{"gene":"PRSS21","run_date":"2026-06-10T06:43:36","timeline":{"discoveries":[{"year":2002,"finding":"PRSS21 (TESP5/testisin/esp-1) is a GPI-anchored serine protease on the sperm cell surface. When HEK293 cells were transformed with an expression plasmid carrying the entire PRSS21 protein-coding region, the recombinant protein was released from the cell membrane by treatment with Bacillus cereus phosphatidylinositol-specific phospholipase C, confirming GPI-anchoring. The 42- and 41-kDa forms were selectively included into Triton X-100-insoluble lipid raft microdomains of sperm membranes. Enzymatic properties of recombinant TESP5 were similar to but distinct from rat acrosin and pancreatic trypsin in substrate specificity and sensitivity to serine protease inhibitors.","method":"Expression plasmid transfection in HEK293 cells, phospholipase C treatment, immunochemical analysis, Triton X-100 fractionation, enzymatic substrate specificity assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — recombinant protein expression with PI-PLC release assay directly confirms GPI anchor; lipid raft fractionation and enzymatic characterization provide multiple orthogonal methods in one study","pmids":["11861648"],"is_preprint":false},{"year":1998,"finding":"PRSS21 (ESP-1) encodes a membrane-type serine protease with a signal peptide of 18 amino acids, a propeptide of 23 amino acids, a catalytic domain containing the canonical serine protease catalytic triad (His, Asp, Ser), and a C-terminal hydrophobic stretch indicating membrane anchoring. The gene is most abundantly expressed in testis and prostate, with expression also in eosinophils (but not neutrophils), mononuclear cells, lung, spleen, and pancreas.","method":"cDNA cloning from human eosinophils, deduced amino acid sequence analysis, tissue distribution by Northern/RT-PCR","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — initial cloning and sequence analysis identifying catalytic triad from a single lab; tissue distribution by expression analysis without functional validation of enzymatic activity","pmids":["9826525"],"is_preprint":false},{"year":1999,"finding":"The ESP-1/PRSS21 gene spans approximately 4.6 kb, consists of 6 exons and 5 introns, and maps to chromosome 16p13.3. A new splicing variant was identified from HeLa cell cDNA. Dual-luciferase reporter analysis revealed that a GC-rich region between nucleotide positions -106 and -189 (containing one AP-1/Sp-1 binding site) is responsible for minimum promoter activity in HeLa cells. The transcription initiation site is at position -106 (residue G).","method":"BAC library cloning, radiation hybrid mapping, FISH, RNase protection, primer extension, dual-luciferase reporter assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — luciferase reporter assay directly tests promoter activity; multiple mapping methods; single lab","pmids":["10600542"],"is_preprint":false},{"year":2000,"finding":"The human PRSS21 gene is approximately 4.5 kb, contains 6 exons and 5 introns, and localizes to chromosome 16p13.3 between microsatellite marker D16S246 and radiation hybrid breakpoint CY23HA. Two known isoforms of testisin are generated by alternative pre-mRNA splicing. The 5'-flanking region lacks a TATA box but contains a CCAAT sequence, a CpG island, and consensus elements for Sp1, AP1, and testis-specific transcription factors. Testisin is expressed in premeiotic testicular germ cells but not in testicular tumor cell lines, and is aberrantly expressed in some non-testis tumor cell lines.","method":"Genomic library screening, sequence analysis, radiation hybrid mapping, Northern blot, RT-PCR in tumor cell lines","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct gene characterization with multiple methods; single lab; expression data without functional readout","pmids":["11004480"],"is_preprint":false},{"year":2001,"finding":"The murine Prss21 gene has six exons and five introns spanning approximately 5 kb, localizes to murine chromosome 17A3.3-B (syntenic with human 16p13.3), and encodes a 324-amino acid protein with an N-terminal signal sequence, a pro-region, a 251-amino acid catalytic domain with trypsin-like specificity, and a C-terminal hydrophobic GPI-anchor extension. Immunostaining localized murine Testisin to the cytoplasm and plasma membrane of round and elongating spermatids. mRNA expression onset at approximately day 18 post-birth corresponds to the appearance of spermatids, indicating temporal regulation during spermatogenesis.","method":"Genomic cloning, sequence analysis, Northern blot, immunostaining of mouse testis sections","journal":"European journal of biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct immunolocalization in testis tissue; gene structure analysis; single lab with multiple complementary methods","pmids":["11231276"],"is_preprint":false},{"year":2005,"finding":"Hypermethylation of a 385 bp 5'-CpG island in the PRSS21 (testisin) promoter silences its expression in 100% of testicular germ cell tumors (8/8) and multiple tumor cell lines, as shown by bisulfite sequencing. Treatment of testisin-negative cell lines with demethylating agents and/or histone deacetylase inhibitor reactivated testisin expression. Stable expression of testisin in the testisin-negative Tera-2 testicular cancer line suppressed anchorage-dependent growth and tumor formation in SCID mice, establishing a tumor suppressor function.","method":"Bisulfite sequencing, demethylating agent treatment, HDAC inhibitor treatment, RT-PCR, stable transfection, anchorage-dependent growth assay, SCID mouse xenograft model","journal":"British journal of cancer","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (bisulfite sequencing, pharmacological reactivation, stable transfection with in vivo tumor suppression); functional tumor suppressor role directly demonstrated","pmids":["15685234"],"is_preprint":false},{"year":2005,"finding":"PRSS21 and related serine proteases (tryptase 5/Prss32, pancreasin/Prss27, testis serine protease-1) are inserted into plasma membranes via glycosylphosphatidylinositol (GPI) anchors, as demonstrated by phosphatidylinositol-specific phospholipase C release, and are consequently targeted to lipid