{"gene":"TMPRSS13","run_date":"2026-06-13T19:06:35","timeline":{"discoveries":[{"year":2008,"finding":"MSPL and its splice variant TMPRSS13 are type II transmembrane serine proteases with a cytoplasmic tail containing tandem repeat phosphorylation motifs, a transmembrane domain, and a trypsin-like serine protease domain. Recombinant soluble MSPL and TMPRSS13 preferentially cleave paired basic amino acid residues and are strongly inhibited by aprotinin, benzamidine, and Bowman-Birk trypsin inhibitor, but poorly inhibited by alpha1-antitrypsin and leupeptin.","method":"Recombinant protein expression, enzymatic assay with synthetic substrates and inhibitors, structural domain analysis from cDNA","journal":"Frontiers in bioscience","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro enzymatic characterization of recombinant protein, single lab, foundational characterization paper","pmids":["17981585"],"is_preprint":false},{"year":2010,"finding":"MSPL and TMPRSS13 proteolytically cleave the hemagglutinin (HA) of highly pathogenic avian influenza (HPAI) viruses at both R/K-K-K-R cleavage site motifs, activating membrane fusion. Unlike furin, MSPL and TMPRSS13 cleave both types of HA multibasic cleavage motifs (R-X-K/R-R and K-K/R-K/T-R) in a calcium-independent manner, and their activity is suppressible by specific inhibitors. Expression of MSPL or TMPRSS13 in transfected cells enabled multicycle replication of HPAI viruses with the K-K-K-R motif.","method":"Synthetic peptide cleavage assays, transfection of full-length recombinant HPAI HA, cell-based membrane fusion assay, inhibitor studies, viral infection assay in protease-expressing cells","journal":"Journal of virology","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple orthogonal methods (in vitro peptide cleavage, cell-based HA processing, viral replication, inhibitor suppression), single lab with rigorous controls","pmids":["20219906"],"is_preprint":false},{"year":2010,"finding":"TMPRSS13 proteolytic activity is inhibited by hepatocyte growth factor activator inhibitor type 1 (HAI-1). A soluble form of HAI-1 containing one Kunitz domain (NK1) forms a complex with TMPRSS13 and more strongly inhibits it than the two-Kunitz-domain form (NK1LK2). TMPRSS13 converts single-chain pro-HGF to the active two-chain form in vitro, and this activity is inhibited by NK1. The resulting active HGF induces phosphorylation of c-Met and ERK, and scattered morphology in HepG2 cells.","method":"In vitro protein binding assay (complex formation), enzymatic inhibition assay, in vitro pro-HGF cleavage assay, cell-based signaling assay (c-Met/ERK phosphorylation, morphology)","journal":"The FEBS journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution of inhibitor-enzyme complex, in vitro substrate cleavage assay, cell-based functional validation, multiple orthogonal methods in single lab","pmids":["20977675"],"is_preprint":false},{"year":2014,"finding":"MSPL (TMPRSS13) and DESC1 cleave and activate the spike proteins of MERS-CoV and SARS-CoV for cell-cell and virus-cell fusion. MSPL and DESC1 are expressed in human lung tissue and support spread of all influenza virus subtypes previously pandemic in humans.","method":"Cell-cell and virus-cell fusion assays, spike protein cleavage assays, expression analysis in human lung tissue, viral amplification assays","journal":"Journal of virology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional cell-based assays for spike cleavage and fusion, viral replication, tissue expression confirmation, single lab","pmids":["25122802"],"is_preprint":false},{"year":2014,"finding":"TMPRSS13 (Tmprss13) is highly expressed in epithelia of the oral cavity, upper digestive tract, and skin. Genetic disruption of Tmprss13 in mice causes abnormal skin development and compromised epidermal barrier function, as measured by increased transepidermal fluid loss in newborn mice.","method":"Beta-galactosidase reporter knock-in mouse model, transepidermal water loss measurement, histological analysis","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean genetic knockout with defined tissue expression and quantitative functional phenotype (barrier measurement), single lab with multiple methods","pmids":["24832573"],"is_preprint":false},{"year":2017,"finding":"TMPRSS13 is a glycosylated, active protease that undergoes autoactivation through its own proteolytic activity (zymogen cleavage). Full-length active TMPRSS13 shows impaired cell-surface expression without its cognate inhibitors HAI-1 or HAI-2. Co-presence of TMPRSS13 with HAI-1 or HAI-2 mediates phosphorylation of residues in the intracellular domain, coinciding with efficient transport to the cell surface and subsequent shedding. The dominant cell-surface form of TMPRSS13 is phosphorylated, while intracellular TMPRSS13 is predominantly non-phosphorylated.","method":"Cell-surface labeling experiments, Western blotting, co-expression studies, site-directed mutagenesis (implied by activation analysis), subcellular fractionation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal approaches (surface labeling, biochemical fractionation, co-expression with inhibitors), single lab demonstrating post-translational modification linked to localization","pmids":["28710277"],"is_preprint":false},{"year":2017,"finding":"MSPL (and TMPRSS2) promotes porcine epidemic diarrhea virus (PEDV) cell-cell fusion and virus-cell fusion. MSPL co-localizes with and cleaves the PEDV spike (S) protein, enabling multicycle PEDV replication in Vero cells in the absence of exogenous trypsin.","method":"Cell-based fusion assay, co-localization experiments, S protein cleavage assay by co-expression, viral replication assay in MSPL-expressing cells","journal":"Viruses","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-localization and S protein cleavage by co-expression, functional viral replication assay, single lab","pmids":["28524070"],"is_preprint":false},{"year":2020,"finding":"TMPRSS13 promotes breast cancer progression; siRNA-mediated silencing decreases proliferation, induces apoptosis, and attenuates invasion in human breast cancer cell lines. Genetic ablation of TMPRSS13 in the MMTV-PymT transgenic mouse model reduces overall tumor burden, growth rate, and delays tumor formation. TMPRSS13 knockdown increases prostasin protein levels, and co-immunoprecipitation and prostasin zymogen activation experiments identify prostasin as a potential TMPRSS13 substrate.","method":"siRNA knockdown, transgenic mouse tumor model (TMPRSS13 KO x MMTV-PymT), proliferation/apoptosis/invasion assays, co-immunoprecipitation, prostasin zymogen activation assay","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo KO tumor model plus in vitro