{"gene":"SPINK9","run_date":"2026-06-10T07:46:40","timeline":{"discoveries":[{"year":2009,"finding":"SPINK9 (LEKTI-2) was purified from human stratum corneum and demonstrated to selectively inhibit KLK5 but not KLK7, KLK14, trypsin, plasmin, or thrombin, with an apparent Ki of 65 nM for KLK5 using low molecular weight substrates; KLK5-mediated fibrinogen degradation was also totally inhibited by SPINK9.","method":"Recombinant protein inhibition assays with multiple serine proteases; fibrinogen degradation assay; surface plasmon resonance (SPR) binding studies","journal":"The Journal of investigative dermatology","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro enzymatic assay with Ki determination, SPR binding studies, replicated across two independent labs (PMIDs 19194479 and 19190773) in the same year","pmids":["19194479","19190773"],"is_preprint":false},{"year":2009,"finding":"SPINK9 (LEKTI-2) was shown by SPR to bind KLK5 and KLK8 (heterogeneous binding) but not KLK7 or KLK14, establishing the molecular basis for its selectivity.","method":"Surface plasmon resonance (SPR) binding assay","journal":"The Journal of investigative dermatology","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — SPR binding assay in a single lab; binding to KLK8 described as heterogeneous with no inhibition confirmed","pmids":["19194479"],"is_preprint":false},{"year":2009,"finding":"SPINK9 (LEKTI-2) immunoexpression was focally localized to the stratum granulosum and stratum corneum specifically at palmar and plantar sites, in close proximity to KLK5, consistent with a functional role in regulating palmoplantar desquamation.","method":"Immunohistochemistry of human skin sections","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 3 / Strong — immunohistochemical localization replicated across two labs (PMIDs 19190773 and 19194479), providing direct evidence of co-localization with substrate KLK5","pmids":["19190773","19194479"],"is_preprint":false},{"year":2012,"finding":"The reactive loop of SPINK9 was defined at residues 48 and 49; single amino acid substitutions in this loop dramatically altered inhibitory efficiency and specificity toward KLK5, KLK7, KLK8, and KLK14. Binding studies showed that substitutions primarily affect the dissociation rate. The inhibitory effect was pH-dependent, with His48 protonation at lower pH (mimicking the outer skin pH) decreasing the dissociation rate and improving inhibition.","method":"Site-directed mutagenesis of reactive loop residues; enzyme inhibition assays; binding kinetics; molecular modeling of enzyme-inhibitor complexes","journal":"Biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — active-site mutagenesis combined with inhibition assays, binding kinetics, and structural modeling in a single rigorous study","pmids":["22505519"],"is_preprint":false},{"year":2014,"finding":"SPINK9 is constitutively secreted by keratinocytes and, independently of its KLK5-inhibitory activity, transactivates EGFR via ADAM metalloprotease upregulation to stimulate keratinocyte migration. This transactivation is mediated through purinergic receptor activation, as classical purinergic receptor antagonists (oxidized ATP and PPADS) suppressed EGFR transactivation.","method":"Recombinant SPINK9 treatment of human keratinocytes; EGFR transactivation assay; metalloproteinase inhibitor suppression; EGFR-blocking antibody; purinergic receptor antagonist experiments; cell migration assay","journal":"The Journal of investigative dermatology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple pharmacological inhibitors used orthogonally (ADAM inhibitor, EGFR antibody, purinergic antagonists) with functional migration readout in a single lab","pmids":["24441102"],"is_preprint":false},{"year":2018,"finding":"SPINK9 isolated from stratum corneum kills Escherichia coli strains; bactericidal activity is restricted to three N-terminal variants bearing lysine or glutamine as the first residue and depends on the sequence required for KLK inhibition. Ultrastructural electron microscopy showed SPINK9 enters bacterial cells. The bacterial chaperone SKP was identified as the major SPINK9-interacting partner in E. coli, and Skp-deleted bacteria were more sensitive to SPINK9, indicating SKP confers resistance.","method":"Isolation and characterization of natural N-terminal variants; bacterial killing assay; ultrastructural electron microscopy; protein interaction identification (pull-down/interactome in E. coli); Skp-deletion mutant sensitivity assay","journal":"The Journal of investigative dermatology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (killing assay, EM, genetic deletion of SKP) in a single lab establishing mechanism and interacting partner","pmids":["30468739"],"is_preprint":false}],"current_model":"SPINK9 (LEKTI-2) is a single Kazal-domain serine protease inhibitor expressed predominantly in palmoplantar epidermis that selectively inhibits KLK5 (Ki ~65 nM) through a pH-sensitive reactive loop (His48/residue 49), is constitutively secreted by keratinocytes where it can also transactivate EGFR via ADAM metalloproteases and purinergic receptors to drive cell migration, and additionally functions as an antimicrobial peptide that kills E. coli by entering the cell and overcoming resistance from the bacterial chaperone SKP."