rafts.","method":"PI-PLC treatment, cell surface release assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — PI-PLC release assay directly confirms GPI anchoring; single lab; corroborates earlier PMID:11861648 finding","pmids":["16143303"],"is_preprint":false},{"year":2008,"finding":"Prss21-null epididymal sperm penetrate the zona pellucida (ZP) at very low rates in vitro, due to reduced ability to bind the ZP and undergo ZP-induced acrosome reaction. Sperm-egg fusion in vitro was also severely impaired. Importantly, the reduced fertility of Prss21-null epididymal sperm was rescued by exposure to the uterine microenvironment (in vivo passage through uterus or in vitro treatment with uterine fluids), demonstrating that PRSS21's proteolytic function in ZP penetration can be compensated by uterine factors.","method":"Prss21 knockout mouse model, in vitro fertilization assay, ZP binding assay, acrosome reaction assay, uterine fluid treatment experiment","journal":"Genes to cells : devoted to molecular & cellular mechanisms","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO mouse model with defined cellular phenotypes; multiple orthogonal functional assays (ZP binding, acrosome reaction, sperm-egg fusion, uterine fluid rescue); single lab but rigorous","pmids":["18754795"],"is_preprint":false},{"year":2009,"finding":"PRSS21-deficient spermatozoa show decreased motility, angulated and curled tails, fragile necks, and dramatically increased susceptibility to decapitation during epididymal transit. Histological and electron microscopic analyses showed increased curling and detachment of tails as spermatozoa transit from corpus to cauda epididymis. Cauda epididymal spermatozoa deficient in PRSS21 fail to mount a swelling response to hypotonic conditions, indicating impaired osmotic regulatory ability. These defects identify PRSS21 as a novel proteolytic factor directing epididymal sperm maturation and fertilizing ability.","method":"PRSS21 knockout mouse model, light and electron microscopy, sperm motility analysis, hypotonic swelling test","journal":"Biology of reproduction","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO mouse with multiple structural and functional phenotypic readouts; electron microscopy validation; multiple independent assays in one study","pmids":["19571264"],"is_preprint":false},{"year":2010,"finding":"Double-knockout mice lacking both ACR (acrosin) and PRSS21 are subfertile in vivo, and their sperm are unable to undergo acrosomal exocytosis on the zona pellucida surface or traverse the ZP in vitro, and are also defective in penetrating the cumulus matrix. Artificial insemination directly into the uterus partially rescued fertilization, as did the presence of uterine fluids in vitro. This demonstrates that the trypsin-like protease activity of ACR and PRSS21 together is essential for sperm penetration through cumulus matrix and ZP in vitro, while female reproductive tract factors can partially compensate in vivo.","method":"Double-knockout mouse generation (ACR and PRSS21), in vitro fertilization assay, acrosome reaction assay on ZP, cumulus penetration assay, artificial insemination experiment","journal":"Biology of reproduction","confidence":"High","confidence_rationale":"Tier 2 / Strong — double-KO epistasis experiment with multiple orthogonal functional assays; directly tests pathway position of PRSS21 relative to ACR in fertilization","pmids":["20484738"],"is_preprint":false},{"year":2018,"finding":"Testisin (PRSS21) surface expression on stallion spermatozoa increases significantly upon capacitation and further increases after acrosome reaction, with localization to the equatorial region of the sperm head. Testisin is also found in epididymal luminal fluid and epithelial cells. Blue Native PAGE and co-immunoprecipitation followed by mass spectrometry revealed that testisin forms several high-molecular-weight multiprotein complexes and interacts with zona pellucida-binding proteins including ZPBP, ZAN, acrosin, multiple heat-shock proteins, and components of the TCP1 complex, indicating participation in the ZP-binding complex.","method":"Live cell immunofluorescence, flow cytometry, immunohistochemistry, Blue Native PAGE, co-immunoprecipitation, mass spectrometry","journal":"Andrology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP with MS identification of interacting partners; live cell localization with functional context; multiple orthogonal methods in single study","pmids":["30549223"],"is_preprint":false},{"year":2019,"finding":"In a murine xenograft model of ovarian intraperitoneal tumor metastasis, increased tumor testisin expression inhibited intraperitoneal tumor seeding, colonization, ascites accumulation, and metastatic tumor burden in a manner dependent on catalytically active testisin. Testisin activity suppresses the synthesis and secretion of pro-angiogenic angiopoietins ANG2 and ANGPTL4 (which promote vascular leak and edema). Gene profiling and mechanistic studies support a model wherein testisin activates protease-activated receptor-2 (PAR-2) as a substrate to antagonize pro-angiogenic angiopoietins that modulate vascular permeability.","method":"Murine xenograft model with testisin-overexpressing ovarian cancer cells, catalytic mutant controls, gene expression profiling, mechanistic studies of ANG2/ANGPTL4 secretion","journal":"Journal of molecular medicine (Berlin, Germany)","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo model with catalytic-mutant control establishing mechanism dependence; substrate (PAR-2) and downstream effectors (ANG2, ANGPTL4) identified; multiple orthogonal methods","pmids":["30911775"],"is_preprint":false},{"year":2020,"finding":"Testisin (PRSS21)-deficient mice (Prss21-/-) show a substantially increased incidence and severity of hemorrhages during corpus luteal development, associated with increased vascular leakiness (greater Evans blue dye extravasation). siRNA knockdown of testisin in microvascular endothelial cells impaired reorganization and tubule-like formation on Matrigel and increased paracellular permeability to FITC-albumin, associated with decreased VE-cadherin expression and increased phospho(Tyr658)-VE-cadherin levels. Tight