mechanistic substrate identification via Co-IP and zymogen activation, multiple orthogonal methods","pmids":["32868877"],"is_preprint":false},{"year":2020,"finding":"TMPRSS13 silencing in colorectal cancer (CRC) cell lines increases apoptosis and impairs invasive potential. Transgenic overexpression of TMPRSS13 increases tolerance to apoptosis-inducing agents (paclitaxel, HA14-1), while silencing renders CRC cells more sensitive. TMPRSS13 thus promotes cell survival and resistance to drug-induced apoptosis in CRC.","method":"siRNA knockdown, transgenic overexpression, apoptosis assays, invasion assays, drug sensitivity assays (paclitaxel, HA14-1)","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — complementary gain- and loss-of-function experiments with multiple functional readouts, single lab","pmids":["32807808"],"is_preprint":false},{"year":2021,"finding":"TMPRSS11D and TMPRSS13 enhance cellular uptake and replication of SARS-CoV-2 when exogenously expressed in ACE2-expressing HEK293T or Vero E6 cells. TMPRSS13 activates the SARS-CoV-2 spike protein to facilitate cellular entry, and this mechanism is shared with SARS-CoV-1.","method":"Exogenous expression screen of 12 TTSPs, pseudovirus entry assay, live virus replication assay in ACE2-expressing cells","journal":"Viruses","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional screen with live virus and pseudovirus validation, single lab, multiple cell systems","pmids":["33671076"],"is_preprint":false},{"year":2021,"finding":"Crystal structure of the extracellular region of human MSPL (TMPRSS13) in complex with an irreversible substrate-analog inhibitor was solved. The structure revealed three domains clustered around the C-terminal alpha-helix of the serine protease domain (SPD). The P1-Arg inserts into the S1 pocket, while P2-Lys and P4-Arg interact with a unique Asp/Glu-rich 99-loop of MSPL that determines its specificity for [R/K]-K-K-R sequences.","method":"X-ray crystallography, inhibitor complex structure determination, structural analysis of substrate-binding determinants","journal":"Life science alliance","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with bound inhibitor revealing catalytic mechanism and substrate specificity determinants, single lab with rigorous structural data","pmids":["33820827"],"is_preprint":false},{"year":2021,"finding":"N-linked glycosylation of the serine protease (SP) domain of TMPRSS13 is critical for autoactivation, catalytic activity toward the prostasin zymogen substrate, and cell-surface trafficking; glycosylation-deficient SP domain mutants are retained in the endoplasmic reticulum. N-linked glycosylation is also a prerequisite for subsequent phosphorylation of TMPRSS13.","method":"Site-directed mutagenesis of glycosylation sites (individual and combinatorial), Western blotting, immunofluorescence/ER localization, prostasin zymogen activation assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — site-directed mutagenesis of four glycosylation sites with functional readouts for activity, localization, and phosphorylation, single lab with multiple orthogonal methods","pmids":["34562451"],"is_preprint":false},{"year":2022,"finding":"TMPRSS13 cleaves the SARS-CoV-2 spike S2' motif (811-KPSKR-815) in a sequence-dependent manner that differs from TMPRSS2: residue K814 (preceding the scissile R815) is dispensable for TMPRSS2 activation but is favored by TMPRSS13. TMPRSS13 requires a sequence rich in K/R residues at the S2' site, while TMPRSS2 is more tolerant of variation. Swapping the SARS-CoV-2 S2' motif with that of 229E coronavirus drastically reduced TMPRSS13-mediated activation but had no effect on TMPRSS2.","method":"Site-directed mutagenesis of spike S2' motif, pseudovirus entry assay, Calu-3 cell entry experiments, comparative analysis of TMPRSS2 vs TMPRSS13 substrate specificity","journal":"mBio","confidence":"High","confidence_rationale":"Tier 1 / Moderate — systematic mutagenesis with pseudovirus functional assay and orthogonal cell line validation defining substrate cleavage determinants, single lab with multiple spike variants","pmids":["35913162"],"is_preprint":false},{"year":2022,"finding":"TMPRSS13 zymogen activation, cell-surface localization, shedding, and phosphorylation require proteolytic cleavage within the extracellular stem region between the transmembrane domain and the SRCR domain. This stem cleavage depends on TMPRSS13's own catalytic activity (autonomous mechanism). Mutagenesis of 10 basic residues (4 Arg, 6 Lys) in the stem region abrogated all these processing steps. Specifically, R223 (between the LDLRA and SRCR domains) was identified as an important site for stem region cleavage.","method":"Site-directed mutagenesis (individual and combinatorial basic residue mutations), Western blotting for zymogen activation and shedding, flow cytometry for cell surface expression, phosphorylation analysis","journal":"Biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — systematic site-directed mutagenesis of stem region with multiple orthogonal functional readouts (activation, surface expression, shedding, phosphorylation), single lab","pmids":["35796294"],"is_preprint":false},{"year":2022,"finding":"IL4I1 (interleukin four-induced gene 1), a secreted enzyme, binds to TMPRSS13 on the cell surface of human lymphocytes, monocytes, and macrophages. IL4I1 and SARS-CoV-2 spike share regions of homology and compete for binding to TMPRSS13.","method":"Binding assay (identified by protein interaction screen), competition assay between IL4I1 and spike protein for TMPRSS13, pseudotyped virus entry assay, cell-surface expression analysis","journal":"Frontiers in immunology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — binding and competition demonstrated but details of binding assay methodology limited in abstract, single lab","pmids":["36131918"],"is_preprint":false},{"year":2024,"finding":"TMPRSS13 promotes SADS-CoV cell entry specifically at the membrane fusion step by cleaving the SADS-CoV spike protein. Both human and pig TMPRSS13 enhance cell-cell membrane fusion and spike cleavage. This activity is sensitive to the serine protease inhibitor camostat. TMPRSS13 specifically facilitates trypsin-dependent (not trypsin-independent) SADS-CoV infection.","method":"CRISPR-based endogenous activation screen of all 18 TTSP members, ectopic expression validation, pseudovirus entry assay with SADS-CoV spike, cell-cell fusion assay, spike cleavage assay, camostat inhibitor treatment","journal":"Journal of medical virology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — systematic CRISPR screen followed by multiple orthogonal validation methods (ectopic expression, pseudovirus entry, fusion assay, inhibitor), single