},"narrative":{"mechanistic_narrative":"SPINK9 (LEKTI-2) is a single Kazal-domain serine protease inhibitor expressed focally in the stratum granulosum and stratum corneum of palmoplantar epidermis, where it functions in the regulation of desquamation through highly selective inhibition of the kallikrein KLK5 [PMID:19194479, PMID:19190773]. It binds and inhibits KLK5 (apparent Ki ~65 nM) while sparing KLK7, KLK14, trypsin, plasmin, and thrombin, and fully blocks KLK5-mediated fibrinogen degradation [PMID:19194479, PMID:19190773]. Selectivity and inhibitory potency are governed by its reactive loop at residues 48/49, where protonation of His48 at the acidic pH of outer skin slows the enzyme-inhibitor dissociation rate and enhances inhibition, providing a pH-tuned mechanism matched to the epidermal microenvironment [PMID:22505519]. Beyond protease inhibition, SPINK9 is constitutively secreted by keratinocytes and, independently of its KLK5-inhibitory activity, transactivates EGFR through ADAM metalloprotease upregulation and purinergic receptor signaling to stimulate keratinocyte migration [PMID:24441102]. It additionally acts as an antimicrobial peptide that enters and kills Escherichia coli in a manner dependent on its N-terminal sequence and the KLK-inhibitory motif, with the bacterial chaperone SKP identified as its major interacting partner conferring bacterial resistance [PMID:30468739].","teleology":[{"year":2009,"claim":"Established SPINK9 as a protease inhibitor and resolved which protease it targets, defining its biochemical function and selectivity.","evidence":"Recombinant inhibition assays against multiple serine proteases with Ki determination, SPR binding, and fibrinogen degradation assay; immunohistochemistry localizing SPINK9 near KLK5 in palmoplantar skin","pmids":["19194479","19190773"],"confidence":"High","gaps":["KLK8 binding was heterogeneous and no inhibition was confirmed","Physiological consequence of KLK5 inhibition on desquamation not demonstrated in vivo","No structural model of the inhibitory complex at this stage"]},{"year":2012,"claim":"Pinpointed the structural determinants of inhibition, showing how reactive-loop residues and pH control specificity and potency toward kallikreins.","evidence":"Site-directed mutagenesis of reactive-loop residues 48/49, inhibition assays, binding kinetics, and molecular modeling of enzyme-inhibitor complexes","pmids":["22505519"],"confidence":"High","gaps":["No experimental crystal structure of the SPINK9-KLK5 complex","pH dependence shown biochemically but not validated in tissue context"]},{"year":2014,"claim":"Revealed a protease-inhibition-independent signaling role, expanding SPINK9 function from passive inhibitor to active driver of keratinocyte behavior.","evidence":"Recombinant SPINK9 treatment of keratinocytes with EGFR transactivation assays, ADAM metalloproteinase inhibitor, EGFR-blocking antibody, purinergic antagonists, and migration readouts","pmids":["24441102"],"confidence":"Medium","gaps":["Single lab; no identification of the specific purinergic receptor or ADAM isoform","Direct receptor for SPINK9 not identified","In vivo relevance to wound healing or migration not shown"]},{"year":2018,"claim":"Demonstrated a third function as an antimicrobial peptide and identified its bacterial target interaction, linking the KLK-inhibitory motif to bactericidal activity.","evidence":"Characterization of natural N-terminal variants, bacterial killing assays, ultrastructural EM showing cell entry, E. coli interactome pull-down identifying SKP, and Skp-deletion sensitivity assay","pmids":["30468739"],"confidence":"Medium","gaps":["Single lab; mechanism of intracellular killing after entry not defined","Activity tested mainly against E. coli; spectrum across other organisms limited","How SKP confers resistance mechanistically unresolved"]},{"year":null,"claim":"Whether SPINK9's three activities (KLK5 inhibition, EGFR transactivation, antimicrobial killing) are integrated in palmoplantar skin physiology or pathology remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No in vivo or disease-association evidence in the corpus","No genetic loss-of-function phenotype reported","Relationship between the secreted signaling pool and the desquamation-regulating pool unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,3]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,3]}],"localization":[{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[0,2,4]}],"pathway":[],"complexes":[],"partners":["KLK5","SKP"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q5DT21","full_name":"Serine protease inhibitor Kazal-type 9","aliases":["Lymphoepithelial Kazal-type-related inhibitor 2"],"length_aa":86,"mass_kda":9.8,"function":"Serine protease inhibitor which specifically inhibits KLK5. May