protein interacts with RACK1 (Receptor of Activated Protein C Kinase), a novel binding partner identified by yeast two-hybrid screening, confirmed by GST pulldown, co-immunoprecipitation, and surface plasmon resonance.","method":"Yeast two-hybrid screening, GST fusion protein pulldown, co-immunoprecipitation, surface plasmon resonance","journal":"The international journal of biochemistry & cell biology","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal binding assays confirming novel interaction, single lab","pmids":["11733189"],"is_preprint":false},{"year":2003,"finding":"ATRAP is a transmembrane protein with three N-terminal hydrophobic domains (residues 14-36, 55-77, 88-108) and a cytoplasmic C-terminal tail (109-161). Its N-terminus faces extracellularly, and it localizes to intracellular trafficking vesicles (ER, Golgi, endocytic vesicles) and plasma membrane, showing constitutive translocation toward the plasma membrane. The C-terminal domain is required for AT1 receptor binding; C-terminal truncation mutants fail to bind AT1R and form perinuclear vesicle clusters. ATRAP overexpression decreases inositol lipid generation, c-fos promoter transcriptional activity, and cell proliferation in response to Ang II.","method":"Epitope-tagged topology analysis, electron microscopy, immunofluorescence, real-time vesicle tracking, mutant analysis, inositol lipid assay, luciferase reporter assay, cell proliferation assay","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods defining topology, localization, and functional domains, 98 citations","pmids":["12960423"],"is_preprint":false},{"year":2005,"finding":"ATRAP overexpression in cardiomyocytes significantly decreases surface AT1R number, reduces p38 MAPK phosphorylation, decreases c-fos promoter activity, and inhibits protein synthesis in response to Ang II, demonstrating that ATRAP promotes AT1R downregulation and attenuates hypertrophic signaling.","method":"Overexpression in cardiomyocytes, surface receptor binding assay, Western blot for phospho-p38 MAPK, luciferase reporter assay, protein synthesis assay","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 — loss-of-function/gain-of-function with multiple defined signaling readouts, single lab","pmids":["15757644"],"is_preprint":false},{"year":2006,"finding":"ATRAP protein co-localizes with the AT1 receptor along renal tubules in vivo (from Bowman's capsules to inner medullary collecting ducts), and dietary salt depletion significantly decreases renal ATRAP expression concomitantly with AT1R expression.","method":"In situ hybridization, Western blot, immunohistochemistry, co-localization analysis in mouse kidney","journal":"Kidney international","confidence":"Medium","confidence_rationale":"Tier 2 — direct in vivo localization with functional regulatory context, multiple methods","pmids":["16514431"],"is_preprint":false},{"year":2010,"finding":"Atrap-deficient (Atrap-/-) mice show increased arterial blood pressure and plasma volume, with enhanced surface AT1 receptor expression in the renal cortex and increased proximal tubular function, establishing that Atrap acts as a negative regulator of AT1 receptors in renal tubules to modulate volume homeostasis.","method":"Knockout mouse model, blood pressure measurement, 125I-AngII binding assay, plasma volume measurement, plasma renin concentration","journal":"Journal of the American Society of Nephrology : JASN","confidence":"High","confidence_rationale":"Tier 2 — genetic KO with multiple orthogonal phenotypic and molecular readouts, replicated across measures","pmids":["20093357"],"is_preprint":false},{"year":2011,"finding":"The PITP domain of RdgBβ (PITPNC1) interacts with ATRAP (AGTRAP), an integral membrane protein, causing membrane recruitment of RdgBβ following PMA treatment. 14-3-3 proteins and ATRAP bind RdgBβ at distinct sites (C-terminus and PITP domain, respectively).","method":"Co-immunoprecipitation, pulldown assays, cell-based membrane recruitment assays","journal":"The Biochemical journal","confidence":"Medium","confidence_rationale":"Tier 2-3 — direct protein-protein interaction confirmed by multiple binding assays, single lab","pmids":["21728994"],"is_preprint":false},{"year":2013,"finding":"Agtrap(-/-) mice under high-fat diet loading display systemic metabolic dysfunction (adipose accumulation, hypertension, dyslipidemia, insulin resistance, adipose tissue inflammation). Subcutaneous transplantation of ATRAP-overexpressing fat pads to Agtrap(-/-) mice improved systemic metabolic dysfunction, demonstrating that adipose ATRAP protects against insulin resistance and metabolic disorders.","method":"Knockout mouse model, high-fat diet challenge, fat pad transplantation rescue experiment, metabolic phenotyping","journal":"Journal of the American Heart Association","confidence":"High","confidence_rationale":"Tier 2 — genetic KO plus rescue transplantation experiment, multiple metabolic phenotypes assessed","pmids":["23902639"],"is_preprint":false},{"year":2014,"finding":"Angiotensin II infusion activates the cardiac proteasome (upregulating β1i, β2i, β5/β5i subunits and increasing proteasome activities), which promotes ATRAP degradation. Proteasome inhibition by bortezomib prevents ATRAP degradation and inactivates AT1R-mediated p38 MAPK and STAT3 signaling, attenuating cardiac hypertrophy.","method":"Ang II infusion mouse model, proteasome inhibitor (bortezomib) treatment, Western blot for ATRAP and signaling molecules, proteasome activity assay","journal":"Journal of molecular and cellular cardiology","confidence":"Medium","confidence_rationale":"Tier 2 — pharmacological intervention with mechanistic pathway placement, single lab","pmids":["25526681"],"is_preprint":false},{"year":2016,"finding":"Atrap directly interacts with the cardiac Ca2+-ATPase SERCA2a, as confirmed by pulldown (MALDI-MS sequencing), co-immunoprecipitation, and surface plasmon resonance. Atrap enhances SERCA-dependent Ca2+ uptake in isolated SR membrane vesicles. Atrap-/- myocytes show prolonged Ca2+ transient decay and sarcomere re-lengthening, and Atrap-/- mice have decreased maximum left ventricular filling rate, demonstrating that Atrap stimulates SERCA2a activity and facilitates ventricular relaxation.","method":"Pulldown with MALDI-MS, co-immunoprecipitation, surface plasmon resonance, Ca2+ uptake assay in SR vesicles, sarcomere shortening and Ca2+ transient measurements in isolated myocytes, echocardiography in Atrap-/- mice","journal":"Cardiovascular research","confidence":"High","confidence_rationale":"Tier 1-2 — reconstitution in SR vesicles, multiple orthogonal binding assays, in vivo KO validation with functional cardiac readouts","pmids":["27015675"],"is_preprint":false},{"year":2019,"finding":"Immunoproteasome subunit β5i (PSMB8) promotes ATRAP degradation via chymotrypsin-like proteasomal activity in Ang II-stimulated atria. β5i knockout markedly restores ATRAP levels, and overexpression of ATRAP reverses β5i-mediated atrial remodeling. Mechanistically, Ang II upregulates β5i to degrade ATRAP, resulting in activation of AT1R-mediated NF-κB signaling, increased NADPH oxidase activity, increased TGF-β1/Smad signaling, and altered Kir2.1 and CX43 expression.","method":"β5i knockout mice, recombinant AAV overexpression of β5i and ATRAP, proteasome activity assays, Western blot for ATRAP and downstream signaling","journal":"Hypertension (Dallas, Tex. : 1979)","confidence":"High","confidence_rationale":"Tier 2 — genetic KO plus gain-of-function AAV with ATRAP rescue, multiple orthogonal molecular readouts, independent replication in retinopathy