{"gene":"ACRBP","run_date":"2026-04-28T17:12:37","timeline":{"discoveries":[{"year":1994,"finding":"Porcine sp32 (ACRBP) was purified as a binding protein specific for 55-, 53-, and 49-kDa forms of proacrosin and an acrosin intermediate, but not for 43-kDa acrosin intermediate or 35-kDa mature acrosin. sp32 significantly accelerated autoactivation of proacrosin at basic pH in vitro and altered the maturation pathway, causing accumulation of the 49-kDa intermediate. sp32 is produced by post-translational processing of a 61-kDa precursor protein.","method":"Protein purification, SDS-PAGE, in vitro binding assay, in vitro proacrosin autoactivation assay, cDNA cloning and sequence analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — reconstituted in vitro binding and enzymatic activity, foundational paper with >100 citations","pmids":["8144514"],"is_preprint":false},{"year":2005,"finding":"sp32 (ACRBP) is tyrosine phosphorylated during capacitation of pig sperm. The tyrosine-phosphorylated form (p32) appears specifically under capacitating conditions and co-localizes with anti-phosphotyrosine labeling at the acrosome; this labeling disappears after the acrosome reaction.","method":"2D Western blotting under non-reducing/reducing conditions, mass spectrometry/MS identification, immunoprecipitation with anti-phosphotyrosine and anti-sp32 antibodies, indirect immunofluorescence","journal":"Journal of andrology","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (MS identification, reciprocal IP, immunofluorescence) in a single study","pmids":["15955892"],"is_preprint":false},{"year":2012,"finding":"ACRBP/sp32 undergoes proteolytic processing from a 58.5 kDa precursor to a 27.5 kDa mature form; this processing is absent in PCSK4-null mice, implicating proprotein convertase 4 (PCSK4) or a PCSK4-dependent enzyme in ACRBP maturation. In PCSK4-null mice, proacrosin fails to undergo autoactivation, supporting a role for mature ACRBP in regulating proacrosin conversion. ACRBP-null processing also correlates with sperm head/acrosome morphological defects.","method":"2D differential in-gel electrophoresis (DIGE), Western blot, immunolocalization in PCSK4 knockout mice","journal":"Molecular human reproduction","confidence":"Medium","confidence_rationale":"Tier 2 — KO mouse model with defined biochemical phenotype, but PCSK4 as direct writer not fully confirmed (may be indirect)","pmids":["22357636"],"is_preprint":false},{"year":2013,"finding":"Two functional forms of mouse ACRBP are generated by alternative splicing: ACRBP-W (wild-type) and ACRBP-V5 (intron 5-retaining). ACRBP-W is processed into mature ACRBP-C by removal of the N-terminal half. GST pull-down assays showed ACRBP-V5 and ACRBP-C bind different domains within the C-terminal region of proacrosin. ACRBP-C markedly accelerates proacrosin autoactivation in vitro. ACRBP-V5 localizes to acrosomal granules of early round spermatids; ACRBP-C is present in sperm acrosome.","method":"Alternative splicing analysis, GST pull-down assay, in vitro proacrosin autoactivation assay, immunolocalization","journal":"Biology of reproduction","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution (pull-down and autoactivation assay) plus localization, multiple orthogonal methods","pmids":["23426433"],"is_preprint":false},{"year":2016,"finding":"ACRBP-null male mice (lacking both ACRBP-W and ACRBP-V5) show severely reduced fertility due to malformation of the acrosome; null spermatids fail to form a large acrosomal granule, producing a fragmented acrosome. Transgenic rescue with ACRBP-V5 alone restores acrosome formation, demonstrating ACRBP-V5 functions in acrosomal granule formation during early spermiogenesis. Exogenously expressed ACRBP-W blocked proacrosin autoactivation in the acrosome, demonstrating ACRBP-W retains proacrosin in an inactive state until acrosomal exocytosis.","method":"Gene knockout mouse, transgenic rescue experiment, in vivo acrosome morphology analysis, fertility assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1–2 — KO + transgenic rescue with specific phenotypic readout, two isoforms functionally dissected","pmids":["27303034"],"is_preprint":false},{"year":2015,"finding":"In boar sperm, expression and tyrosine phosphorylation of sp32 (ACRBP) are upregulated during capacitation and the acrosome reaction. Higher sp32 tyrosine phosphorylation correlates with activation of the proacrosin/acrosin system, supporting a regulatory role for sp32 phosphorylation in proacrosin activation.","method":"SDS-PAGE, Western blot with anti-sp32 and anti-phosphotyrosine antibodies across different sperm treatment conditions (fresh, capacitated, frozen-thawed, post-acrosome reaction)","journal":"Genetics and molecular research","confidence":"Medium","confidence_rationale":"Tier 3 — single lab, correlative Western blot without direct enzymatic readout","pmids":["25867384"],"is_preprint":false},{"year":2021,"finding":"In porcine sperm, anti-ACRBP