lab","pmids":["38808555"],"is_preprint":false},{"year":2024,"finding":"TMPRSS13 undergoes intracellular autoactivation in the endoplasmic reticulum and Golgi apparatus. HAI-1 facilitates TMPRSS13 activation, protects it from autodegradation (trans-autodegradation), and stabilizes its cell-surface expression—distinct from its effect on HPN and TMPRSS2. Active TMPRSS13 is subject to trans-autodegradation that reduces cell-surface expression.","method":"Site-directed mutagenesis, Western blotting, flow cytometry, immunostaining, brefeldin A and monensin treatment (Golgi/ER trafficking inhibitors), co-transfection assays","journal":"Life sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple pharmacological and genetic approaches to dissect intracellular activation and trafficking, single lab","pmids":["39643034"],"is_preprint":false},{"year":2025,"finding":"Ketobenzothiazole-based peptidomimetic inhibitors were developed for TMPRSS13 through screening a 65-compound library against recombinant active TMPRSS13. Lead inhibitor N-0430 achieved low nanomolar affinity toward TMPRSS13 in a cellular context. Molecular modelling identified key molecular determinants of TMPRSS13 inhibition. N-0430 blocked TMPRSS13-dependent SARS-CoV-2 pseudovirus cell entry.","method":"In vitro enzymatic screening of compound library against recombinant TMPRSS13, molecular modelling, cellular TMPRSS13 activity assay, SARS-CoV-2 pseudovirus entry inhibition assay","journal":"Journal of enzyme inhibition and medicinal chemistry","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro enzymatic screening with cellular validation and pseudovirus functional assay, single lab","pmids":["39976239"],"is_preprint":false}],"current_model":"TMPRSS13 (MSPL) is a type II transmembrane serine protease that undergoes intracellular autoactivation via autonomous stem-region cleavage, is regulated by N-linked glycosylation (required for activation, catalytic activity, and ER-to-surface trafficking) and phosphorylation of its intracellular domain (promoted by HAI-1/HAI-2 and linked to cell-surface localization and shedding), preferentially cleaves polybasic R/K-K-K-R sequences, activates pro-HGF and the prostasin zymogen as endogenous substrates, is inhibited by HAI-1 through a Kunitz domain interaction, promotes epidermal barrier formation and breast/colorectal cancer progression, and serves as a host cell activating protease for highly pathogenic influenza HA proteins, SARS-CoV-1/2 spike, MERS-CoV spike, PEDV S, and SADS-CoV spike by cleaving multibasic cleavage motifs to enable membrane fusion and viral entry."},"narrative":{"mechanistic_narrative":"TMPRSS13 (MSPL) is a type II transmembrane serine protease that governs pericellular proteolysis at epithelial surfaces and serves as a host activating protease for diverse viral envelope glycoproteins [PMID:17981585, PMID:20219906]. Its catalytic domain preferentially cleaves polybasic [R/K]-K-K-R motifs, a specificity dictated by a unique Asp/Glu-rich 99-loop that engages the P2-Lys and P4-Arg of the substrate while the P1-Arg inserts into the S1 pocket [PMID:17981585, PMID:33820827]. Maturation proceeds by autonomous, intracellular autoactivation in the ER and Golgi via cleavage within the extracellular stem region, with R223 a critical scissile site; this processing is required for catalytic activity, surface trafficking, and shedding [PMID:35796294, PMID:39643034]. N-linked glycosylation of the protease domain is a prerequisite for autoactivation, catalytic activity, and ER-to-surface export, and is itself required for downstream phosphorylation of the intracellular domain [PMID:34562451]. The cognate Kunitz-type inhibitors HAI-1 and HAI-2 both restrain catalytic activity and paradoxically promote its phosphorylation, surface localization, and stability by protecting TMPRSS13 from trans-autodegradation [PMID:20977675, PMID:28710277, PMID:39643034]. Endogenous substrates include pro-HGF, whose activation triggers c-Met/ERK signaling, and the prostasin zymogen [PMID:20977675, PMID:32868877]. Physiologically, TMPRSS13 is expressed in oral, digestive, and skin epithelia and is required for epidermal barrier formation, and it drives breast and colorectal cancer progression by supporting proliferation, invasion, and resistance to apoptosis [PMID:24832573, PMID:32868877, PMID:32807808]. As a host protease, TMPRSS13 cleaves the multibasic activation motifs of highly pathogenic influenza HA and the spike proteins of SARS-CoV-1/2, MERS-CoV, PEDV, and SADS-CoV to enable membrane fusion and viral entry, with S2' cleavage requiring a K/R-rich motif distinct from the determinants used by TMPRSS2 [PMID:20219906, PMID:25122802, PMID:33671076, PMID:35913162, PMID:38808555].","teleology":[{"year":2008,"claim":"Establishing that MSPL/TMPRSS13 are type II transmembrane serine proteases with a defined domain architecture and basic-residue cleavage preference set the foundation for all subsequent substrate work.","evidence":"Recombinant soluble protein expression with synthetic substrate and inhibitor profiling, plus cDNA domain analysis","pmids":["17981585"],"confidence":"Medium","gaps":["No physiological substrate or in vivo role identified","Specificity defined only by synthetic peptides, not endogenous proteins"]},{"year":2010,"claim":"The first physiological and pathophysiological substrates emerged: TMPRSS13 activates influenza HA multibasic motifs and converts pro-HGF to active HGF, linking the protease to viral entry and growth-factor signaling.","evidence":"Peptide cleavage, full-length HA processing, cell-based fusion and viral replication assays; in vitro pro-HGF cleavage with c-Met/ERK readout; HAI-1 inhibition assays","pmids":["20219906","20977675"],"confidence":"High","gaps":["Endogenous (non-overexpression) contribution to viral spread not established","HGF activation shown in vitro/cell lines, not in tissue"]},{"year":2014,"claim":"Genetic and tissue evidence established a physiological role in epithelial barrier biology and extended viral activation to coronaviruses.","evidence":"Tmprss13 reporter knock-in mouse with transepidermal water loss and histology; spike cleavage and fusion assays for MERS-CoV/SARS-CoV in lung-expressed protease","pmids":["24832573","25122802"],"confidence":"High","gaps":["Endogenous epidermal substrate driving barrier defect not identified","Coronavirus activation tested largely by overexpression"]},{"year":2017,"claim":"Defining the autoactivation and HAI-dependent regulatory logic explained how an active intracellular protease reaches and is controlled at the cell surface.","evidence":"Surface labeling, subcellular fractionation, co-expression with HAI-1/HAI-2, phosphorylation