model","pmids":["30571551"],"is_preprint":false},{"year":2019,"finding":"Ablation of β5i (PSMB8) suppresses Ang II-induced ATRAP degradation in the retina, restoring ATRAP levels and attenuating AT1R downstream signaling. Overexpression of ATRAP abrogated β5i-driven retinopathy, confirming ATRAP degradation by β5i as the mechanistic link.","method":"β5i-KO mice, adenovirus-mediated overexpression of β5i and ATRAP, proteasome activity assays, Western blot","journal":"Molecular therapy : the journal of the American Society of Gene Therapy","confidence":"High","confidence_rationale":"Tier 2 — genetic KO plus viral overexpression with ATRAP rescue, consistent with atrial fibrillation study","pmids":["31636038"],"is_preprint":false},{"year":2019,"finding":"Proximal tubule-specific ATRAP knockout (PT-KO) mice generated via Cre/loxP (Pepck-Cre) show no significant difference in baseline or Ang II-infusion-induced blood pressure or cardiac hypertrophy compared to wild-type mice, indicating that proximal tubule ATRAP has a minor role in angiotensin-dependent hypertension in vivo.","method":"Conditional (proximal tubule-specific) KO mice, radiotelemetric and tail-cuff blood pressure measurement, Ang II infusion","journal":"Journal of the American Heart Association","confidence":"Medium","confidence_rationale":"Tier 2 — cell-type-specific conditional KO with rigorous BP measurement, single lab","pmids":["30977419"],"is_preprint":false},{"year":2021,"finding":"SAM (S-adenosylmethionine) upregulates ATRAP protein expression by methylating HuR, which controls HuR's subcellular localization and its direct binding to ATRAP mRNA, thereby regulating nuclear-cytoplasmic shuttling of ATRAP mRNA and its translation.","method":"HuR methylation assay, RNA immunoprecipitation showing HuR-ATRAP mRNA interaction, subcellular fractionation, gain/loss-of-function in cells and rat NAFLD model","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2-3 — direct RNA-protein interaction demonstrated, PTM-linked mechanism with functional readout, single lab","pmids":["33753727"],"is_preprint":false},{"year":2022,"finding":"In breast cancer cells, ATRAP directs USP14-mediated deubiquitination and stabilization of PBX3, activating the AKT/mTOR signaling pathway to promote cell growth, metastasis, and aerobic glycolysis. USF1 transcriptionally regulates ATRAP expression.","method":"Knockdown/overexpression assays, co-immunoprecipitation for ATRAP-USP14-PBX3 interaction, microarray analysis, functional proliferation/migration assays","journal":"International journal of biological sciences","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP-based interaction with functional cellular assays, single lab, context is cancer rather than canonical AT1R signaling","pmids":["35414770"],"is_preprint":false},{"year":2022,"finding":"DJ-1 (PARK7) in hypoxia-conditioned extracellular vesicles suppresses cardiac hypertrophy by directly interacting with proteasome subunit PSMB10, thereby inhibiting ubiquitin-mediated degradation of ATRAP and downstream AT1R-mediated signaling.","method":"Quantitative proteomics, direct protein interaction assay (DJ-1 vs PSMB10), ubiquitination assay for ATRAP, neonatal rat cardiomyocyte and TAC mouse model","journal":"Pharmacological research","confidence":"Medium","confidence_rationale":"Tier 2-3 — direct physical interaction demonstrated, mechanistic rescue experiment with ATRAP, single lab","pmids":["36509316"],"is_preprint":false},{"year":2023,"finding":"miR-125a-5p and miR-125b-5p directly repress ATRAP/Atrap mRNA, and inhibition of these miRNAs suppresses Ang II-AT1R signaling in mouse distal convoluted tubule cells, establishing miR-125 family members as post-transcriptional regulators of ATRAP.","method":"Luciferase reporter assay for direct miRNA-mRNA targeting, miRNA inhibitor experiments, Ang II-AT1R signaling assays in distal convoluted tubule cells","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 — direct miRNA targeting validated by reporter assay with downstream signaling consequence, single lab","pmids":["37981211"],"is_preprint":false},{"year":2025,"finding":"miR-34a directly targets AGTRAP mRNA in human aortic smooth muscle cells, reducing ATRAP and SIRT1 expression. ATRAP downmodulation further enhances miR-34a expression (negative feedback loop), and Ang II-induced pro-inflammatory gene upregulation (IL-6, COX2, MCP-1, MFGE8) is abolished by forced ATRAP expression.","method":"miR-34a target validation (direct targeting assay), gain/loss-of-function in HASMC, rescue with AGTRAP overexpression, age-associated expression analysis in primate and rodent arteries","journal":"GeroScience","confidence":"Medium","confidence_rationale":"Tier 2-3 — direct targeting with functional rescue, multiple model systems, single lab","pmids":["41291382"],"is_preprint":false},{"year":2026,"finding":"AGTRAP knockdown in glioma cells suppresses IL-6 mRNA/protein levels and attenuates JAK2/STAT3 activation; recombinant IL-6 partially rescues JAK2/STAT3 signaling and growth after AGTRAP silencing, establishing that AGTRAP supports glioma cell survival via an IL-6/JAK2/STAT3 pathway.","method":"siRNA knockdown, proliferation/apoptosis assays, Western blot for JAK2/STAT3 phosphorylation, IL-6 rescue experiment, orthotopic xenograft model","journal":"CNS neuroscience & therapeutics","confidence":"Medium","confidence_rationale":"Tier 2-3 — epistasis via rescue experiment, in vivo validation, single lab","pmids":["41689202"],"is_preprint":false}],"current_model":"AGTRAP (ATRAP) is a three-pass transmembrane protein that binds the carboxyl-terminal cytoplasmic domain of the angiotensin II type 1 receptor (AT1R), promotes constitutive AT1R internalization, and thereby inhibits pathological Ang II-mediated signaling (PLC, p38 MAPK, STAT3, Akt, NF-κB, TGF-β1/Smad); it is also degraded by the immunoproteasome subunit β5i (PSMB8) and regulated post-transcriptionally by miR-125 and miR-34a, and additionally interacts with RACK1 and the Ca2+-ATPase SERCA2a to modulate cardiac Ca2+ handling."},"narrative":{"teleology":[{"year":1999,"claim":"Identification of ATRAP as a specific AT1R-interacting protein resolved how the receptor's cytoplasmic tail could recruit a dedicated regulatory partner distinct from generic GPCR machinery.","evidence":"Yeast two-hybrid, co-IP, affinity chromatography, and PLC activation assay in COS-7 cells","pmids":["10358057"],"confidence":"High","gaps":["Endogenous stoichiometry of ATRAP–AT1R complex unknown","No structural information on the binding interface","Mechanism by which ATRAP inhibits PLC activation not resolved"]},{"year":2000,"claim":"Demonstrating that ATRAP potentiates AT1R internalization and suppresses STAT3/Akt phosphorylation in VSMCs established a receptor-trafficking mechanism for its inhibitory effect on Ang II-driven proliferation.","evidence":"Overexpression in VSMCs with receptor internalization, DNA synthesis, and phospho-STAT3/Akt assays","pmids":["11162453"],"confidence":"Medium","gaps":["Gain-of-function only; endogenous loss-of-function not tested","Internalization mechanism (clathrin, caveolae) not defined"]},{"year":2002,"claim":"Discovery of the ATRAP–RACK1 interaction suggested a scaffold-mediated link between AT1R signaling and PKC pathways, though functional consequence remained undefined.","evidence":"Yeast two-hybrid, GST pulldown, co-IP, and surface plasmon resonance","pmids":["11733189"],"confidence":"Medium","gaps":["Functional consequence of RACK1 interaction on AT1R signaling not tested","Whether RACK1 and AT1R compete for the same ATRAP domain