contribute to the regulation of the desquamation process in skin by inhibiting KLK5","subcellular_location":"Secreted","url":"https://www.uniprot.org/uniprotkb/Q5DT21/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SPINK9","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SPINK9","total_profiled":1310},"omim":[{"mim_id":"615868","title":"SERINE PEPTIDASE INHIBITOR, KAZAL-TYPE, 6; SPINK6","url":"https://www.omim.org/entry/615868"},{"mim_id":"613511","title":"SERINE PROTEASE INHIBITOR, KAZAL-TYPE, 9; SPINK9","url":"https://www.omim.org/entry/613511"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Vesicles","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"bone marrow","ntpm":2.3},{"tissue":"lymphoid tissue","ntpm":2.6},{"tissue":"retina","ntpm":2.0}],"url":"https://www.proteinatlas.org/search/SPINK9"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"Q5DT21","domains":[{"cath_id":"3.30.60.30","chopping":"2-29_47-84","consensus_level":"medium","plddt":90.7224,"start":2,"end":84}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q5DT21","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q5DT21-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q5DT21-F1-predicted_aligned_error_v6.png","plddt_mean":91.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SPINK9","jax_strain_url":"https://www.jax.org/strain/search?query=SPINK9"},"sequence":{"accession":"Q5DT21","fasta_url":"https://rest.uniprot.org/uniprotkb/Q5DT21.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q5DT21/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q5DT21"}},"corpus_meta":[{"pmid":"20667819","id":"PMC_20667819","title":"Isolation of SPINK6 in human skin: selective inhibitor of kallikrein-related peptidases.","date":"2010","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/20667819","citation_count":70,"is_preprint":false},{"pmid":"19194479","id":"PMC_19194479","title":"SPINK9: a selective, skin-specific Kazal-type serine protease inhibitor.","date":"2009","source":"The Journal of investigative dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/19194479","citation_count":54,"is_preprint":false},{"pmid":"19190773","id":"PMC_19190773","title":"Identification of lympho-epithelial Kazal-type inhibitor 2 in human skin as a kallikrein-related peptidase 5-specific protease inhibitor.","date":"2009","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/19190773","citation_count":54,"is_preprint":false},{"pmid":"22505519","id":"PMC_22505519","title":"Characterization of SPINK9, a KLK5-specific inhibitor expressed in palmo-plantar epidermis.","date":"2012","source":"Biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22505519","citation_count":16,"is_preprint":false},{"pmid":"24441102","id":"PMC_24441102","title":"SPINK9 stimulates metalloprotease/EGFR-dependent keratinocyte migration via purinergic receptor activation.","date":"2014","source":"The Journal of investigative dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/24441102","citation_count":15,"is_preprint":false},{"pmid":"30468739","id":"PMC_30468739","title":"Skin-Derived SPINK9 Kills Escherichia coli.","date":"2018","source":"The Journal of investigative dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/30468739","citation_count":11,"is_preprint":false},{"pmid":"26746658","id":"PMC_26746658","title":"The serine protease inhibitor of Kazal-type 9 (SPINK9) is expressed in lichen simplex chronicus, actinic keratosis and squamous cell carcinoma.","date":"2016","source":"Archives of dermatological research","url":"https://pubmed.ncbi.nlm.nih.gov/26746658","citation_count":7,"is_preprint":false},{"pmid":"23039091","id":"PMC_23039091","title":"Keratolysis exfoliativa (dyshidrosis lamellosa sicca): a distinct peeling entity.","date":"2012","source":"The British journal of dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/23039091","citation_count":6,"is_preprint":false},{"pmid":"36175575","id":"PMC_36175575","title":"Identification of novel differentially expressed genes in type 1 diabetes mellitus complications using transcriptomic profiling of UAE patients: a multicenter study.","date":"2022","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/36175575","citation_count":4,"is_preprint":false},{"pmid":"41616039","id":"PMC_41616039","title":"Identification of deleterious missense variants of serine peptidase inhibitor Kazal type 2 gene and their impact on KAZAL domain structure, stability, flexibility, and dimension.","date":"2026","source":"Journal of biomolecular structure & dynamics","url":"https://pubmed.ncbi.nlm.nih.gov/41616039","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7164,"output_tokens":1686,"usd":0.023391,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8485,"output_tokens":1959,"usd":0.0457,"stage2_stop_reason":"end_turn"},"total_usd":0.069091,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2009,\n      \"finding\": \"SPINK9 (LEKTI-2) was purified from human stratum corneum and demonstrated to selectively inhibit KLK5 but not KLK7, KLK14, trypsin, plasmin, or thrombin, with an apparent Ki of 65 nM for KLK5 using low molecular weight substrates; KLK5-mediated fibrinogen degradation was also totally inhibited by SPINK9.