analysis","pmids":["28710277"],"confidence":"High","gaps":["Kinase responsible for intracellular-domain phosphorylation not identified","Functional consequence of shedding unresolved"]},{"year":2020,"claim":"Loss- and gain-of-function studies established TMPRSS13 as a driver of breast and colorectal cancer and identified prostasin as an endogenous substrate.","evidence":"siRNA knockdown, transgenic KO x MMTV-PymT tumor model, proliferation/apoptosis/invasion assays, Co-IP and prostasin zymogen activation; CRC drug-sensitivity assays","pmids":["32868877","32807808"],"confidence":"High","gaps":["Prostasin identified by Co-IP/zymogen assay without reciprocal validation in vivo","Mechanism linking proteolysis to apoptosis resistance undefined"]},{"year":2021,"claim":"Structural and post-translational studies resolved the molecular basis of substrate specificity and the requirement of glycosylation for maturation, while expanding viral substrates to SARS-CoV-2.","evidence":"Crystal structure with substrate-analog inhibitor; glycosylation-site mutagenesis with activity/localization/phosphorylation readouts; TTSP expression screen with pseudovirus and live SARS-CoV-2 entry","pmids":["33820827","34562451","33671076"],"confidence":"High","gaps":["Structure captures inhibitor complex, not native substrate or full-length protein","SARS-CoV-2 entry assessed under exogenous overexpression"]},{"year":2022,"claim":"Mechanistic dissection located the autoactivation cleavage to the extracellular stem region (R223), defined a K/R-rich S2' cleavage determinant distinct from TMPRSS2, and identified IL4I1 as a surface-binding partner competing with spike.","evidence":"Stem-region basic-residue mutagenesis with activation/surface/shedding/phosphorylation readouts; spike S2' mutagenesis with pseudovirus and Calu-3 entry; IL4I1 binding and spike-competition assays","pmids":["35796294","35913162","36131918"],"confidence":"High","gaps":["Physiological role of IL4I1-TMPRSS13 interaction unresolved","Whether stem cleavage occurs in cis or trans not fully established"]},{"year":2024,"claim":"Compartmental and stability mechanisms were refined, showing ER/Golgi autoactivation and HAI-1-mediated protection from trans-autodegradation, and viral substrate range extended to SADS-CoV.","evidence":"Brefeldin A/monensin trafficking inhibitors, co-transfection and flow cytometry for HAI-1 effects; CRISPR endogenous-activation TTSP screen with pseudovirus/fusion/cleavage and camostat for SADS-CoV","pmids":["39643034","38808555"],"confidence":"High","gaps":["HAI-1-specific protection mechanism vs other TTSPs not fully resolved","SADS-CoV relevance limited to trypsin-dependent infection"]},{"year":2025,"claim":"Development of selective ketobenzothiazole peptidomimetic inhibitors provided chemical tools and a candidate antiviral strategy targeting TMPRSS13.","evidence":"Enzymatic screening of a 65-compound library against recombinant TMPRSS13, molecular modelling, cellular activity and SARS-CoV-2 pseudovirus entry inhibition","pmids":["39976239"],"confidence":"Medium","gaps":["Selectivity over related TTSPs not fully characterized","No in vivo efficacy data"]},{"year":null,"claim":"The kinase that phosphorylates the TMPRSS13 intracellular domain and the in vivo substrate repertoire underlying its epithelial barrier and oncogenic functions remain unidentified.","evidence":"","pmids":[],"confidence":"Medium","gaps":["Intracellular-domain kinase unknown","Endogenous substrates in skin/digestive epithelia beyond prostasin/HGF undefined","Physiological relevance of viral activation versus overexpression systems unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,2,7,11,13]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,10]},{"term_id":"GO:0001618","term_label":"virus receptor activity","supporting_discovery_ids":[1,3,9,12,15]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[5,13,16]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[11,16]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[16]}],"pathway":[{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[1,3,9,12,15]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[2,7,13]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[4]}],"complexes":[],"partners":["HAI-1","HAI-2","HGF","PROSTASIN","IL4I1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9BYE2","full_name":"Transmembrane protease serine 13","aliases":["Membrane-type mosaic serine protease","Mosaic serine protease"],"length_aa":586,"mass_kda":63.2,"function":"Serine protease (PubMed:20977675, PubMed:28710277, PubMed:34562451). Cleaves the proform of PRSS8/prostasin to form the active protein (PubMed:34562451). Cleaves the proform of HGF to form the active protein which promotes MAPK signaling (PubMed:20977675). Promotes the formation of the stratum corneum and subsequently the epidermal barrier in embryos (By similarity)","subcellular_location":"Cell membrane; Secreted; Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q9BYE2/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TMPRSS13","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/TMPRSS13","total_profiled":1310},"omim":[{"mim_id":"610050","title":"TRANSMEMBRANE PROTEASE, SERINE 13; TMPRSS13","url":"https://www.omim.org/entry/610050"},{"mim_id":"605124","title":"SERINE PEPTIDASE INHIBITOR, KUNITZ-TYPE, 2; SPINT2","url":"https://www.omim.org/entry/605124"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Plasma membrane","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"esophagus","ntpm":14.3},{"tissue":"skin 1","ntpm":36.8}],"url":"https://www.proteinatlas.org/search/TMPRSS13"},"hgnc":{"alias_symbol":["MSPL","MSPS"],"prev_symbol":["TMPRSS11"]},"alphafold":{"accession":"Q9BYE2","domains":[{"cath_id":"3.10.250.10","chopping":"228-314","consensus_level":"high","plddt":92.2462,"start":228,"end":314},{"cath_id":"2.40.10.10","chopping":"331-560","consensus_level":"medium","plddt":91.9763,"start":331,"end":560}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BYE2","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BYE2-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BYE2-F1-predicted_aligned_error_v6.png","plddt_mean":73.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TMPRSS13","jax_strain_url":"https://www.jax.org/strain/search?query=TMPRSS13"},"sequence":{"accession":"Q9BYE2","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BYE2.