unknown"]},{"year":2003,"claim":"Defining ATRAP as a three-pass transmembrane protein with an extracellular N-terminus and cytoplasmic C-terminal AT1R-binding domain resolved its topology and explained how it traffics constitutively between intracellular vesicles and the plasma membrane.","evidence":"Epitope topology analysis, electron microscopy, immunofluorescence, real-time vesicle tracking, C-terminal truncation mutants","pmids":["12960423"],"confidence":"High","gaps":["No high-resolution structure","Signals mediating constitutive vesicular trafficking not identified"]},{"year":2005,"claim":"Extension to cardiomyocytes showed that ATRAP-mediated AT1R downregulation suppresses p38 MAPK and c-fos activation, positioning ATRAP as an anti-hypertrophic factor in the heart.","evidence":"Overexpression in cardiomyocytes with surface receptor binding, phospho-p38 MAPK, reporter, and protein synthesis assays","pmids":["15757644"],"confidence":"Medium","gaps":["Endogenous cardiomyocyte loss-of-function not yet tested","Whether ATRAP acts on cardiac AT1R specifically or also via SERCA unknown at this stage"]},{"year":2010,"claim":"Agtrap knockout mice established the first in vivo loss-of-function proof that ATRAP is a physiological negative regulator of renal AT1R surface expression, controlling blood pressure and plasma volume homeostasis.","evidence":"Global Agtrap−/− mice with blood pressure telemetry, 125I-AngII binding, plasma volume measurement","pmids":["20093357"],"confidence":"High","gaps":["Tissue-specific contributions not resolved by global KO","Mechanism of increased surface AT1R beyond reduced internalization not clarified"]},{"year":2013,"claim":"Fat-pad transplantation rescue in Agtrap−/− mice on high-fat diet demonstrated that adipose-expressed ATRAP protects against systemic metabolic dysfunction, broadening its role beyond hemodynamics.","evidence":"Global KO with high-fat diet plus subcutaneous fat-pad transplantation rescue, metabolic phenotyping","pmids":["23902639"],"confidence":"High","gaps":["Whether adipose ATRAP acts through AT1R internalization or alternative pathways not distinguished","Contribution of other tissues in the global KO background not excluded"]},{"year":2016,"claim":"Discovery that ATRAP directly binds and stimulates SERCA2a, facilitating Ca²⁺ reuptake and ventricular relaxation, revealed an AT1R-independent cardiac function for ATRAP.","evidence":"Pulldown with MALDI-MS identification, co-IP, SPR, Ca²⁺ uptake in SR vesicles, isolated Atrap−/− myocyte Ca²⁺ transients, echocardiography","pmids":["27015675"],"confidence":"High","gaps":["Binding site on SERCA2a not mapped","Whether ATRAP–SERCA2a interaction is regulated by Ang II unknown","Relative contribution of SERCA2a vs AT1R mechanisms to cardiac phenotype not dissected"]},{"year":2019,"claim":"Identification of β5i (PSMB8)-dependent immunoproteasomal degradation as the principal mechanism controlling ATRAP protein turnover under Ang II stimulation explained how chronic Ang II exposure amplifies its own signaling by eliminating a negative regulator.","evidence":"β5i-KO mice, AAV-mediated overexpression/rescue, proteasome activity assays in atria and retina","pmids":["30571551","31636038"],"confidence":"High","gaps":["Ubiquitin chain type and E3 ligase targeting ATRAP for proteasomal degradation not identified","Whether standard proteasome also degrades ATRAP under basal conditions not resolved"]},{"year":2019,"claim":"Proximal tubule-specific Agtrap deletion did not recapitulate the hypertensive phenotype of global knockouts, indicating that the blood-pressure regulatory function of ATRAP resides outside the proximal tubule.","evidence":"Pepck-Cre conditional KO mice, radiotelemetric and tail-cuff BP measurement under Ang II infusion","pmids":["30977419"],"confidence":"Medium","gaps":["Which nephron segment or non-renal tissue is the critical site remains unknown","Compensatory upregulation in other segments not excluded"]},{"year":2023,"claim":"Validation of miR-125a/b-5p as direct post-transcriptional repressors of ATRAP mRNA in distal convoluted tubule cells established a miRNA-based regulatory layer that modulates Ang II–AT1R signaling in the kidney.","evidence":"Luciferase reporter assay for direct targeting, miRNA inhibitor experiments, Ang II signaling readouts in DCT cells","pmids":["37981211"],"confidence":"Medium","gaps":["In vivo relevance of miR-125 regulation of ATRAP not tested","Whether other miRNAs cooperate not addressed"]},{"year":2025,"claim":"miR-34a directly targets AGTRAP mRNA in vascular smooth muscle, and ATRAP reciprocally suppresses miR-34a, forming a negative feedback loop that links vascular aging and Ang II-induced inflammation.","evidence":"miR-34a target validation, gain/loss-of-function in human aortic SMCs, age-associated expression in primate and rodent arteries","pmids":["41291382"],"confidence":"Medium","gaps":["Mechanism by which ATRAP suppresses miR-34a expression not defined","In vivo miR-34a inhibition to restore ATRAP not performed"]},{"year":null,"claim":"Key unresolved questions include the structural basis of the ATRAP–AT1R and ATRAP–SERCA2a interactions, the identity of the E3 ubiquitin ligase targeting ATRAP for proteasomal degradation, and the specific tissue(s) responsible for ATRAP's blood-pressure regulatory function.","evidence":"","pmids":[],"confidence":"High","gaps":["No high-resolution structure of ATRAP or its complexes","E3 ligase for ATRAP ubiquitination unknown","Critical tissue for blood pressure regulation not pinpointed by conditional KO studies"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,4,6]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,3,10]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[3]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[3]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[3]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[3]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[3]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1,4,6,11]},{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[6,10]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[9,11,12]}],"complexes":[],"partners":["AGTR1","SERCA2A","RACK1","PSMB8","PITPNC1","USP14","PBX3"],"other_free_text":[]},"mechanistic_narrative":"AGTRAP (ATRAP) is a three-pass transmembrane protein that functions as a negative regulator of angiotensin II type 1 receptor (AT1R) signaling by directly binding the AT1R carboxyl-terminal cytoplasmic domain, promoting receptor internalization and downregulation, and thereby attenuating downstream PLC, p38 MAPK, STAT3, Akt, NF-κB, and TGF-β1/Smad signaling cascades [PMID:10358057, PMID:11162453, PMID:15757644, PMID:30571551]. Agtrap-deficient mice exhibit elevated blood pressure, expanded plasma volume, and enhanced surface AT1R expression in the kidney, and under metabolic stress develop systemic insulin resistance and adipose inflammation, establishing AGTRAP as a physiological brake on AT1R-mediated renal and metabolic pathology [PMID:20093357, PMID:23902639]. Independent of its AT1R role, AGTRAP directly interacts with and stimulates the cardiac Ca²⁺-ATPase SERCA2a, facilitating sarcoplasmic reticulum Ca²⁺ reuptake and ventricular relaxation [PMID:27015675]. AGTRAP protein stability is governed by immunoproteasome-mediated degradation through the β5i (PSMB8) subunit, while its mRNA is post-transcriptionally regulated by miR-125a/b-5p and miR-34a [PMID:30571551, PMID:37981211, PMID:41291382]."