junction proteins occludin, claudin-5, and ZO-1 were unaffected. These data identify testisin as a novel regulator of VE-cadherin-mediated endothelial adherens junctions during angiogenesis.","method":"Prss21-/- mouse model, Evans blue extravasation assay, siRNA knockdown in endothelial cells, Matrigel tubule formation assay, FITC-albumin permeability assay, Western blot for VE-cadherin and phospho-VE-cadherin, live cell imaging","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO mouse combined with siRNA knockdown and multiple in vitro functional assays; specific molecular mechanism (VE-cadherin phosphorylation) identified; multiple orthogonal methods","pmids":["32511276"],"is_preprint":false},{"year":2024,"finding":"SPEM2 interacts with PRSS21 (testisin) in epididymal sperm and is required for its processing and maturation. Co-immunoprecipitation demonstrated SPEM2 interaction with PRSS21 along with ZPBP, PRSS54, PRSS55, ADAM2, and ADAM3. SPEM2 deficiency in mice resulted in decreased levels of processed/mature PRSS21 in epididymal sperm.","method":"Co-immunoprecipitation, Western blot in Spem2 knockout mice","journal":"Cellular and molecular life sciences : CMLS","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP identifies SPEM2 as a PRSS21 interaction partner; KO model shows dependency of PRSS21 maturation on SPEM2; single lab, limited mechanistic depth on PRSS21 specifically","pmids":["38421455"],"is_preprint":false},{"year":2019,"finding":"Fluoride exposure in rats downregulated PRSS21 expression (both mRNA and protein) in the epididymis in a dose-dependent manner, which was associated with reduced sperm ability to break down the egg cumulus cell layer. Immunofluorescence confirmed altered localization of PRSS21 protein in fluoride-treated epididymis.","method":"In vivo fluoride exposure in rats, Western blot, RT-PCR, immunofluorescence, sperm-egg cumulus penetration assay","journal":"Journal of agricultural and food chemistry","confidence":"Low","confidence_rationale":"Tier 3 / Weak — correlative downregulation of PRSS21 by fluoride with functional phenotype; no direct manipulation of PRSS21 itself; single lab, single model","pmids":["31008594"],"is_preprint":false}],"current_model":"PRSS21 (testisin/ESP-1) is a GPI-anchored serine protease with trypsin-like activity that localizes to lipid rafts on the sperm cell surface and in microvascular endothelial cells; in spermatozoa it is required for epididymal maturation, osmotic regulation, ZP binding, acrosome reaction, and cumulus/ZP penetration during fertilization (redundantly with acrosin), forms multiprotein complexes with ZP-binding proteins, and its processing depends on SPEM2; in ovarian cancer and endothelial cells, catalytically active testisin activates PAR-2 to suppress pro-angiogenic ANG2 and ANGPTL4 secretion and maintains VE-cadherin-mediated vascular integrity; loss of PRSS21 expression in testicular germ cell tumors is caused by CpG island hypermethylation and histone deacetylation, and its re-expression suppresses tumor growth."},"narrative":{"mechanistic_narrative":"PRSS21 (testisin/ESP-1) is a GPI-anchored, trypsin-like serine protease that operates in two distinct biological settings: male germ cell maturation and fertilization, and endothelial/vascular regulation [PMID:11861648, PMID:18754795, PMID:30911775]. The mature protein carries a canonical His-Asp-Ser catalytic triad and a C-terminal hydrophobic GPI-anchor extension that targets it to Triton X-100-insoluble lipid raft microdomains of the cell surface [PMID:11861648, PMID:9826525]. In spermatozoa, testisin is required for epididymal sperm maturation, maintaining tail integrity and osmotic regulatory capacity during epididymal transit, and for fertilization steps including zona pellucida binding, ZP-induced acrosome reaction, and cumulus/ZP penetration; this proteolytic function acts redundantly with acrosin and can be compensated by uterine factors in vivo [PMID:18754795, PMID:19571264, PMID:20484738]. On the sperm surface it assembles into high-molecular-weight multiprotein complexes with zona pellucida-binding proteins including ZPBP, ZAN, and acrosin, and its processing to the mature form depends on SPEM2 [PMID:30549223, PMID:38421455]. In ovarian cancer and microvascular endothelial cells, catalytically active testisin activates the receptor PAR-2 to suppress secretion of pro-angiogenic ANG2 and ANGPTL4 and maintains VE-cadherin-mediated adherens junctions, thereby restraining vascular leak, tumor seeding, and metastasis [PMID:30911775, PMID:32511276]. In testicular germ cell tumors, PRSS21 expression is silenced by 5'-CpG island hypermethylation and histone deacetylation, and its re-expression suppresses anchorage-dependent growth and xenograft tumor formation, defining a tumor suppressor activity [PMID:15685234].","teleology":[{"year":1998,"claim":"Initial cloning established PRSS21 as a membrane-type serine protease with the molecular hallmarks needed for catalytic activity and membrane attachment, framing it as a candidate protease in testis biology.","evidence":"cDNA cloning from human eosinophils with deduced sequence and tissue distribution analysis","pmids":["9826525"],"confidence":"Medium","gaps":["Enzymatic activity not functionally validated","GPI anchoring inferred from sequence, not demonstrated","No cellular function assigned"]},{"year":2000,"claim":"Genomic characterization mapped the gene and promoter and first noted that testisin is expressed in premeiotic germ cells but lost in testicular tumor cell lines, hinting at a cancer-relevant expression pattern.","evidence":"Genomic library screening, radiation hybrid mapping, and RT-PCR across tumor cell lines","pmids":["11004480","10600542"],"confidence":"Medium","gaps":["Mechanism of tumor-associated silencing unknown","No functional consequence of expression loss tested"]},{"year":2001,"claim":"Murine gene characterization tied PRSS21 expression to the appearance of spermatids during spermatogenesis, localizing it to spermatid cytoplasm and plasma membrane and establishing a temporally regulated germ-cell role.","evidence":"Genomic cloning and immunostaining of mouse testis sections across postnatal