\",\n      \"method\": \"Recombinant protein inhibition assays with multiple serine proteases; fibrinogen degradation assay; surface plasmon resonance (SPR) binding studies\",\n      \"journal\": \"The Journal of investigative dermatology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro enzymatic assay with Ki determination, SPR binding studies, replicated across two independent labs (PMIDs 19194479 and 19190773) in the same year\",\n      \"pmids\": [\"19194479\", \"19190773\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"SPINK9 (LEKTI-2) was shown by SPR to bind KLK5 and KLK8 (heterogeneous binding) but not KLK7 or KLK14, establishing the molecular basis for its selectivity.\",\n      \"method\": \"Surface plasmon resonance (SPR) binding assay\",\n      \"journal\": \"The Journal of investigative dermatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — SPR binding assay in a single lab; binding to KLK8 described as heterogeneous with no inhibition confirmed\",\n      \"pmids\": [\"19194479\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"SPINK9 (LEKTI-2) immunoexpression was focally localized to the stratum granulosum and stratum corneum specifically at palmar and plantar sites, in close proximity to KLK5, consistent with a functional role in regulating palmoplantar desquamation.\",\n      \"method\": \"Immunohistochemistry of human skin sections\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Strong — immunohistochemical localization replicated across two labs (PMIDs 19190773 and 19194479), providing direct evidence of co-localization with substrate KLK5\",\n      \"pmids\": [\"19190773\", \"19194479\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The reactive loop of SPINK9 was defined at residues 48 and 49; single amino acid substitutions in this loop dramatically altered inhibitory efficiency and specificity toward KLK5, KLK7, KLK8, and KLK14. Binding studies showed that substitutions primarily affect the dissociation rate. The inhibitory effect was pH-dependent, with His48 protonation at lower pH (mimicking the outer skin pH) decreasing the dissociation rate and improving inhibition.\",\n      \"method\": \"Site-directed mutagenesis of reactive loop residues; enzyme inhibition assays; binding kinetics; molecular modeling of enzyme-inhibitor complexes\",\n      \"journal\": \"Biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — active-site mutagenesis combined with inhibition assays, binding kinetics, and structural modeling in a single rigorous study\",\n      \"pmids\": [\"22505519\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"SPINK9 is constitutively secreted by keratinocytes and, independently of its KLK5-inhibitory activity, transactivates EGFR via ADAM metalloprotease upregulation to stimulate keratinocyte migration. This transactivation is mediated through purinergic receptor activation, as classical purinergic receptor antagonists (oxidized ATP and PPADS) suppressed EGFR transactivation.\",\n      \"method\": \"Recombinant SPINK9 treatment of human keratinocytes; EGFR transactivation assay; metalloproteinase inhibitor suppression; EGFR-blocking antibody; purinergic receptor antagonist experiments; cell migration assay\",\n      \"journal\": \"The Journal of investigative dermatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple pharmacological inhibitors used orthogonally (ADAM inhibitor, EGFR antibody, purinergic antagonists) with functional migration readout in a single lab\",\n      \"pmids\": [\"24441102\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"SPINK9 isolated from stratum corneum kills Escherichia coli strains; bactericidal activity is restricted to three N-terminal variants bearing lysine or glutamine as the first residue and depends on the sequence required for KLK inhibition. Ultrastructural electron microscopy showed SPINK9 enters bacterial cells. The bacterial chaperone SKP was identified as the major SPINK9-interacting partner in E. coli, and Skp-deleted bacteria were more sensitive to SPINK9, indicating SKP confers resistance.\",\n      \"method\": \"Isolation and characterization of natural N-terminal variants; bacterial killing assay; ultrastructural electron microscopy; protein interaction identification (pull-down/interactome in E. coli); Skp-deletion mutant sensitivity assay\",\n      \"journal\": \"The Journal of investigative dermatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (killing assay, EM, genetic deletion of SKP) in a single lab establishing mechanism and interacting partner\",\n      \"pmids\": [\"30468739\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SPINK9 (LEKTI-2) is a single Kazal-domain serine protease inhibitor expressed predominantly in palmoplantar epidermis that selectively inhibits KLK5 (Ki ~65 nM) through a pH-sensitive reactive loop (His48/residue 49), is constitutively secreted by keratinocytes where it can also transactivate EGFR via ADAM metalloproteases and purinergic receptors to drive cell migration, and additionally functions as an antimicrobial peptide that kills E. coli by entering the cell and overcoming resistance from the bacterial chaperone SKP.