},"prefetch_data":{"uniprot":{"accession":"Q6RW13","full_name":"Type-1 angiotensin II receptor-associated protein","aliases":["AT1 receptor-associated protein"],"length_aa":159,"mass_kda":17.4,"function":"Appears to be a negative regulator of type-1 angiotensin II receptor-mediated signaling by regulating receptor internalization as well as mechanism of receptor desensitization such as phosphorylation. Also induces a decrease in cell proliferation and angiotensin II-stimulated transcriptional activity","subcellular_location":"Endoplasmic reticulum membrane; Golgi apparatus membrane; Cytoplasmic vesicle membrane","url":"https://www.uniprot.org/uniprotkb/Q6RW13/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/AGTRAP","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000177674","cell_line_id":"CID000074","localizations":[{"compartment":"golgi","grade":3},{"compartment":"vesicles","grade":3},{"compartment":"focal_adhesions","grade":1}],"interactors":[{"gene":"TMEM106B","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000074","total_profiled":1310},"omim":[{"mim_id":"608729","title":"ANGIOTENSIN II RECEPTOR-ASSOCIATED PROTEIN; AGTRAP","url":"https://www.omim.org/entry/608729"},{"mim_id":"601118","title":"CALCIUM-MODULATING LIGAND; CAMLG","url":"https://www.omim.org/entry/601118"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Vesicles","reliability":"Supported"},{"location":"Golgi apparatus","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/AGTRAP"},"hgnc":{"alias_symbol":["ATRAP"],"prev_symbol":[]},"alphafold":{"accession":"Q6RW13","domains":[{"cath_id":"-","chopping":"24-112","consensus_level":"high","plddt":94.5769,"start":24,"end":112}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6RW13","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q6RW13-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q6RW13-F1-predicted_aligned_error_v6.png","plddt_mean":80.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=AGTRAP","jax_strain_url":"https://www.jax.org/strain/search?query=AGTRAP"},"sequence":{"accession":"Q6RW13","fasta_url":"https://rest.uniprot.org/uniprotkb/Q6RW13.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q6RW13/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6RW13"}},"corpus_meta":[{"pmid":"10358057","id":"PMC_10358057","title":"Cloning and characterization of ATRAP, a novel protein that interacts with the angiotensin II type 1 receptor.","date":"1999","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10358057","citation_count":144,"is_preprint":false},{"pmid":"12960423","id":"PMC_12960423","title":"The angiotensin II type I receptor-associated protein, ATRAP, is a transmembrane protein and a modulator of angiotensin II signaling.","date":"2003","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/12960423","citation_count":98,"is_preprint":false},{"pmid":"15757644","id":"PMC_15757644","title":"The novel angiotensin II type 1 receptor (AT1R)-associated protein ATRAP downregulates AT1R and ameliorates cardiomyocyte hypertrophy.","date":"2005","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/15757644","citation_count":75,"is_preprint":false},{"pmid":"11162453","id":"PMC_11162453","title":"ATRAP, novel AT1 receptor associated protein, enhances internalization of AT1 receptor and inhibits vascular smooth muscle cell growth.","date":"2000","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/11162453","citation_count":67,"is_preprint":false},{"pmid":"10572187","id":"PMC_10572187","title":"RET: a poly A-trap retrovirus vector for reversible disruption and expression monitoring of genes in living cells.","date":"1999","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/10572187","citation_count":64,"is_preprint":false},{"pmid":"16514431","id":"PMC_16514431","title":"Interacting molecule of AT1 receptor, ATRAP, is colocalized with AT1 receptor in the mouse renal tubules.","date":"2006","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/16514431","citation_count":56,"is_preprint":false},{"pmid":"30571551","id":"PMC_30571551","title":"Immunoproteasome Subunit β5i Promotes Ang II (Angiotensin II)-Induced Atrial Fibrillation by Targeting ATRAP (Ang II Type I Receptor-Associated Protein) Degradation in Mice.","date":"2019","source":"Hypertension (Dallas, Tex. : 1979)","url":"https://pubmed.ncbi.nlm.nih.gov/30571551","citation_count":55,"is_preprint":false},{"pmid":"25526681","id":"PMC_25526681","title":"Activation of the cardiac proteasome promotes angiotension II-induced hypertrophy by down-regulation of ATRAP.","date":"2014","source":"Journal of molecular and cellular cardiology","url":"https://pubmed.ncbi.nlm.nih.gov/25526681","citation_count":55,"is_preprint":false},{"pmid":"20093357","id":"PMC_20093357","title":"Atrap deficiency increases arterial blood pressure and plasma volume.","date":"2010","source":"Journal of the American Society of Nephrology : JASN","url":"https://pubmed.ncbi.nlm.nih.gov/20093357","citation_count":43,"is_preprint":false},{"pmid":"23902639","id":"PMC_23902639","title":"Angiotensin receptor-binding protein ATRAP/Agtrap inhibits metabolic dysfunction with visceral obesity.","date":"2013","source":"Journal of the American Heart Association","url":"https://pubmed.ncbi.nlm.nih.gov/23902639","citation_count":38,"is_preprint":false},{"pmid":"23176217","id":"PMC_23176217","title":"The physiology and pathophysiology of a novel angiotensin receptor-binding protein ATRAP/Agtrap.","date":"2013","source":"Current pharmaceutical design","url":"https://pubmed.ncbi.nlm.nih.gov/23176217","citation_count":34,"is_preprint":false},{"pmid":"11733189","id":"PMC_11733189","title":"Identification and characterization of AGTRAP, a human homolog of murine Angiotensin II Receptor-Associated Protein (Agtrap).","date":"2002","source":"The international journal of biochemistry & cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/11733189","citation_count":31,"is_preprint":false},{"pmid":"31636038","id":"PMC_31636038","title":"Ablation of Immunoproteasome β5i Subunit Suppresses Hypertensive Retinopathy by Blocking ATRAP Degradation in Mice.","date":"2019","source":"Molecular therapy : the journal of the American Society of Gene Therapy","url":"https://pubmed.ncbi.nlm.nih.gov/31636038","citation_count":30,"is_preprint":false},{"pmid":"21728994","id":"PMC_21728994","title":"The phosphatidylinositol transfer protein RdgBβ binds 14-3-3 via its unstructured C-terminus, whereas its lipid-binding domain interacts with the integral membrane protein ATRAP (angiotensin II type I receptor-associated protein).","date":"2011","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/21728994","citation_count":27,"is_preprint":false},{"pmid":"33753727","id":"PMC_33753727","title":"S-adenosylmethionine upregulates the angiotensin receptor-binding protein ATRAP via the methylation of HuR in NAFLD.","date":"2021","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/33753727","citation_count":26,"is_preprint":false},{"pmid":"36509316","id":"PMC_36509316","title":"Extracellular vesicles DJ-1 derived from hypoxia-conditioned hMSCs alleviate cardiac hypertrophy by suppressing mitochondria 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streptozotocin-induced diabetic glomerular injury via reducing protective macrophage polarization.","date":"2022","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/35240129","citation_count":22,"is_preprint":false},{"pmid":"34642449","id":"PMC_34642449","title":"ATRAP, a receptor-interacting modulator of kidney physiology, as a novel player in blood pressure and beyond.","date":"2021","source":"Hypertension research : official journal of the Japanese Society of Hypertension","url":"https://pubmed.ncbi.nlm.nih.gov/34642449","citation_count":20,"is_preprint":false},{"pmid":"29257219","id":"PMC_29257219","title":"Effect