development","pmids":["11231276"],"confidence":"Medium","gaps":["Function in sperm not tested","GPI anchor not biochemically confirmed at this stage"]},{"year":2002,"claim":"Biochemical work confirmed that PRSS21 is GPI-anchored and partitions into sperm lipid rafts, and that its enzymatic specificity is trypsin-like but distinct from acrosin and pancreatic trypsin, resolving its surface topology and catalytic identity.","evidence":"Recombinant expression in HEK293 cells with PI-PLC release, Triton X-100 raft fractionation, and substrate specificity assays","pmids":["11861648","16143303"],"confidence":"High","gaps":["Physiological substrates not identified","Catalytic role in fertilization not yet demonstrated"]},{"year":2005,"claim":"The cause and consequence of PRSS21 loss in cancer were established: epigenetic silencing via CpG hypermethylation and histone deacetylation, with re-expression suppressing tumor growth, defining a tumor suppressor function.","evidence":"Bisulfite sequencing, demethylating/HDAC inhibitor reactivation, stable transfection, and SCID mouse xenografts","pmids":["15685234"],"confidence":"High","gaps":["Catalytic dependence of tumor suppression not tested here","Downstream effectors of growth suppression unknown"]},{"year":2010,"claim":"Knockout and double-knockout studies defined the cellular role of PRSS21 in fertilization, showing it is required for epididymal sperm structural integrity and osmotic regulation and, redundantly with acrosin, for ZP and cumulus penetration, with uterine factors compensating in vivo.","evidence":"Prss21 single- and Acr/Prss21 double-knockout mice with IVF, ZP binding, acrosome reaction, cumulus penetration, hypotonic swelling, and uterine fluid rescue assays","pmids":["18754795","19571264","20484738"],"confidence":"High","gaps":["Direct proteolytic substrates on sperm/egg not identified","Molecular basis of uterine compensation unknown"]},{"year":2018,"claim":"Proteomic analysis placed testisin within the sperm ZP-binding machinery, showing capacitation/acrosome-dependent surface dynamics and assembly into multiprotein complexes with ZP-binding proteins.","evidence":"Live cell immunofluorescence, flow cytometry, Blue Native PAGE, and Co-IP/mass spectrometry on stallion sperm","pmids":["30549223"],"confidence":"High","gaps":["Direct vs indirect nature of interactions not resolved","Functional necessity of complex assembly not tested"]},{"year":2020,"claim":"A vascular function was established: testisin maintains endothelial barrier integrity through VE-cadherin, with loss increasing vascular leak and decreasing VE-cadherin while elevating its inhibitory phosphorylation, and a parallel oncology study linked catalytically active testisin to PAR-2-mediated suppression of pro-angiogenic angiopoietins.","evidence":"Prss21-/- mice, endothelial siRNA knockdown, Matrigel tubule and FITC-albumin permeability assays, VE-cadherin Western blots; plus xenograft model with catalytic-mutant controls and ANG2/ANGPTL4 profiling","pmids":["32511276","30911775"],"confidence":"High","gaps":["Direct demonstration that testisin cleaves PAR-2 on endothelium incomplete","Connection between PAR-2 activation and VE-cadherin phosphorylation not fully mapped"]},{"year":2024,"claim":"An upstream processing requirement was identified, showing SPEM2 interacts with PRSS21 and is needed for its maturation in epididymal sperm, embedding testisin in a broader sperm protein-processing network.","evidence":"Co-immunoprecipitation and Western blot in Spem2 knockout mice","pmids":["38421455"],"confidence":"Medium","gaps":["Direct vs indirect SPEM2-PRSS21 interaction unresolved","Protease responsible for PRSS21 processing not identified","Limited mechanistic depth on PRSS21 specifically"]},{"year":null,"claim":"The endogenous physiological substrates of testisin on the sperm surface and the precise enzymatic steps linking its activity to ZP/cumulus penetration and to endothelial barrier maintenance remain undefined.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No direct sperm-side proteolytic substrate identified","Mechanism linking PAR-2 cleavage to VE-cadherin stabilization not fully resolved","Structural model of testisin and its complexes absent"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,11]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,7]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,4,6]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[4]}],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[7,8,9]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[5,11]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[11,12]}],"complexes":["sperm zona pellucida-binding complex"],"partners":["ZPBP","ZAN","ACR","SPEM2","ADAM2","ADAM3","PRSS54","PRSS55"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9Y6M0","full_name":"Testisin","aliases":["Eosinophil serine protease 1","ESP-1","Serine protease 21"],"length_aa":314,"mass_kda":34.9,"function":"Could regulate proteolytic events associated with testicular germ cell maturation","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q9Y6M0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PRSS21","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/PRSS21","total_profiled":1310},"omim":[{"mim_id":"609341","title":"TRYPTASE, GAMMA-1; TPSG1","url":"https://www.omim.org/entry/609341"},{"mim_id":"608159","title":"PROTEASE, SERINE, 21; PRSS21","url":"https://www.omim.org/entry/608159"},{"mim_id":"608018","title":"PROTEASE, SERINE, 27; PRSS27","url":"https://www.omim.org/entry/608018"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"},{"location":"Mid piece","reliability":"Approved"},{"location":"Principal piece","reliability":"Approved"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"testis","ntpm":81.8}],"url":"https://www.proteinatlas.org/search/PRSS21"},"hgnc":{"alias_symbol":["ESP-1","TEST1"],"prev_symbol":[]},"alphafold":{"accession":"Q9Y6M0","domains":[{"cath_id":"2.40.10.10","chopping":"46-289","consensus_level":"medium","plddt":94.0377,"start":46,"end":289}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y6M0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y6M0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y6M0-F1-predicted_aligned_error_v6.png","plddt_mean":84.