antibodies reduced capacitation and spontaneous acrosome reaction, and inhibited sperm-zona pellucida (ZP) binding. Surface-localized ACRBP on the sperm head facilitates the acrosome reaction triggered by solubilized ZP or SERCA inhibition, demonstrating ACRBP participates in sperm-ZP binding and acrosome reaction priming.","method":"Antibody inhibition experiments in IVF system, sperm-ZP binding assay, acrosome reaction assay, indirect immunofluorescence localization","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — functional antibody-inhibition assay with defined physiological readouts (capacitation, AR, ZP binding)","pmids":["34086710"],"is_preprint":false},{"year":2018,"finding":"ACRBP-deficient mouse sperm show markedly reduced numbers in the oviduct after mating and a marked reduction in ability to access unfertilized oocytes, despite normal motility and morphology of recovered sperm, indicating subfertility is attributable to defects in the acrosome reaction rather than sperm migration.","method":"ACRBP knockout mouse, sperm counting in female reproductive tract post-mating, motility and morphology analysis","journal":"The Journal of reproduction and development","confidence":"Medium","confidence_rationale":"Tier 2 — KO mouse with defined behavioral phenotype in vivo, pathway placement via elimination","pmids":["30606959"],"is_preprint":false},{"year":2012,"finding":"OY-TES-1 knockdown by RNAi in human bone marrow-derived mesenchymal stem cells caused cell growth inhibition, cell cycle arrest, apoptosis induction, and reduced migration ability.","method":"RNAi knockdown, cell viability assay, cell cycle analysis by flow cytometry, apoptosis assay, migration assay","journal":"Cell biology international","confidence":"Low","confidence_rationale":"Tier 3 — single lab, loss-of-function with phenotype but no molecular pathway placement for ACRBP specifically","pmids":["22651134"],"is_preprint":false},{"year":2015,"finding":"Knockdown of OY-TES-1 (ACRBP) by siRNA in hepatocellular carcinoma cell lines decreased cell growth, induced G0/G1 arrest and apoptosis, and prevented migration and invasion. Mechanistically, knockdown increased caspase-3 expression, decreased cyclin E, MMP2, and MMP9 levels.","method":"siRNA knockdown, cell cycle analysis, apoptosis assay, migration/invasion assay, Western blot for caspase-3, cyclin E, MMP2, MMP9","journal":"International journal of clinical and experimental pathology","confidence":"Low","confidence_rationale":"Tier 3 — single lab, mechanistic markers measured but pathway not directly validated for ACRBP","pmids":["26339343"],"is_preprint":false},{"year":2022,"finding":"ACRBP protein is specifically expressed in sperm cells (not in female blood or epithelial cells) and localizes to the acrosome, as confirmed by Western blotting and immunofluorescence.","method":"Western blot, immunofluorescence localization","journal":"International journal of legal medicine","confidence":"Low","confidence_rationale":"Tier 3 — localization confirmed but no functional consequence tested in this study","pmids":["36418581"],"is_preprint":false}],"current_model":"ACRBP (sp32/OY-TES-1) is an acrosomal matrix protein expressed as two alternatively spliced isoforms (ACRBP-V5 and ACRBP-W/ACRBP-C) that serve distinct functions: ACRBP-V5 is required for proper acrosomal granule formation during early spermiogenesis, while ACRBP-C (the processed mature form of ACRBP-W) binds proacrosin via the C-terminal region to retain it in an inactive state and, upon acrosomal exocytosis, accelerates proacrosin autoactivation; additionally, ACRBP undergoes tyrosine phosphorylation during capacitation and participates in sperm-zona pellucida binding and the acrosome reaction, with its proteolytic maturation from a ~60 kDa precursor dependent on PCSK4-related convertase activity."},"narrative":{"teleology":[{"year":1994,"claim":"Identification of sp32 (ACRBP) as a proacrosin-binding protein that accelerates proacrosin autoactivation established the first molecular function for this acrosomal factor.","evidence":"Protein purification and in vitro binding/autoactivation assays using porcine sperm","pmids":["8144514"],"confidence":"High","gaps":["Mechanism by which sp32 accelerates autoactivation unclear at molecular level","In vivo relevance of proacrosin autoactivation modulation not demonstrated","Post-translational processing from 61 kDa precursor not characterized"]},{"year":2005,"claim":"Discovery that ACRBP is tyrosine-phosphorylated during capacitation linked this acrosomal protein to sperm signaling events that prime fertilization competence.","evidence":"2D Western blot, mass spectrometry, reciprocal immunoprecipitation, and immunofluorescence in porcine sperm","pmids":["15955892"],"confidence":"High","gaps":["Kinase responsible for ACRBP tyrosine phosphorylation not identified","Functional consequence of phosphorylation on proacrosin binding or activation not tested","Whether