of prehypertensive losartan therapy on AT1R and ATRAP methylation of adipose tissue in the later life of high‑fat‑fed spontaneously hypertensive rats.","date":"2017","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/29257219","citation_count":17,"is_preprint":false},{"pmid":"26295465","id":"PMC_26295465","title":"Angiotensin II Type 1 Receptor Binding Molecule ATRAP as a Possible Modulator of Renal Sodium Handling and Blood Pressure in Pathophysiology.","date":"2015","source":"Current medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/26295465","citation_count":14,"is_preprint":false},{"pmid":"28656601","id":"PMC_28656601","title":"Silencing of AtRAP, a target gene of a bacteria-induced small RNA, triggers antibacterial defense responses through activation of LSU2 and down-regulation of GLK1.","date":"2017","source":"The New phytologist","url":"https://pubmed.ncbi.nlm.nih.gov/28656601","citation_count":14,"is_preprint":false},{"pmid":"27015675","id":"PMC_27015675","title":"The angiotensin receptor-associated protein Atrap is a stimulator of the cardiac Ca2+-ATPase SERCA2a.","date":"2016","source":"Cardiovascular research","url":"https://pubmed.ncbi.nlm.nih.gov/27015675","citation_count":12,"is_preprint":false},{"pmid":"30977419","id":"PMC_30977419","title":"Effects of ATRAP in Renal Proximal Tubules on Angiotensin-Dependent Hypertension.","date":"2019","source":"Journal of the American Heart Association","url":"https://pubmed.ncbi.nlm.nih.gov/30977419","citation_count":11,"is_preprint":false},{"pmid":"22435829","id":"PMC_22435829","title":"14-3-3 protein and ATRAP bind to the soluble class IIB phosphatidylinositol transfer protein RdgBβ at distinct sites.","date":"2012","source":"Biochemical Society transactions","url":"https://pubmed.ncbi.nlm.nih.gov/22435829","citation_count":10,"is_preprint":false},{"pmid":"28335584","id":"PMC_28335584","title":"ATRAP Expression in Brown Adipose Tissue Does Not Influence the Development of Diet-Induced Metabolic Disorders in Mice.","date":"2017","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/28335584","citation_count":10,"is_preprint":false},{"pmid":"35710020","id":"PMC_35710020","title":"Melatonin inhibits angiotensin II-induced atrial fibrillation through preventing degradation of Ang II 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Stratification System Based on AGTRAP in Patients with Hepatocellular Carcinoma.","date":"2021","source":"Disease markers","url":"https://pubmed.ncbi.nlm.nih.gov/34840632","citation_count":6,"is_preprint":false},{"pmid":"35927940","id":"PMC_35927940","title":"Modulation of blood pressure regulatory genes in the Agtrap-Plod1 locus associated with a deletion in Clcn6.","date":"2022","source":"Physiological reports","url":"https://pubmed.ncbi.nlm.nih.gov/35927940","citation_count":4,"is_preprint":false},{"pmid":"28000857","id":"PMC_28000857","title":"Hypomethylation of Agtrap is associated with long-term inhibition of left ventricular hypertrophy in prehypertensive losartan-treated spontaneously hypertensive rats.","date":"2016","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/28000857","citation_count":4,"is_preprint":false},{"pmid":"23012794","id":"PMC_23012794","title":"[Physiology of novel AT1 receptor-binding molecule, ATRAP].","date":"2012","source":"Nihon rinsho. Japanese journal of clinical medicine","url":"https://pubmed.ncbi.nlm.nih.gov/23012794","citation_count":1,"is_preprint":false},{"pmid":"41689202","id":"PMC_41689202","title":"Angiotensin II Receptor-Associated Protein (AGTRAP) Enhances Glioma Cell Survival Through the IL-6/JAK2/STAT3 Pathway and Correlates With an Immunosuppressive Microenvironment.","date":"2026","source":"CNS neuroscience & therapeutics","url":"https://pubmed.ncbi.nlm.nih.gov/41689202","citation_count":1,"is_preprint":false},{"pmid":"41291382","id":"PMC_41291382","title":"Angiotensin II, miR-34a, and AGTRAP crosstalk in arterial smooth muscle cells.","date":"2025","source":"GeroScience","url":"https://pubmed.ncbi.nlm.nih.gov/41291382","citation_count":0,"is_preprint":false},{"pmid":"40721451","id":"PMC_40721451","title":"Effects of proximal tubule-specific ATRAP enhancement on hypertension in a remnant kidney chronic kidney disease model of mice.","date":"2025","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/40721451","citation_count":0,"is_preprint":false},{"pmid":"40865403","id":"PMC_40865403","title":"Lentinan ameliorates angiotensin II-induced hypertension-associated intestinal barrier injury through inactivation of PSMB8-ATRAP signaling.","date":"2025","source":"International immunopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/40865403","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":20908,"output_tokens":5004,"usd":0.068892},"stage2":{"model":"claude-opus-4-6","input_tokens":8561,"output_tokens":3061,"usd":0.178995},"total_usd":0.247887,"stage1_batch_id":"msgbatch_01TqNM6p6FsoMBT2jzQTwKBr","stage2_batch_id":"msgbatch_01Ya473eco8sTHbvRymQaU8o","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1999,\n      \"finding\": \"ATRAP (AGTRAP) was identified as a novel protein that specifically interacts with the carboxyl-terminal cytoplasmic domain of the AT1a receptor but not with AT2, m3 muscarinic, bradykinin B2, endothelin B, or beta2-adrenergic receptors. Overexpression of ATRAP in COS-7 cells markedly inhibited AT1a receptor-mediated activation of phospholipase C without affecting m3 receptor-mediated activation.\",\n      \"method\": \"Yeast two-hybrid screening, affinity chromatography, co-immunoprecipitation, fluorescence microscopy, functional PLC activation assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods (Y2H, Co-IP, affinity chromatography, functional assay), foundational paper with 144 citations\",\n      \"pmids\": [\"10358057\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"ATRAP potentiates AT1 receptor internalization upon angiotensin II stimulation in vascular smooth muscle cells (VSMCs) and inhibits AT1 receptor-mediated DNA synthesis by suppressing STAT3 and Akt phosphorylation.\",\n      \"method\": \"Transfection/overexpression in VSMCs, receptor internalization assay, DNA synthesis assay, Western blot for phospho-STAT3 and phospho-Akt\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean overexpression with defined cellular phenotype and signaling readouts, single lab\",\n      \"pmids\": [\"11162453\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Human AGTRAP protein interacts with RACK1 (Receptor of Activated Protein C Kinase), a novel binding partner identified by yeast two-hybrid screening, confirmed by GST pulldown, co-immunoprecipitation, and surface plasmon resonance.\",\n      \"method\": \"Yeast two-hybrid screening, GST fusion protein pulldown, co-immunoprecipitation, surface plasmon resonance\",\n      \"journal\": \"The international journal of biochemistry & cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal binding assays confirming novel interaction, single lab\",\n      \"pmids\": [\"11733189\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"ATRAP is a transmembrane protein with three N-terminal hydrophobic domains (residues 14-36, 55-77, 88-108) and a cytoplasmic C-terminal tail (109-161). Its N-terminus faces extracellularly, and it localizes to intracellular trafficking vesicles (ER, Golgi, endocytic vesicles) and plasma membrane, showing constitutive translocation toward the plasma membrane. The C-terminal domain is required for AT1 receptor binding; C-terminal truncation mutants fail to bind AT1R and form perinuclear vesicle clusters. ATRAP overexpression decreases inositol lipid generation, c-fos promoter transcriptional activity, and cell proliferation in response to Ang II.