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PRSS21","jax_strain_url":"https://www.jax.org/strain/search?query=PRSS21"},"sequence":{"accession":"Q9Y6M0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9Y6M0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9Y6M0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y6M0"}},"corpus_meta":[{"pmid":"26861414","id":"PMC_26861414","title":"Maternal 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When HEK293 cells were transformed with an expression plasmid carrying the entire PRSS21 protein-coding region, the recombinant protein was released from the cell membrane by treatment with Bacillus cereus phosphatidylinositol-specific phospholipase C, confirming GPI-anchoring. The 42- and 41-kDa forms were selectively included into Triton X-100-insoluble lipid raft microdomains of sperm membranes. Enzymatic properties of recombinant TESP5 were similar to but distinct from rat acrosin and pancreatic trypsin in substrate specificity and sensitivity to serine protease inhibitors.\",\n      \"method\": \"Expression plasmid transfection in HEK293 cells, phospholipase C treatment, immunochemical analysis, Triton X-100 fractionation, enzymatic substrate specificity assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — recombinant protein expression with PI-PLC release assay directly confirms GPI anchor; lipid raft fractionation and enzymatic characterization provide multiple orthogonal methods in one study\",\n      \"pmids\": [\"11861648\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"PRSS21 (ESP-1) encodes a membrane-type serine protease with a signal peptide of 18 amino acids, a propeptide of 23 amino acids, a catalytic domain containing the canonical serine protease catalytic triad (His, Asp, Ser), and a C-terminal hydrophobic stretch indicating membrane anchoring. The gene is most abundantly expressed in testis and prostate, with expression also in eosinophils (but not neutrophils), mononuclear cells, lung, spleen, and pancreas.\",\n      \"method\": \"cDNA cloning from human eosinophils, deduced amino acid sequence analysis, tissue distribution by Northern/RT-PCR\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — initial cloning and sequence analysis identifying catalytic triad from a single lab; tissue distribution by expression analysis without functional validation of enzymatic activity\",\n      \"pmids\": [\"9826525\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"The ESP-1/PRSS21 gene spans approximately 4.6 kb, consists of 6 exons and 5 introns, and maps to chromosome 16p13.3. A new splicing variant was identified from HeLa cell cDNA. Dual-luciferase reporter analysis revealed that a GC-rich region between nucleotide positions -106 and -189 (containing one AP-1/Sp-1 binding site) is responsible for minimum promoter activity in HeLa cells. The transcription initiation site is at position -106 (residue G).\",\n      \"method\": \"BAC library cloning, radiation hybrid mapping, FISH, RNase protection, primer extension, dual-luciferase reporter assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — luciferase reporter assay directly tests promoter activity; multiple mapping methods; single lab\",\n      \"pmids\": [\"10600542\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"The human PRSS21 gene is approximately 4.5 kb, contains 6 exons and 5 introns, and localizes to chromosome 16p13.3 between microsatellite marker D16S246 and radiation hybrid breakpoint CY23HA. Two known isoforms of testisin are generated by alternative pre-mRNA splicing. The 5'-flanking region lacks a TATA box but contains a CCAAT sequence, a CpG island, and consensus elements for Sp1, AP1, and testis-specific transcription factors. Testisin is expressed in premeiotic testicular germ cells but not in testicular tumor cell lines, and is aberrantly expressed in some non-testis tumor cell lines.\",\n      \"method\": \"Genomic library screening, sequence analysis, radiation hybrid mapping, Northern blot, RT-PCR in tumor cell lines\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct gene characterization with multiple methods; single lab; expression data without functional readout\",\n      \"pmids\": [\"11004480\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"The murine Prss21 gene has six exons and five introns spanning approximately 5 kb, localizes to murine chromosome 17A3.3-B (syntenic with human 16p13.3), and encodes a 324-amino acid protein with an N-terminal signal sequence, a pro-region, a 251-amino acid catalytic domain with trypsin-like specificity, and a C-terminal hydrophobic GPI-anchor extension. Immunostaining localized murine Testisin to the cytoplasm and plasma membrane of round and elongating spermatids. mRNA expression onset at approximately day 18 post-birth corresponds to the appearance of spermatids, indicating temporal regulation during spermatogenesis.\",\n      \"method\": \"Genomic cloning, sequence analysis, Northern blot, immunostaining of mouse testis sections\",\n      \"journal\": \"European journal of biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct immunolocalization in testis tissue; gene structure analysis; single lab with multiple complementary methods\",\n      \"pmids\": [\"11231276\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Hypermethylation of a 385 bp 5'-CpG island in the PRSS21 (testisin) promoter silences its expression in 100% of testicular germ cell tumors (8/8) and multiple tumor cell lines, as shown by bisulfite sequencing. Treatment of testisin-negative cell lines with demethylating agents and/or histone deacetylase inhibitor reactivated testisin expression. Stable expression of testisin in the testisin-negative Tera-2 testicular cancer line suppressed anchorage-dependent growth and tumor formation in SCID mice, establishing a tumor suppressor function.