phosphorylation occurs in species other than pig not shown"]},{"year":2012,"claim":"Demonstrating that PCSK4-null mice fail to process ACRBP from precursor to mature form and fail to activate proacrosin identified the proteolytic maturation pathway required for ACRBP function.","evidence":"2D-DIGE, Western blot, and immunolocalization in PCSK4 knockout mouse sperm","pmids":["22357636"],"confidence":"Medium","gaps":["Whether PCSK4 directly cleaves ACRBP or acts indirectly through another protease is unresolved","Exact cleavage site in ACRBP not mapped","Relationship between processing defect and acrosome morphology defects not mechanistically delineated"]},{"year":2013,"claim":"Identification of two functional isoforms (ACRBP-V5 and ACRBP-C) that bind distinct proacrosin domains and have different subcellular distributions revealed that alternative splicing diversifies ACRBP function across spermiogenesis stages.","evidence":"Alternative splicing analysis, GST pull-down, in vitro proacrosin autoactivation assay, and immunolocalization in mouse spermatids and sperm","pmids":["23426433"],"confidence":"High","gaps":["The functional significance of binding different proacrosin domains not mechanistically explained","Role of ACRBP-V5 in acrosomal granule formation was inferred from localization but not yet proven by loss-of-function"]},{"year":2016,"claim":"Knockout and isoform-specific transgenic rescue proved that ACRBP-V5 is necessary and sufficient for acrosomal granule formation while ACRBP-W retains proacrosin in an inactive state, definitively assigning non-redundant functions to each isoform.","evidence":"ACRBP knockout mouse with ACRBP-V5 transgenic rescue, acrosome morphology analysis, fertility assay","pmids":["27303034"],"confidence":"High","gaps":["Molecular mechanism by which ACRBP-V5 drives granule coalescence is unknown","Whether ACRBP-W rescue alone can restore fertility not tested","Structural basis for proacrosin retention by ACRBP-W not determined"]},{"year":2018,"claim":"Demonstrating that ACRBP-null sperm reach the oviduct in reduced numbers and fail to access oocytes despite normal motility specified that the subfertility phenotype arises from acrosome reaction defects rather than transport failure.","evidence":"ACRBP knockout mouse with post-mating sperm counting and motility/morphology analysis in the female tract","pmids":["30606959"],"confidence":"Medium","gaps":["Acrosome reaction kinetics not directly measured in vivo","Whether reduced oviductal numbers reflect impaired sperm reservoir binding not excluded"]},{"year":2021,"claim":"Antibody-blocking experiments established that surface-localized ACRBP directly participates in sperm–zona pellucida binding and acrosome reaction priming, extending its function beyond an intracellular proacrosin regulator.","evidence":"Anti-ACRBP antibody inhibition in porcine IVF, sperm-ZP binding assay, acrosome reaction assay","pmids":["34086710"],"confidence":"Medium","gaps":["ZP ligand for ACRBP not identified","Mechanism of ACRBP surface exposure not characterized","Whether ZP-binding role applies across species not tested"]},{"year":null,"claim":"Key unresolved questions include the structural basis of ACRBP–proacrosin interaction, the identity of the kinase mediating capacitation-dependent tyrosine phosphorylation, the mechanism by which ACRBP-V5 drives acrosomal granule coalescence, and whether surface ACRBP directly contacts zona pellucida glycoproteins.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of ACRBP or its complex with proacrosin exists","Tyrosine phosphorylation site(s) and responsible kinase unknown","Mechanism of ACRBP-V5 function in granule biogenesis completely uncharacterized at molecular level"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,3,4]}],"localization":[{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[3,4,10]}],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[4,6,7]}],"complexes":[],"partners":["ACR","PCSK4"],"other_free_text":[]},"mechanistic_narrative":"ACRBP is an acrosomal matrix protein essential for male fertility that functions through two alternatively spliced isoforms with distinct roles in spermiogenesis and fertilization. ACRBP-V5 is required for acrosomal granule formation during early spermiogenesis, as demonstrated by knockout mice that exhibit fragmented acrosomes and severely reduced fertility, with transgenic rescue by ACRBP-V5 alone restoring acrosome biogenesis [PMID:27303034]. The mature processed form, ACRBP-C (derived from ACRBP-W by PCSK4-dependent proteolytic cleavage of a ~60 kDa precursor), binds proacrosin to retain it in an inactive state within the acrosome and, upon acrosomal exocytosis, accelerates proacrosin autoactivation [PMID:8144514, PMID:23426433, PMID:22357636]. ACRBP additionally undergoes tyrosine phosphorylation during capacitation and participates in sperm–zona pellucida binding and acrosome reaction priming [PMID:15955892, PMID:34086710]."