\",\n      \"method\": \"Epitope-tagged topology analysis, electron microscopy, immunofluorescence, real-time vesicle tracking, mutant analysis, inositol lipid assay, luciferase reporter assay, cell proliferation assay\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods defining topology, localization, and functional domains, 98 citations\",\n      \"pmids\": [\"12960423\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"ATRAP overexpression in cardiomyocytes significantly decreases surface AT1R number, reduces p38 MAPK phosphorylation, decreases c-fos promoter activity, and inhibits protein synthesis in response to Ang II, demonstrating that ATRAP promotes AT1R downregulation and attenuates hypertrophic signaling.\",\n      \"method\": \"Overexpression in cardiomyocytes, surface receptor binding assay, Western blot for phospho-p38 MAPK, luciferase reporter assay, protein synthesis assay\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — loss-of-function/gain-of-function with multiple defined signaling readouts, single lab\",\n      \"pmids\": [\"15757644\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"ATRAP protein co-localizes with the AT1 receptor along renal tubules in vivo (from Bowman's capsules to inner medullary collecting ducts), and dietary salt depletion significantly decreases renal ATRAP expression concomitantly with AT1R expression.\",\n      \"method\": \"In situ hybridization, Western blot, immunohistochemistry, co-localization analysis in mouse kidney\",\n      \"journal\": \"Kidney international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct in vivo localization with functional regulatory context, multiple methods\",\n      \"pmids\": [\"16514431\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Atrap-deficient (Atrap-/-) mice show increased arterial blood pressure and plasma volume, with enhanced surface AT1 receptor expression in the renal cortex and increased proximal tubular function, establishing that Atrap acts as a negative regulator of AT1 receptors in renal tubules to modulate volume homeostasis.\",\n      \"method\": \"Knockout mouse model, blood pressure measurement, 125I-AngII binding assay, plasma volume measurement, plasma renin concentration\",\n      \"journal\": \"Journal of the American Society of Nephrology : JASN\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with multiple orthogonal phenotypic and molecular readouts, replicated across measures\",\n      \"pmids\": [\"20093357\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The PITP domain of RdgBβ (PITPNC1) interacts with ATRAP (AGTRAP), an integral membrane protein, causing membrane recruitment of RdgBβ following PMA treatment. 14-3-3 proteins and ATRAP bind RdgBβ at distinct sites (C-terminus and PITP domain, respectively).\",\n      \"method\": \"Co-immunoprecipitation, pulldown assays, cell-based membrane recruitment assays\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — direct protein-protein interaction confirmed by multiple binding assays, single lab\",\n      \"pmids\": [\"21728994\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Agtrap(-/-) mice under high-fat diet loading display systemic metabolic dysfunction (adipose accumulation, hypertension, dyslipidemia, insulin resistance, adipose tissue inflammation). Subcutaneous transplantation of ATRAP-overexpressing fat pads to Agtrap(-/-) mice improved systemic metabolic dysfunction, demonstrating that adipose ATRAP protects against insulin resistance and metabolic disorders.\",\n      \"method\": \"Knockout mouse model, high-fat diet challenge, fat pad transplantation rescue experiment, metabolic phenotyping\",\n      \"journal\": \"Journal of the American Heart Association\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO plus rescue transplantation experiment, multiple metabolic phenotypes assessed\",\n      \"pmids\": [\"23902639\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Angiotensin II infusion activates the cardiac proteasome (upregulating β1i, β2i, β5/β5i subunits and increasing proteasome activities), which promotes ATRAP degradation. Proteasome inhibition by bortezomib prevents ATRAP degradation and inactivates AT1R-mediated p38 MAPK and STAT3 signaling, attenuating cardiac hypertrophy.\",\n      \"method\": \"Ang II infusion mouse model, proteasome inhibitor (bortezomib) treatment, Western blot for ATRAP and signaling molecules, proteasome activity assay\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — pharmacological intervention with mechanistic pathway placement, single lab\",\n      \"pmids\": [\"25526681\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Atrap directly interacts with the cardiac Ca2+-ATPase SERCA2a, as confirmed by pulldown (MALDI-MS sequencing), co-immunoprecipitation, and surface plasmon resonance. Atrap enhances SERCA-dependent Ca2+ uptake in isolated SR membrane vesicles. Atrap-/- myocytes show prolonged Ca2+ transient decay and sarcomere re-lengthening, and Atrap-/- mice have decreased maximum left ventricular filling rate, demonstrating that Atrap stimulates SERCA2a activity and facilitates ventricular relaxation.\",\n      \"method\": \"Pulldown with MALDI-MS, co-immunoprecipitation, surface plasmon resonance, Ca2+ uptake assay in SR vesicles, sarcomere shortening and Ca2+ transient measurements in isolated myocytes, echocardiography in Atrap-/- mice\",\n      \"journal\": \"Cardiovascular research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — reconstitution in SR vesicles, multiple orthogonal binding assays, in vivo KO validation with functional cardiac readouts\",\n      \"pmids\": [\"27015675\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Immunoproteasome subunit β5i (PSMB8) promotes ATRAP degradation via chymotrypsin-like proteasomal activity in Ang II-stimulated atria. β5i knockout markedly restores ATRAP levels, and overexpression of ATRAP reverses β5i-mediated atrial remodeling. Mechanistically, Ang II upregulates β5i to degrade ATRAP, resulting in activation of AT1R-mediated NF-κB signaling, increased NADPH oxidase activity, increased TGF-β1/Smad signaling, and altered Kir2.1 and CX43 expression.\",\n      \"method\": \"β5i knockout mice, recombinant AAV overexpression of β5i and ATRAP, proteasome activity assays, Western blot for ATRAP and downstream signaling\",\n      \"journal\": \"Hypertension (Dallas, Tex. : 1979)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO plus gain-of-function AAV with ATRAP rescue, multiple orthogonal molecular readouts, independent replication in retinopathy model\",\n      \"pmids\": [\"30571551\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Ablation of β5i (PSMB8) suppresses Ang II-induced ATRAP degradation in the retina, restoring ATRAP levels and attenuating AT1R downstream signaling. Overexpression of ATRAP abrogated β5i-driven retinopathy, confirming ATRAP degradation by β5i as the mechanistic link.\",\n      \"method\": \"β5i-KO mice, adenovirus-mediated overexpression of β5i and ATRAP, proteasome activity assays, Western blot\",\n      \"journal\": \"Molecular therapy : the journal of the American Society of Gene Therapy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO plus viral overexpression with ATRAP rescue, consistent with atrial fibrillation study\",\n      \"pmids\": [\"31636038\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Proximal tubule-specific ATRAP knockout (PT-KO) mice generated via Cre/loxP (Pepck-Cre) show no significant difference in baseline or Ang II-infusion-induced blood pressure or cardiac hypertrophy compared to wild-type mice, indicating that proximal tubule ATRAP has a minor role in angiotensin-dependent hypertension in vivo.