\",\n      \"method\": \"Bisulfite sequencing, demethylating agent treatment, HDAC inhibitor treatment, RT-PCR, stable transfection, anchorage-dependent growth assay, SCID mouse xenograft model\",\n      \"journal\": \"British journal of cancer\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (bisulfite sequencing, pharmacological reactivation, stable transfection with in vivo tumor suppression); functional tumor suppressor role directly demonstrated\",\n      \"pmids\": [\"15685234\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"PRSS21 and related serine proteases (tryptase 5/Prss32, pancreasin/Prss27, testis serine protease-1) are inserted into plasma membranes via glycosylphosphatidylinositol (GPI) anchors, as demonstrated by phosphatidylinositol-specific phospholipase C release, and are consequently targeted to lipid rafts.\",\n      \"method\": \"PI-PLC treatment, cell surface release assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — PI-PLC release assay directly confirms GPI anchoring; single lab; corroborates earlier PMID:11861648 finding\",\n      \"pmids\": [\"16143303\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Prss21-null epididymal sperm penetrate the zona pellucida (ZP) at very low rates in vitro, due to reduced ability to bind the ZP and undergo ZP-induced acrosome reaction. Sperm-egg fusion in vitro was also severely impaired. Importantly, the reduced fertility of Prss21-null epididymal sperm was rescued by exposure to the uterine microenvironment (in vivo passage through uterus or in vitro treatment with uterine fluids), demonstrating that PRSS21's proteolytic function in ZP penetration can be compensated by uterine factors.\",\n      \"method\": \"Prss21 knockout mouse model, in vitro fertilization assay, ZP binding assay, acrosome reaction assay, uterine fluid treatment experiment\",\n      \"journal\": \"Genes to cells : devoted to molecular & cellular mechanisms\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO mouse model with defined cellular phenotypes; multiple orthogonal functional assays (ZP binding, acrosome reaction, sperm-egg fusion, uterine fluid rescue); single lab but rigorous\",\n      \"pmids\": [\"18754795\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"PRSS21-deficient spermatozoa show decreased motility, angulated and curled tails, fragile necks, and dramatically increased susceptibility to decapitation during epididymal transit. Histological and electron microscopic analyses showed increased curling and detachment of tails as spermatozoa transit from corpus to cauda epididymis. Cauda epididymal spermatozoa deficient in PRSS21 fail to mount a swelling response to hypotonic conditions, indicating impaired osmotic regulatory ability. These defects identify PRSS21 as a novel proteolytic factor directing epididymal sperm maturation and fertilizing ability.\",\n      \"method\": \"PRSS21 knockout mouse model, light and electron microscopy, sperm motility analysis, hypotonic swelling test\",\n      \"journal\": \"Biology of reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO mouse with multiple structural and functional phenotypic readouts; electron microscopy validation; multiple independent assays in one study\",\n      \"pmids\": [\"19571264\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Double-knockout mice lacking both ACR (acrosin) and PRSS21 are subfertile in vivo, and their sperm are unable to undergo acrosomal exocytosis on the zona pellucida surface or traverse the ZP in vitro, and are also defective in penetrating the cumulus matrix. Artificial insemination directly into the uterus partially rescued fertilization, as did the presence of uterine fluids in vitro. This demonstrates that the trypsin-like protease activity of ACR and PRSS21 together is essential for sperm penetration through cumulus matrix and ZP in vitro, while female reproductive tract factors can partially compensate in vivo.\",\n      \"method\": \"Double-knockout mouse generation (ACR and PRSS21), in vitro fertilization assay, acrosome reaction assay on ZP, cumulus penetration assay, artificial insemination experiment\",\n      \"journal\": \"Biology of reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — double-KO epistasis experiment with multiple orthogonal functional assays; directly tests pathway position of PRSS21 relative to ACR in fertilization\",\n      \"pmids\": [\"20484738\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Testisin (PRSS21) surface expression on stallion spermatozoa increases significantly upon capacitation and further increases after acrosome reaction, with localization to the equatorial region of the sperm head. Testisin is also found in epididymal luminal fluid and epithelial cells. Blue Native PAGE and co-immunoprecipitation followed by mass spectrometry revealed that testisin forms several high-molecular-weight multiprotein complexes and interacts with zona pellucida-binding proteins including ZPBP, ZAN, acrosin, multiple heat-shock proteins, and components of the TCP1 complex, indicating participation in the ZP-binding complex.\",\n      \"method\": \"Live cell immunofluorescence, flow cytometry, immunohistochemistry, Blue Native PAGE, co-immunoprecipitation, mass spectrometry\",\n      \"journal\": \"Andrology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP with MS identification of interacting partners; live cell localization with functional context; multiple orthogonal methods in single study\",\n      \"pmids\": [\"30549223\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In a murine xenograft model of ovarian intraperitoneal tumor metastasis, increased tumor testisin expression inhibited intraperitoneal tumor seeding, colonization, ascites accumulation, and metastatic tumor burden in a manner dependent on catalytically active testisin. Testisin activity suppresses the synthesis and secretion of pro-angiogenic angiopoietins ANG2 and ANGPTL4 (which promote vascular leak and edema). Gene profiling and mechanistic studies support a model wherein testisin activates protease-activated receptor-2 (PAR-2) as a substrate to antagonize pro-angiogenic angiopoietins that modulate vascular permeability.