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BYE2/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BYE2"}},"corpus_meta":[{"pmid":"11433296","id":"PMC_11433296","title":"Msps/XMAP215 interacts with the centrosomal protein D-TACC to regulate microtubule behaviour.","date":"2001","source":"Nature cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/11433296","citation_count":225,"is_preprint":false},{"pmid":"11433295","id":"PMC_11433295","title":"Msps protein is localized to acentrosomal poles to ensure bipolarity of Drosophila meiotic spindles.","date":"2001","source":"Nature cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/11433295","citation_count":132,"is_preprint":false},{"pmid":"17671162","id":"PMC_17671162","title":"Proper recruitment of gamma-tubulin and D-TACC/Msps to embryonic Drosophila centrosomes requires Centrosomin Motif 1.","date":"2007","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/17671162","citation_count":91,"is_preprint":false},{"pmid":"20219906","id":"PMC_20219906","title":"Novel type II transmembrane serine proteases, MSPL and TMPRSS13, Proteolytically activate membrane fusion activity of the hemagglutinin of highly pathogenic avian influenza viruses and induce their multicycle replication.","date":"2010","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/20219906","citation_count":76,"is_preprint":false},{"pmid":"33671076","id":"PMC_33671076","title":"TMPRSS11D and TMPRSS13 Activate the SARS-CoV-2 Spike Protein.","date":"2021","source":"Viruses","url":"https://pubmed.ncbi.nlm.nih.gov/33671076","citation_count":69,"is_preprint":false},{"pmid":"25122802","id":"PMC_25122802","title":"DESC1 and MSPL activate influenza A viruses and emerging coronaviruses for host cell entry.","date":"2014","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/25122802","citation_count":67,"is_preprint":false},{"pmid":"23886730","id":"PMC_23886730","title":"Cancer therapy and fluorescence imaging using the active release of doxorubicin from MSPs/Ni-LDH folate targeting 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Recombinant soluble MSPL and TMPRSS13 preferentially cleave paired basic amino acid residues and are strongly inhibited by aprotinin, benzamidine, and Bowman-Birk trypsin inhibitor, but poorly inhibited by alpha1-antitrypsin and leupeptin.\",\n      \"method\": \"Recombinant protein expression, enzymatic assay with synthetic substrates and inhibitors, structural domain analysis from cDNA\",\n      \"journal\": \"Frontiers in bioscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro enzymatic characterization of recombinant protein, single lab, foundational characterization paper\",\n      \"pmids\": [\"17981585\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"MSPL and TMPRSS13 proteolytically cleave the hemagglutinin (HA) of highly pathogenic avian influenza (HPAI) viruses at both R/K-K-K-R cleavage site motifs, activating membrane fusion. Unlike furin, MSPL and TMPRSS13 cleave both types of HA multibasic cleavage motifs (R-X-K/R-R and K-K/R-K/T-R) in a calcium-independent manner, and their activity is suppressible by specific inhibitors. Expression of MSPL or TMPRSS13 in transfected cells enabled multicycle replication of HPAI viruses with the K-K-K-R motif.\",\n      \"method\": \"Synthetic peptide cleavage assays, transfection of full-length recombinant HPAI HA, cell-based membrane fusion assay, inhibitor studies, viral infection assay in protease-expressing cells\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple orthogonal methods (in vitro peptide cleavage, cell-based HA processing, viral replication, inhibitor suppression), single lab with rigorous controls\",\n      \"pmids\": [\"20219906\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"TMPRSS13 proteolytic activity is inhibited by hepatocyte growth factor activator inhibitor type 1 (HAI-1). A soluble form of HAI-1 containing one Kunitz domain (NK1) forms a complex with TMPRSS13 and more strongly inhibits it than the two-Kunitz-domain form (NK1LK2). TMPRSS13 converts single-chain pro-HGF to the active two-chain form in vitro, and this activity is inhibited by NK1. The resulting active HGF induces phosphorylation of c-Met and ERK, and scattered morphology in HepG2 cells.\",\n      \"method\": \"In vitro protein binding assay (complex formation), enzymatic inhibition assay, in vitro pro-HGF cleavage assay, cell-based signaling assay (c-Met/ERK phosphorylation, morphology)\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution of inhibitor-enzyme complex, in vitro substrate cleavage assay, cell-based functional validation, multiple orthogonal methods in single lab\",\n      \"pmids\": [\"20977675\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"MSPL (TMPRSS13) and DESC1 cleave and activate the spike proteins of MERS-CoV and SARS-CoV for cell-cell and virus-cell fusion. MSPL and DESC1 are expressed in human lung tissue and support spread of all influenza virus subtypes previously pandemic in humans.\",\n      \"method\": \"Cell-cell and virus-cell fusion assays, spike protein cleavage assays, expression analysis in human lung tissue, viral amplification assays\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional cell-based assays for spike cleavage and fusion, viral replication, tissue expression confirmation, single lab\",\n      \"pmids\": [\"25122802\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"TMPRSS13 (Tmprss13) is highly expressed in epithelia of the oral cavity, upper digestive tract, and skin. Genetic disruption of Tmprss13 in mice causes abnormal skin development and compromised epidermal barrier function, as measured by increased transepidermal fluid loss in newborn mice.\",\n      \"method\": \"Beta-galactosidase reporter knock-in mouse model, transepidermal water loss measurement, histological analysis\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic knockout with defined tissue expression and quantitative functional phenotype (barrier measurement), single lab with multiple methods\",\n      \"pmids\": [\"24832573\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"TMPRSS13 is a glycosylated, active protease that undergoes autoactivation through its own proteolytic activity (zymogen cleavage). Full-length active TMPRSS13 shows impaired cell-surface expression without its cognate inhibitors HAI-1 or HAI-2. Co-presence of TMPRSS13 with HAI-1 or HAI-2 mediates phosphorylation of residues in the intracellular domain, coinciding with efficient transport to the cell surface and subsequent shedding. The dominant cell-surface form of TMPRSS13 is phosphorylated, while intracellular TMPRSS13 is predominantly non-phosphorylated.\",\n      \"method\": \"Cell-surface labeling experiments, Western blotting, co-expression studies, site-directed mutagenesis (implied by activation analysis), subcellular fractionation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal approaches (surface labeling, biochemical fractionation, co-expression with inhibitors), single lab demonstrating post-translational modification linked to localization\",\n      \"pmids\": [\"28710277\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"MSPL (and TMPRSS2) promotes porcine epidemic diarrhea virus (PEDV) cell-cell fusion and virus-cell fusion. MSPL co-localizes with and cleaves the PEDV spike (S) protein, enabling multicycle PEDV replication in Vero cells in the absence of exogenous trypsin.