\",\n      \"method\": \"Conditional (proximal tubule-specific) KO mice, radiotelemetric and tail-cuff blood pressure measurement, Ang II infusion\",\n      \"journal\": \"Journal of the American Heart Association\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — cell-type-specific conditional KO with rigorous BP measurement, single lab\",\n      \"pmids\": [\"30977419\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"SAM (S-adenosylmethionine) upregulates ATRAP protein expression by methylating HuR, which controls HuR's subcellular localization and its direct binding to ATRAP mRNA, thereby regulating nuclear-cytoplasmic shuttling of ATRAP mRNA and its translation.\",\n      \"method\": \"HuR methylation assay, RNA immunoprecipitation showing HuR-ATRAP mRNA interaction, subcellular fractionation, gain/loss-of-function in cells and rat NAFLD model\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — direct RNA-protein interaction demonstrated, PTM-linked mechanism with functional readout, single lab\",\n      \"pmids\": [\"33753727\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"In breast cancer cells, ATRAP directs USP14-mediated deubiquitination and stabilization of PBX3, activating the AKT/mTOR signaling pathway to promote cell growth, metastasis, and aerobic glycolysis. USF1 transcriptionally regulates ATRAP expression.\",\n      \"method\": \"Knockdown/overexpression assays, co-immunoprecipitation for ATRAP-USP14-PBX3 interaction, microarray analysis, functional proliferation/migration assays\",\n      \"journal\": \"International journal of biological sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP-based interaction with functional cellular assays, single lab, context is cancer rather than canonical AT1R signaling\",\n      \"pmids\": [\"35414770\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"DJ-1 (PARK7) in hypoxia-conditioned extracellular vesicles suppresses cardiac hypertrophy by directly interacting with proteasome subunit PSMB10, thereby inhibiting ubiquitin-mediated degradation of ATRAP and downstream AT1R-mediated signaling.\",\n      \"method\": \"Quantitative proteomics, direct protein interaction assay (DJ-1 vs PSMB10), ubiquitination assay for ATRAP, neonatal rat cardiomyocyte and TAC mouse model\",\n      \"journal\": \"Pharmacological research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — direct physical interaction demonstrated, mechanistic rescue experiment with ATRAP, single lab\",\n      \"pmids\": [\"36509316\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"miR-125a-5p and miR-125b-5p directly repress ATRAP/Atrap mRNA, and inhibition of these miRNAs suppresses Ang II-AT1R signaling in mouse distal convoluted tubule cells, establishing miR-125 family members as post-transcriptional regulators of ATRAP.\",\n      \"method\": \"Luciferase reporter assay for direct miRNA-mRNA targeting, miRNA inhibitor experiments, Ang II-AT1R signaling assays in distal convoluted tubule cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct miRNA targeting validated by reporter assay with downstream signaling consequence, single lab\",\n      \"pmids\": [\"37981211\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"miR-34a directly targets AGTRAP mRNA in human aortic smooth muscle cells, reducing ATRAP and SIRT1 expression. ATRAP downmodulation further enhances miR-34a expression (negative feedback loop), and Ang II-induced pro-inflammatory gene upregulation (IL-6, COX2, MCP-1, MFGE8) is abolished by forced ATRAP expression.\",\n      \"method\": \"miR-34a target validation (direct targeting assay), gain/loss-of-function in HASMC, rescue with AGTRAP overexpression, age-associated expression analysis in primate and rodent arteries\",\n      \"journal\": \"GeroScience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — direct targeting with functional rescue, multiple model systems, single lab\",\n      \"pmids\": [\"41291382\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"AGTRAP knockdown in glioma cells suppresses IL-6 mRNA/protein levels and attenuates JAK2/STAT3 activation; recombinant IL-6 partially rescues JAK2/STAT3 signaling and growth after AGTRAP silencing, establishing that AGTRAP supports glioma cell survival via an IL-6/JAK2/STAT3 pathway.\",\n      \"method\": \"siRNA knockdown, proliferation/apoptosis assays, Western blot for JAK2/STAT3 phosphorylation, IL-6 rescue experiment, orthotopic xenograft model\",\n      \"journal\": \"CNS neuroscience & therapeutics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — epistasis via rescue experiment, in vivo validation, single lab\",\n      \"pmids\": [\"41689202\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"AGTRAP (ATRAP) is a three-pass transmembrane protein that binds the carboxyl-terminal cytoplasmic domain of the angiotensin II type 1 receptor (AT1R), promotes constitutive AT1R internalization, and thereby inhibits pathological Ang II-mediated signaling (PLC, p38 MAPK, STAT3, Akt, NF-κB, TGF-β1/Smad); it is also degraded by the immunoproteasome subunit β5i (PSMB8) and regulated post-transcriptionally by miR-125 and miR-34a, and additionally interacts with RACK1 and the Ca2+-ATPase SERCA2a to modulate cardiac Ca2+ handling.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"AGTRAP (ATRAP) is a three-pass transmembrane protein that functions as a negative regulator of angiotensin II type 1 receptor (AT1R) signaling by directly binding the AT1R carboxyl-terminal cytoplasmic domain, promoting receptor internalization and downregulation, and thereby attenuating downstream PLC, p38 MAPK, STAT3, Akt, NF-κB, and TGF-β1/Smad signaling cascades [PMID:10358057, PMID:11162453, PMID:15757644, PMID:30571551]. Agtrap-deficient mice exhibit elevated blood pressure, expanded plasma volume, and enhanced surface AT1R expression in the kidney, and under metabolic stress develop systemic insulin resistance and adipose inflammation, establishing AGTRAP as a physiological brake on AT1R-mediated renal and metabolic pathology [PMID:20093357, PMID:23902639]. Independent of its AT1R role, AGTRAP directly interacts with and stimulates the cardiac Ca²⁺-ATPase SERCA2a, facilitating sarcoplasmic reticulum Ca²⁺ reuptake and ventricular relaxation [PMID:27015675]. AGTRAP protein stability is governed by immunoproteasome-mediated degradation through the β5i (PSMB8) subunit, while its mRNA is post-transcriptionally regulated by miR-125a/b-5p and miR-34a [PMID:30571551, PMID:37981211, PMID:41291382].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Identification of ATRAP as a specific AT1R-interacting protein resolved how the receptor's cytoplasmic tail could recruit a dedicated regulatory partner distinct from generic GPCR machinery.\",\n      \"evidence\": \"Yeast two-hybrid, co-IP, affinity chromatography, and PLC activation assay in COS-7 cells\",\n      \"pmids\": [\"10358057\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Endogenous stoichiometry of ATRAP–AT1R complex unknown\", \"No structural information on the binding interface\", \"Mechanism by which ATRAP inhibits PLC activation not resolved\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Demonstrating that ATRAP potentiates AT1R internalization and suppresses STAT3/Akt phosphorylation in VSMCs established a receptor-trafficking mechanism for its inhibitory effect on Ang II-driven proliferation.