\",\n      \"method\": \"Murine xenograft model with testisin-overexpressing ovarian cancer cells, catalytic mutant controls, gene expression profiling, mechanistic studies of ANG2/ANGPTL4 secretion\",\n      \"journal\": \"Journal of molecular medicine (Berlin, Germany)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo model with catalytic-mutant control establishing mechanism dependence; substrate (PAR-2) and downstream effectors (ANG2, ANGPTL4) identified; multiple orthogonal methods\",\n      \"pmids\": [\"30911775\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Testisin (PRSS21)-deficient mice (Prss21-/-) show a substantially increased incidence and severity of hemorrhages during corpus luteal development, associated with increased vascular leakiness (greater Evans blue dye extravasation). siRNA knockdown of testisin in microvascular endothelial cells impaired reorganization and tubule-like formation on Matrigel and increased paracellular permeability to FITC-albumin, associated with decreased VE-cadherin expression and increased phospho(Tyr658)-VE-cadherin levels. Tight junction proteins occludin, claudin-5, and ZO-1 were unaffected. These data identify testisin as a novel regulator of VE-cadherin-mediated endothelial adherens junctions during angiogenesis.\",\n      \"method\": \"Prss21-/- mouse model, Evans blue extravasation assay, siRNA knockdown in endothelial cells, Matrigel tubule formation assay, FITC-albumin permeability assay, Western blot for VE-cadherin and phospho-VE-cadherin, live cell imaging\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO mouse combined with siRNA knockdown and multiple in vitro functional assays; specific molecular mechanism (VE-cadherin phosphorylation) identified; multiple orthogonal methods\",\n      \"pmids\": [\"32511276\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SPEM2 interacts with PRSS21 (testisin) in epididymal sperm and is required for its processing and maturation. Co-immunoprecipitation demonstrated SPEM2 interaction with PRSS21 along with ZPBP, PRSS54, PRSS55, ADAM2, and ADAM3. SPEM2 deficiency in mice resulted in decreased levels of processed/mature PRSS21 in epididymal sperm.\",\n      \"method\": \"Co-immunoprecipitation, Western blot in Spem2 knockout mice\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP identifies SPEM2 as a PRSS21 interaction partner; KO model shows dependency of PRSS21 maturation on SPEM2; single lab, limited mechanistic depth on PRSS21 specifically\",\n      \"pmids\": [\"38421455\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Fluoride exposure in rats downregulated PRSS21 expression (both mRNA and protein) in the epididymis in a dose-dependent manner, which was associated with reduced sperm ability to break down the egg cumulus cell layer. Immunofluorescence confirmed altered localization of PRSS21 protein in fluoride-treated epididymis.\",\n      \"method\": \"In vivo fluoride exposure in rats, Western blot, RT-PCR, immunofluorescence, sperm-egg cumulus penetration assay\",\n      \"journal\": \"Journal of agricultural and food chemistry\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — correlative downregulation of PRSS21 by fluoride with functional phenotype; no direct manipulation of PRSS21 itself; single lab, single model\",\n      \"pmids\": [\"31008594\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PRSS21 (testisin/ESP-1) is a GPI-anchored serine protease with trypsin-like activity that localizes to lipid rafts on the sperm cell surface and in microvascular endothelial cells; in spermatozoa it is required for epididymal maturation, osmotic regulation, ZP binding, acrosome reaction, and cumulus/ZP penetration during fertilization (redundantly with acrosin), forms multiprotein complexes with ZP-binding proteins, and its processing depends on SPEM2; in ovarian cancer and endothelial cells, catalytically active testisin activates PAR-2 to suppress pro-angiogenic ANG2 and ANGPTL4 secretion and maintains VE-cadherin-mediated vascular integrity; loss of PRSS21 expression in testicular germ cell tumors is caused by CpG island hypermethylation and histone deacetylation, and its re-expression suppresses tumor growth.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PRSS21 (testisin/ESP-1) is a GPI-anchored, trypsin-like serine protease that operates in two distinct biological settings: male germ cell maturation and fertilization, and endothelial/vascular regulation [#0, #7, #11]. The mature protein carries a canonical His-Asp-Ser catalytic triad and a C-terminal hydrophobic GPI-anchor extension that targets it to Triton X-100-insoluble lipid raft microdomains of the cell surface [#0, #1]. In spermatozoa, testisin is required for epididymal sperm maturation, maintaining tail integrity and osmotic regulatory capacity during epididymal transit, and for fertilization steps including zona pellucida binding, ZP-induced acrosome reaction, and cumulus/ZP penetration; this proteolytic function acts redundantly with acrosin and can be compensated by uterine factors in vivo [#7, #8, #9]. On the sperm surface it assembles into high-molecular-weight multiprotein complexes with zona pellucida-binding proteins including ZPBP, ZAN, and acrosin, and its processing to the mature form depends on SPEM2 [#10, #13]. In ovarian cancer and microvascular endothelial cells, catalytically active testisin activates the receptor PAR-2 to suppress secretion of pro-angiogenic ANG2 and ANGPTL4 and maintains VE-cadherin-mediated adherens junctions, thereby restraining vascular leak, tumor seeding, and metastasis [#11, #12]. In testicular germ cell tumors, PRSS21 expression is silenced by 5'-CpG island hypermethylation and histone deacetylation, and its re-expression suppresses anchorage-dependent growth and xenograft tumor formation, defining a tumor suppressor activity [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Initial cloning established PRSS21 as a membrane-type serine protease with the molecular hallmarks needed for catalytic activity and membrane attachment, framing it as a candidate protease in testis biology.\",\n      \"evidence\": \"cDNA cloning from human eosinophils with deduced sequence and tissue distribution analysis\",\n      \"pmids\": [\"9826525\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Enzymatic activity not functionally validated\", \"GPI anchoring inferred from sequence, not demonstrated\", \"No cellular function assigned\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Genomic characterization mapped the gene and promoter and first noted that testisin is expressed in premeiotic germ cells but lost in testicular tumor cell lines, hinting at a cancer-relevant expression pattern.