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"SPINK9 (LEKTI-2) is a single Kazal-domain serine protease inhibitor expressed focally in the stratum granulosum and stratum corneum of palmoplantar epidermis, where it functions in the regulation of desquamation through highly selective inhibition of the kallikrein KLK5 [#0, #2]. It binds and inhibits KLK5 (apparent Ki ~65 nM) while sparing KLK7, KLK14, trypsin, plasmin, and thrombin, and fully blocks KLK5-mediated fibrinogen degradation [#0]. Selectivity and inhibitory potency are governed by its reactive loop at residues 48/49, where protonation of His48 at the acidic pH of outer skin slows the enzyme-inhibitor dissociation rate and enhances inhibition, providing a pH-tuned mechanism matched to the epidermal microenvironment [#3]. Beyond protease inhibition, SPINK9 is constitutively secreted by keratinocytes and, independently of its KLK5-inhibitory activity, transactivates EGFR through ADAM metalloprotease upregulation and purinergic receptor signaling to stimulate keratinocyte migration [#4]. It additionally acts as an antimicrobial peptide that enters and kills Escherichia coli in a manner dependent on its N-terminal sequence and the KLK-inhibitory motif, with the bacterial chaperone SKP identified as its major interacting partner conferring bacterial resistance [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2009,\n      \"claim\": \"Established SPINK9 as a protease inhibitor and resolved which protease it targets, defining its biochemical function and selectivity.\",\n      \"evidence\": \"Recombinant inhibition assays against multiple serine proteases with Ki determination, SPR binding, and fibrinogen degradation assay; immunohistochemistry localizing SPINK9 near KLK5 in palmoplantar skin\",\n      \"pmids\": [\"19194479\", \"19190773\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"KLK8 binding was heterogeneous and no inhibition was confirmed\", \"Physiological consequence of KLK5 inhibition on desquamation not demonstrated in vivo\", \"No structural model of the inhibitory complex at this stage\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Pinpointed the structural determinants of inhibition, showing how reactive-loop residues and pH control specificity and potency toward kallikreins.\",\n      \"evidence\": \"Site-directed mutagenesis of reactive-loop residues 48/49, inhibition assays, binding kinetics, and molecular modeling of enzyme-inhibitor complexes\",\n      \"pmids\": [\"22505519\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No experimental crystal structure of the SPINK9-KLK5 complex\", \"pH dependence shown biochemically but not validated in tissue context\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Revealed a protease-inhibition-independent signaling role, expanding SPINK9 function from passive inhibitor to active driver of keratinocyte behavior.\",\n      \"evidence\": \"Recombinant SPINK9 treatment of keratinocytes with EGFR transactivation assays, ADAM metalloproteinase inhibitor, EGFR-blocking antibody, purinergic antagonists, and migration readouts\",\n      \"pmids\": [\"24441102\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; no identification of the specific purinergic receptor or ADAM isoform\", \"Direct receptor for SPINK9 not identified\", \"In vivo relevance to wound healing or migration not shown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Demonstrated a third function as an antimicrobial peptide and identified its bacterial target interaction, linking the KLK-inhibitory motif to bactericidal activity.\",\n      \"evidence\": \"Characterization of natural N-terminal variants, bacterial killing assays, ultrastructural EM showing cell entry, E. coli interactome pull-down identifying SKP, and Skp-deletion sensitivity assay\",\n      \"pmids\": [\"30468739\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; mechanism of intracellular killing after entry not defined\", \"Activity tested mainly against E. coli; spectrum across other organisms limited\", \"How SKP confers resistance mechanistically unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether SPINK9's three activities (KLK5 inhibition, EGFR transactivation, antimicrobial killing) are integrated in palmoplantar skin physiology or pathology remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No in vivo or disease-association evidence in the corpus\", \"No genetic loss-of-function phenotype reported\", \"Relationship between the secreted signaling pool and the desquamation-regulating pool unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [0, 2, 4]}\n    ],\n    \"pathway\": [],\n    \"complexes\": [],\n    \"partners\": [\"KLK5\", \"SKP\"],\n    \"other_free_text\": []\n  }\n}\n```","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":4,"faith_total":5,"faith_pct":80.0}}