\",\n      \"method\": \"Cell-based fusion assay, co-localization experiments, S protein cleavage assay by co-expression, viral replication assay in MSPL-expressing cells\",\n      \"journal\": \"Viruses\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-localization and S protein cleavage by co-expression, functional viral replication assay, single lab\",\n      \"pmids\": [\"28524070\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TMPRSS13 promotes breast cancer progression; siRNA-mediated silencing decreases proliferation, induces apoptosis, and attenuates invasion in human breast cancer cell lines. Genetic ablation of TMPRSS13 in the MMTV-PymT transgenic mouse model reduces overall tumor burden, growth rate, and delays tumor formation. TMPRSS13 knockdown increases prostasin protein levels, and co-immunoprecipitation and prostasin zymogen activation experiments identify prostasin as a potential TMPRSS13 substrate.\",\n      \"method\": \"siRNA knockdown, transgenic mouse tumor model (TMPRSS13 KO x MMTV-PymT), proliferation/apoptosis/invasion assays, co-immunoprecipitation, prostasin zymogen activation assay\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo KO tumor model plus in vitro mechanistic substrate identification via Co-IP and zymogen activation, multiple orthogonal methods\",\n      \"pmids\": [\"32868877\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TMPRSS13 silencing in colorectal cancer (CRC) cell lines increases apoptosis and impairs invasive potential. Transgenic overexpression of TMPRSS13 increases tolerance to apoptosis-inducing agents (paclitaxel, HA14-1), while silencing renders CRC cells more sensitive. TMPRSS13 thus promotes cell survival and resistance to drug-induced apoptosis in CRC.\",\n      \"method\": \"siRNA knockdown, transgenic overexpression, apoptosis assays, invasion assays, drug sensitivity assays (paclitaxel, HA14-1)\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — complementary gain- and loss-of-function experiments with multiple functional readouts, single lab\",\n      \"pmids\": [\"32807808\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"TMPRSS11D and TMPRSS13 enhance cellular uptake and replication of SARS-CoV-2 when exogenously expressed in ACE2-expressing HEK293T or Vero E6 cells. TMPRSS13 activates the SARS-CoV-2 spike protein to facilitate cellular entry, and this mechanism is shared with SARS-CoV-1.\",\n      \"method\": \"Exogenous expression screen of 12 TTSPs, pseudovirus entry assay, live virus replication assay in ACE2-expressing cells\",\n      \"journal\": \"Viruses\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional screen with live virus and pseudovirus validation, single lab, multiple cell systems\",\n      \"pmids\": [\"33671076\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Crystal structure of the extracellular region of human MSPL (TMPRSS13) in complex with an irreversible substrate-analog inhibitor was solved. The structure revealed three domains clustered around the C-terminal alpha-helix of the serine protease domain (SPD). The P1-Arg inserts into the S1 pocket, while P2-Lys and P4-Arg interact with a unique Asp/Glu-rich 99-loop of MSPL that determines its specificity for [R/K]-K-K-R sequences.\",\n      \"method\": \"X-ray crystallography, inhibitor complex structure determination, structural analysis of substrate-binding determinants\",\n      \"journal\": \"Life science alliance\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with bound inhibitor revealing catalytic mechanism and substrate specificity determinants, single lab with rigorous structural data\",\n      \"pmids\": [\"33820827\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"N-linked glycosylation of the serine protease (SP) domain of TMPRSS13 is critical for autoactivation, catalytic activity toward the prostasin zymogen substrate, and cell-surface trafficking; glycosylation-deficient SP domain mutants are retained in the endoplasmic reticulum. N-linked glycosylation is also a prerequisite for subsequent phosphorylation of TMPRSS13.\",\n      \"method\": \"Site-directed mutagenesis of glycosylation sites (individual and combinatorial), Western blotting, immunofluorescence/ER localization, prostasin zymogen activation assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — site-directed mutagenesis of four glycosylation sites with functional readouts for activity, localization, and phosphorylation, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"34562451\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TMPRSS13 cleaves the SARS-CoV-2 spike S2' motif (811-KPSKR-815) in a sequence-dependent manner that differs from TMPRSS2: residue K814 (preceding the scissile R815) is dispensable for TMPRSS2 activation but is favored by TMPRSS13. TMPRSS13 requires a sequence rich in K/R residues at the S2' site, while TMPRSS2 is more tolerant of variation. Swapping the SARS-CoV-2 S2' motif with that of 229E coronavirus drastically reduced TMPRSS13-mediated activation but had no effect on TMPRSS2.\",\n      \"method\": \"Site-directed mutagenesis of spike S2' motif, pseudovirus entry assay, Calu-3 cell entry experiments, comparative analysis of TMPRSS2 vs TMPRSS13 substrate specificity\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — systematic mutagenesis with pseudovirus functional assay and orthogonal cell line validation defining substrate cleavage determinants, single lab with multiple spike variants\",\n      \"pmids\": [\"35913162\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TMPRSS13 zymogen activation, cell-surface localization, shedding, and phosphorylation require proteolytic cleavage within the extracellular stem region between the transmembrane domain and the SRCR domain. This stem cleavage depends on TMPRSS13's own catalytic activity (autonomous mechanism). Mutagenesis of 10 basic residues (4 Arg, 6 Lys) in the stem region abrogated all these processing steps. Specifically, R223 (between the LDLRA and SRCR domains) was identified as an important site for stem region cleavage.