\",\n      \"evidence\": \"Genomic library screening, radiation hybrid mapping, and RT-PCR across tumor cell lines\",\n      \"pmids\": [\"11004480\", \"10600542\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of tumor-associated silencing unknown\", \"No functional consequence of expression loss tested\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Murine gene characterization tied PRSS21 expression to the appearance of spermatids during spermatogenesis, localizing it to spermatid cytoplasm and plasma membrane and establishing a temporally regulated germ-cell role.\",\n      \"evidence\": \"Genomic cloning and immunostaining of mouse testis sections across postnatal development\",\n      \"pmids\": [\"11231276\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Function in sperm not tested\", \"GPI anchor not biochemically confirmed at this stage\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Biochemical work confirmed that PRSS21 is GPI-anchored and partitions into sperm lipid rafts, and that its enzymatic specificity is trypsin-like but distinct from acrosin and pancreatic trypsin, resolving its surface topology and catalytic identity.\",\n      \"evidence\": \"Recombinant expression in HEK293 cells with PI-PLC release, Triton X-100 raft fractionation, and substrate specificity assays\",\n      \"pmids\": [\"11861648\", \"16143303\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological substrates not identified\", \"Catalytic role in fertilization not yet demonstrated\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"The cause and consequence of PRSS21 loss in cancer were established: epigenetic silencing via CpG hypermethylation and histone deacetylation, with re-expression suppressing tumor growth, defining a tumor suppressor function.\",\n      \"evidence\": \"Bisulfite sequencing, demethylating/HDAC inhibitor reactivation, stable transfection, and SCID mouse xenografts\",\n      \"pmids\": [\"15685234\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Catalytic dependence of tumor suppression not tested here\", \"Downstream effectors of growth suppression unknown\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Knockout and double-knockout studies defined the cellular role of PRSS21 in fertilization, showing it is required for epididymal sperm structural integrity and osmotic regulation and, redundantly with acrosin, for ZP and cumulus penetration, with uterine factors compensating in vivo.\",\n      \"evidence\": \"Prss21 single- and Acr/Prss21 double-knockout mice with IVF, ZP binding, acrosome reaction, cumulus penetration, hypotonic swelling, and uterine fluid rescue assays\",\n      \"pmids\": [\"18754795\", \"19571264\", \"20484738\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct proteolytic substrates on sperm/egg not identified\", \"Molecular basis of uterine compensation unknown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Proteomic analysis placed testisin within the sperm ZP-binding machinery, showing capacitation/acrosome-dependent surface dynamics and assembly into multiprotein complexes with ZP-binding proteins.\",\n      \"evidence\": \"Live cell immunofluorescence, flow cytometry, Blue Native PAGE, and Co-IP/mass spectrometry on stallion sperm\",\n      \"pmids\": [\"30549223\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct vs indirect nature of interactions not resolved\", \"Functional necessity of complex assembly not tested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"A vascular function was established: testisin maintains endothelial barrier integrity through VE-cadherin, with loss increasing vascular leak and decreasing VE-cadherin while elevating its inhibitory phosphorylation, and a parallel oncology study linked catalytically active testisin to PAR-2-mediated suppression of pro-angiogenic angiopoietins.\",\n      \"evidence\": \"Prss21-/- mice, endothelial siRNA knockdown, Matrigel tubule and FITC-albumin permeability assays, VE-cadherin Western blots; plus xenograft model with catalytic-mutant controls and ANG2/ANGPTL4 profiling\",\n      \"pmids\": [\"32511276\", \"30911775\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct demonstration that testisin cleaves PAR-2 on endothelium incomplete\", \"Connection between PAR-2 activation and VE-cadherin phosphorylation not fully mapped\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"An upstream processing requirement was identified, showing SPEM2 interacts with PRSS21 and is needed for its maturation in epididymal sperm, embedding testisin in a broader sperm protein-processing network.\",\n      \"evidence\": \"Co-immunoprecipitation and Western blot in Spem2 knockout mice\",\n      \"pmids\": [\"38421455\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs indirect SPEM2-PRSS21 interaction unresolved\", \"Protease responsible for PRSS21 processing not identified\", \"Limited mechanistic depth on PRSS21 specifically\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The endogenous physiological substrates of testisin on the sperm surface and the precise enzymatic steps linking its activity to ZP/cumulus penetration and to endothelial barrier maintenance remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct sperm-side proteolytic substrate identified\", \"Mechanism linking PAR-2 cleavage to VE-cadherin stabilization not fully resolved\", \"Structural model of testisin and its complexes absent\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 11]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 7]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 4, 6]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [7, 8, 9]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [5, 11]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [11, 12]}\n    ],\n    \"complexes\": [\n      \"sperm zona pellucida-binding complex\"\n    ],\n    \"partners\": [\n      \"ZPBP\",\n      \"ZAN\",\n      \"ACR\",\n      \"SPEM2\",\n      \"ADAM2\",\n      \"ADAM3\",\n      \"PRSS54\",\n      \"PRSS55\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}