\",\n      \"evidence\": \"Overexpression in VSMCs with receptor internalization, DNA synthesis, and phospho-STAT3/Akt assays\",\n      \"pmids\": [\"11162453\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Gain-of-function only; endogenous loss-of-function not tested\", \"Internalization mechanism (clathrin, caveolae) not defined\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Discovery of the ATRAP–RACK1 interaction suggested a scaffold-mediated link between AT1R signaling and PKC pathways, though functional consequence remained undefined.\",\n      \"evidence\": \"Yeast two-hybrid, GST pulldown, co-IP, and surface plasmon resonance\",\n      \"pmids\": [\"11733189\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of RACK1 interaction on AT1R signaling not tested\", \"Whether RACK1 and AT1R compete for the same ATRAP domain unknown\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Defining ATRAP as a three-pass transmembrane protein with an extracellular N-terminus and cytoplasmic C-terminal AT1R-binding domain resolved its topology and explained how it traffics constitutively between intracellular vesicles and the plasma membrane.\",\n      \"evidence\": \"Epitope topology analysis, electron microscopy, immunofluorescence, real-time vesicle tracking, C-terminal truncation mutants\",\n      \"pmids\": [\"12960423\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No high-resolution structure\", \"Signals mediating constitutive vesicular trafficking not identified\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Extension to cardiomyocytes showed that ATRAP-mediated AT1R downregulation suppresses p38 MAPK and c-fos activation, positioning ATRAP as an anti-hypertrophic factor in the heart.\",\n      \"evidence\": \"Overexpression in cardiomyocytes with surface receptor binding, phospho-p38 MAPK, reporter, and protein synthesis assays\",\n      \"pmids\": [\"15757644\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Endogenous cardiomyocyte loss-of-function not yet tested\", \"Whether ATRAP acts on cardiac AT1R specifically or also via SERCA unknown at this stage\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Agtrap knockout mice established the first in vivo loss-of-function proof that ATRAP is a physiological negative regulator of renal AT1R surface expression, controlling blood pressure and plasma volume homeostasis.\",\n      \"evidence\": \"Global Agtrap−/− mice with blood pressure telemetry, 125I-AngII binding, plasma volume measurement\",\n      \"pmids\": [\"20093357\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue-specific contributions not resolved by global KO\", \"Mechanism of increased surface AT1R beyond reduced internalization not clarified\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Fat-pad transplantation rescue in Agtrap−/− mice on high-fat diet demonstrated that adipose-expressed ATRAP protects against systemic metabolic dysfunction, broadening its role beyond hemodynamics.\",\n      \"evidence\": \"Global KO with high-fat diet plus subcutaneous fat-pad transplantation rescue, metabolic phenotyping\",\n      \"pmids\": [\"23902639\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether adipose ATRAP acts through AT1R internalization or alternative pathways not distinguished\", \"Contribution of other tissues in the global KO background not excluded\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Discovery that ATRAP directly binds and stimulates SERCA2a, facilitating Ca²⁺ reuptake and ventricular relaxation, revealed an AT1R-independent cardiac function for ATRAP.\",\n      \"evidence\": \"Pulldown with MALDI-MS identification, co-IP, SPR, Ca²⁺ uptake in SR vesicles, isolated Atrap−/− myocyte Ca²⁺ transients, echocardiography\",\n      \"pmids\": [\"27015675\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Binding site on SERCA2a not mapped\", \"Whether ATRAP–SERCA2a interaction is regulated by Ang II unknown\", \"Relative contribution of SERCA2a vs AT1R mechanisms to cardiac phenotype not dissected\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identification of β5i (PSMB8)-dependent immunoproteasomal degradation as the principal mechanism controlling ATRAP protein turnover under Ang II stimulation explained how chronic Ang II exposure amplifies its own signaling by eliminating a negative regulator.\",\n      \"evidence\": \"β5i-KO mice, AAV-mediated overexpression/rescue, proteasome activity assays in atria and retina\",\n      \"pmids\": [\"30571551\", \"31636038\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ubiquitin chain type and E3 ligase targeting ATRAP for proteasomal degradation not identified\", \"Whether standard proteasome also degrades ATRAP under basal conditions not resolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Proximal tubule-specific Agtrap deletion did not recapitulate the hypertensive phenotype of global knockouts, indicating that the blood-pressure regulatory function of ATRAP resides outside the proximal tubule.\",\n      \"evidence\": \"Pepck-Cre conditional KO mice, radiotelemetric and tail-cuff BP measurement under Ang II infusion\",\n      \"pmids\": [\"30977419\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Which nephron segment or non-renal tissue is the critical site remains unknown\", \"Compensatory upregulation in other segments not excluded\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Validation of miR-125a/b-5p as direct post-transcriptional repressors of ATRAP mRNA in distal convoluted tubule cells established a miRNA-based regulatory layer that modulates Ang II–AT1R signaling in the kidney.\",\n      \"evidence\": \"Luciferase reporter assay for direct targeting, miRNA inhibitor experiments, Ang II signaling readouts in DCT cells\",\n      \"pmids\": [\"37981211\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo relevance of miR-125 regulation of ATRAP not tested\", \"Whether other miRNAs cooperate not addressed\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"miR-34a directly targets AGTRAP mRNA in vascular smooth muscle, and ATRAP reciprocally suppresses miR-34a, forming a negative feedback loop that links vascular aging and Ang II-induced inflammation.\",\n      \"evidence\": \"miR-34a target validation, gain/loss-of-function in human aortic SMCs, age-associated expression in primate and rodent arteries\",\n      \"pmids\": [\"41291382\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which ATRAP suppresses miR-34a expression not defined\", \"In vivo miR-34a inhibition to restore ATRAP not performed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural basis of the ATRAP–AT1R and ATRAP–SERCA2a interactions, the identity of the E3 ubiquitin ligase targeting ATRAP for proteasomal degradation, and the specific tissue(s) responsible for ATRAP's blood-pressure regulatory function.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No high-resolution structure of ATRAP or its complexes\", \"E3 ligase for ATRAP ubiquitination unknown\", \"Critical tissue for blood pressure regulation not pinpointed by conditional KO studies\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 4, 6]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 3, 10]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1, 4, 6, 11]},\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [6, 10]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [9, 11, 12]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"AGTR1\", \"SERCA2a\", \"RACK1\", \"PSMB8\", \"PITPNC1\", \"USP14\", \"PBX3\"],\n    \"other_free_text\": []\n  }\n}\n```"}