\",\n      \"method\": \"Site-directed mutagenesis (individual and combinatorial basic residue mutations), Western blotting for zymogen activation and shedding, flow cytometry for cell surface expression, phosphorylation analysis\",\n      \"journal\": \"Biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — systematic site-directed mutagenesis of stem region with multiple orthogonal functional readouts (activation, surface expression, shedding, phosphorylation), single lab\",\n      \"pmids\": [\"35796294\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"IL4I1 (interleukin four-induced gene 1), a secreted enzyme, binds to TMPRSS13 on the cell surface of human lymphocytes, monocytes, and macrophages. IL4I1 and SARS-CoV-2 spike share regions of homology and compete for binding to TMPRSS13.\",\n      \"method\": \"Binding assay (identified by protein interaction screen), competition assay between IL4I1 and spike protein for TMPRSS13, pseudotyped virus entry assay, cell-surface expression analysis\",\n      \"journal\": \"Frontiers in immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — binding and competition demonstrated but details of binding assay methodology limited in abstract, single lab\",\n      \"pmids\": [\"36131918\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TMPRSS13 promotes SADS-CoV cell entry specifically at the membrane fusion step by cleaving the SADS-CoV spike protein. Both human and pig TMPRSS13 enhance cell-cell membrane fusion and spike cleavage. This activity is sensitive to the serine protease inhibitor camostat. TMPRSS13 specifically facilitates trypsin-dependent (not trypsin-independent) SADS-CoV infection.\",\n      \"method\": \"CRISPR-based endogenous activation screen of all 18 TTSP members, ectopic expression validation, pseudovirus entry assay with SADS-CoV spike, cell-cell fusion assay, spike cleavage assay, camostat inhibitor treatment\",\n      \"journal\": \"Journal of medical virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — systematic CRISPR screen followed by multiple orthogonal validation methods (ectopic expression, pseudovirus entry, fusion assay, inhibitor), single lab\",\n      \"pmids\": [\"38808555\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TMPRSS13 undergoes intracellular autoactivation in the endoplasmic reticulum and Golgi apparatus. HAI-1 facilitates TMPRSS13 activation, protects it from autodegradation (trans-autodegradation), and stabilizes its cell-surface expression—distinct from its effect on HPN and TMPRSS2. Active TMPRSS13 is subject to trans-autodegradation that reduces cell-surface expression.\",\n      \"method\": \"Site-directed mutagenesis, Western blotting, flow cytometry, immunostaining, brefeldin A and monensin treatment (Golgi/ER trafficking inhibitors), co-transfection assays\",\n      \"journal\": \"Life sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple pharmacological and genetic approaches to dissect intracellular activation and trafficking, single lab\",\n      \"pmids\": [\"39643034\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Ketobenzothiazole-based peptidomimetic inhibitors were developed for TMPRSS13 through screening a 65-compound library against recombinant active TMPRSS13. Lead inhibitor N-0430 achieved low nanomolar affinity toward TMPRSS13 in a cellular context. Molecular modelling identified key molecular determinants of TMPRSS13 inhibition. N-0430 blocked TMPRSS13-dependent SARS-CoV-2 pseudovirus cell entry.\",\n      \"method\": \"In vitro enzymatic screening of compound library against recombinant TMPRSS13, molecular modelling, cellular TMPRSS13 activity assay, SARS-CoV-2 pseudovirus entry inhibition assay\",\n      \"journal\": \"Journal of enzyme inhibition and medicinal chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro enzymatic screening with cellular validation and pseudovirus functional assay, single lab\",\n      \"pmids\": [\"39976239\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TMPRSS13 (MSPL) is a type II transmembrane serine protease that undergoes intracellular autoactivation via autonomous stem-region cleavage, is regulated by N-linked glycosylation (required for activation, catalytic activity, and ER-to-surface trafficking) and phosphorylation of its intracellular domain (promoted by HAI-1/HAI-2 and linked to cell-surface localization and shedding), preferentially cleaves polybasic R/K-K-K-R sequences, activates pro-HGF and the prostasin zymogen as endogenous substrates, is inhibited by HAI-1 through a Kunitz domain interaction, promotes epidermal barrier formation and breast/colorectal cancer progression, and serves as a host cell activating protease for highly pathogenic influenza HA proteins, SARS-CoV-1/2 spike, MERS-CoV spike, PEDV S, and SADS-CoV spike by cleaving multibasic cleavage motifs to enable membrane fusion and viral entry.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TMPRSS13 (MSPL) is a type II transmembrane serine protease that governs pericellular proteolysis at epithelial surfaces and serves as a host activating protease for diverse viral envelope glycoproteins [#0, #1]. Its catalytic domain preferentially cleaves polybasic [R/K]-K-K-R motifs, a specificity dictated by a unique Asp/Glu-rich 99-loop that engages the P2-Lys and P4-Arg of the substrate while the P1-Arg inserts into the S1 pocket [#0, #10]. Maturation proceeds by autonomous, intracellular autoactivation in the ER and Golgi via cleavage within the extracellular stem region, with R223 a critical scissile site; this processing is required for catalytic activity, surface trafficking, and shedding [#13, #16]. N-linked glycosylation of the protease domain is a prerequisite for autoactivation, catalytic activity, and ER-to-surface export, and is itself required for downstream phosphorylation of the intracellular domain [#11]. The cognate Kunitz-type inhibitors HAI-1 and HAI-2 both restrain catalytic activity and paradoxically promote its phosphorylation, surface localization, and stability by protecting TMPRSS13 from trans-autodegradation [#2, #5, #16]. Endogenous substrates include pro-HGF, whose activation triggers c-Met/ERK signaling, and the prostasin zymogen [#2, #7]. Physiologically, TMPRSS13 is expressed in oral, digestive, and skin epithelia and is required for epidermal barrier formation, and it drives breast and colorectal cancer progression by supporting proliferation, invasion, and resistance to apoptosis [#4, #7, #8]. As a host protease, TMPRSS13 cleaves the multibasic activation motifs of highly pathogenic influenza HA and the spike proteins of SARS-CoV-1/2, MERS-CoV, PEDV, and SADS-CoV to enable membrane fusion and viral entry, with S2' cleavage requiring a K/R-rich motif distinct from the determinants used by TMPRSS2 [#1, #3, #9, #12, #15].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Establishing that MSPL/TMPRSS13 are type II transmembrane serine proteases with a defined domain architecture and basic-residue cleavage preference set the foundation for all subsequent substrate work.\",\n      \"evidence\": \"Recombinant soluble protein expression with synthetic substrate and inhibitor profiling, plus cDNA domain analysis\",\n      \"pmids\": [\"17981585\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No physiological substrate or in vivo role identified\", \"Specificity defined only by synthetic peptides, not endogenous proteins\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"The first physiological and pathophysiological substrates emerged: TMPRSS13 activates influenza HA multibasic motifs and converts pro-HGF to active HGF, linking the protease to viral entry and growth-factor signaling.\",\n      \"evidence\": \"Peptide cleavage, full-length HA processing, cell-based fusion and viral replication assays; in vitro pro-HGF cleavage with c-Met/ERK readout; HAI-1 inhibition assays\",\n      \"pmids\": [\"20219906\", \"20977675\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Endogenous (non-overexpression) contribution to viral spread not established\", \"HGF activation shown in vitro/cell lines, not in tissue\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Genetic and tissue evidence established a physiological role in epithelial barrier biology and extended viral activation to coronaviruses.\",\n      \"evidence\": \"Tmprss13 reporter knock-in mouse with transepidermal water loss and histology; spike cleavage and fusion assays for MERS-CoV/SARS-CoV in lung-expressed protease\",\n      \"pmids\": [\"24832573\", \"25122802\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Endogenous epidermal substrate driving barrier defect not identified\", \"Coronavirus activation tested largely by overexpression\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defining the autoactivation and HAI-dependent regulatory logic explained how an active intracellular protease reaches and is controlled at the cell surface.\",\n      \"evidence\": \"Surface labeling, subcellular fractionation, co-expression with HAI-1/HAI-2, phosphorylation analysis\",\n      \"pmids\": [\"28710277\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Kinase responsible for intracellular-domain phosphorylation not identified\", \"Functional consequence of shedding unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Loss- and gain-of-function studies established TMPRSS13 as a driver of breast and colorectal cancer and identified prostasin as an endogenous substrate.\",\n      \"evidence\": \"siRNA knockdown, transgenic KO x MMTV-PymT tumor model, proliferation/apoptosis/invasion assays, Co-IP and prostasin zymogen activation; CRC drug-sensitivity assays\",\n      \"pmids\": [\"32868877\", \"32807808\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Prostasin identified by Co-IP/zymogen assay without reciprocal validation in vivo\", \"Mechanism linking proteolysis to apoptosis resistance undefined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Structural and post-translational studies resolved the molecular basis of substrate specificity and the requirement of glycosylation for maturation, while expanding viral substrates to SARS-CoV-2.\",\n      \"evidence\": \"Crystal structure with substrate-analog inhibitor; glycosylation-site mutagenesis with activity/localization/phosphorylation readouts; TTSP expression screen with pseudovirus and live SARS-CoV-2 entry\",\n      \"pmids\": [\"33820827\", \"34562451\", \"33671076\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Structure captures inhibitor complex, not native substrate or full-length protein\", \"SARS-CoV-2 entry assessed under exogenous overexpression\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Mechanistic dissection located the autoactivation cleavage to the extracellular stem region (R223), defined a K/R-rich S2' cleavage determinant distinct from TMPRSS2, and identified IL4I1 as a surface-binding partner competing with spike.\",\n      \"evidence\": \"Stem-region basic-residue mutagenesis with activation/surface/shedding/phosphorylation readouts; spike S2' mutagenesis with pseudovirus and Calu-3 entry; IL4I1 binding and spike-competition assays\",\n      \"pmids\": [\"35796294\", \"35913162\", \"36131918\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Physiological role of IL4I1-TMPRSS13 interaction unresolved\", \"Whether stem cleavage occurs in cis or trans not fully established\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Compartmental and stability mechanisms were refined, showing ER/Golgi autoactivation and HAI-1-mediated protection from trans-autodegradation, and viral substrate range extended to SADS-CoV.\",\n      \"evidence\": \"Brefeldin A/monensin trafficking inhibitors, co-transfection and flow cytometry for HAI-1 effects; CRISPR endogenous-activation TTSP screen with pseudovirus/fusion/cleavage and camostat for SADS-CoV\",\n      \"pmids\": [\"39643034\", \"38808555\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"HAI-1-specific protection mechanism vs other TTSPs not fully resolved\", \"SADS-CoV relevance limited to trypsin-dependent infection\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Development of selective ketobenzothiazole peptidomimetic inhibitors provided chemical tools and a candidate antiviral strategy targeting TMPRSS13.\",\n      \"evidence\": \"Enzymatic screening of a 65-compound library against recombinant TMPRSS13, molecular modelling, cellular activity and SARS-CoV-2 pseudovirus entry inhibition\",\n      \"pmids\": [\"39976239\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Selectivity over related TTSPs not fully characterized\", \"No in vivo efficacy data\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The kinase that phosphorylates the TMPRSS13 intracellular domain and the in vivo substrate repertoire underlying its epithelial barrier and oncogenic functions remain unidentified.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Intracellular-domain kinase unknown\", \"Endogenous substrates in skin/digestive epithelia beyond prostasin/HGF undefined\", \"Physiological relevance of viral activation versus overexpression systems unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 2, 7, 11, 13]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 10]},\n      {\"term_id\": \"GO:0001618\", \"supporting_discovery_ids\": [1, 3, 9, 12, 15]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [5, 13, 16]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [11, 16]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [16]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [1, 3, 9, 12, 15]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [2, 7, 13]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"HAI-1\", \"HAI-2\", \"HGF\", \"prostasin\", \"IL4I1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win"}}