},"prefetch_data":{"uniprot":{"accession":"Q8NEB7","full_name":"Acrosin-binding protein","aliases":["Acrosin-binding protein, 60 kDa form","Cancer/testis antigen 23","CT23","Cancer/testis antigen OY-TES-1","Proacrosin-binding protein sp32"],"length_aa":543,"mass_kda":61.4,"function":"Acrosomal protein that maintains proacrosin (pro-ACR) as an enzymatically inactive zymogen in the acrosome. Involved also in the acrosome formation","subcellular_location":"Secreted; Cytoplasmic vesicle, secretory vesicle, acrosome","url":"https://www.uniprot.org/uniprotkb/Q8NEB7/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ACRBP","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/ACRBP","total_profiled":1310},"omim":[{"mim_id":"608352","title":"ACROSIN-BINDING PROTEIN; ACRBP","url":"https://www.omim.org/entry/608352"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Vesicles","reliability":"Approved"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"testis","ntpm":271.0}],"url":"https://www.proteinatlas.org/search/ACRBP"},"hgnc":{"alias_symbol":["SP32","OY-TES-1","CT23"],"prev_symbol":[]},"alphafold":{"accession":"Q8NEB7","domains":[{"cath_id":"-","chopping":"39-120","consensus_level":"high","plddt":89.697,"start":39,"end":120},{"cath_id":"-","chopping":"319-413","consensus_level":"medium","plddt":79.0998,"start":319,"end":413},{"cath_id":"-","chopping":"426-537","consensus_level":"high","plddt":83.0729,"start":426,"end":537}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8NEB7","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8NEB7-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8NEB7-F1-predicted_aligned_error_v6.png","plddt_mean":63.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ACRBP","jax_strain_url":"https://www.jax.org/strain/search?query=ACRBP"},"sequence":{"accession":"Q8NEB7","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8NEB7.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8NEB7/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8NEB7"}},"corpus_meta":[{"pmid":"8144514","id":"PMC_8144514","title":"An acrosomal protein, sp32, in mammalian sperm is a binding protein specific for two proacrosins and an acrosin intermediate.","date":"1994","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/8144514","citation_count":115,"is_preprint":false},{"pmid":"11248070","id":"PMC_11248070","title":"Identification of proacrosin binding protein sp32 precursor as a human cancer/testis antigen.","date":"2001","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/11248070","citation_count":93,"is_preprint":false},{"pmid":"23768753","id":"PMC_23768753","title":"Acrosin-binding protein (ACRBP) and triosephosphate isomerase (TPI) are good markers to predict boar sperm freezing capacity.","date":"2013","source":"Theriogenology","url":"https://pubmed.ncbi.nlm.nih.gov/23768753","citation_count":74,"is_preprint":false},{"pmid":"15955892","id":"PMC_15955892","title":"The proacrosin binding protein, sp32, is tyrosine phosphorylated during capacitation of pig sperm.","date":"2005","source":"Journal of andrology","url":"https://pubmed.ncbi.nlm.nih.gov/15955892","citation_count":60,"is_preprint":false},{"pmid":"24457462","id":"PMC_24457462","title":"Expression of cancer-testis antigens MAGEA1, MAGEA3, ACRBP, PRAME, SSX2, and CTAG2 in myxoid and round cell liposarcoma.","date":"2014","source":"Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc","url":"https://pubmed.ncbi.nlm.nih.gov/24457462","citation_count":59,"is_preprint":false},{"pmid":"31499268","id":"PMC_31499268","title":"Production, purification, and in vivo evaluation of a novel multiepitope peptide vaccine consisted of immunodominant epitopes of SYCP1 and ACRBP antigens as a prophylactic melanoma vaccine.","date":"2019","source":"International immunopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/31499268","citation_count":56,"is_preprint":false},{"pmid":"27303034","id":"PMC_27303034","title":"Biogenesis of sperm acrosome is regulated by pre-mRNA alternative splicing of Acrbp in the mouse.","date":"2016","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/27303034","citation_count":47,"is_preprint":false},{"pmid":"23209854","id":"PMC_23209854","title":"Salivary antigen SP32 is the immunodominant target of the antibody response to Phlebotomus papatasi bites in humans.","date":"2012","source":"PLoS neglected tropical diseases","url":"https://pubmed.ncbi.nlm.nih.gov/23209854","citation_count":44,"is_preprint":false},{"pmid":"10080701","id":"PMC_10080701","title":"Regulation of biosynthesis and cellular localization of Sp32 annexins in tobacco BY2 cells.","date":"1999","source":"Plant molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/10080701","citation_count":34,"is_preprint":false},{"pmid":"16964386","id":"PMC_16964386","title":"OY-TES-1 expression and serum immunoreactivity in epithelial ovarian cancer.","date":"2006","source":"International journal of oncology","url":"https://pubmed.ncbi.nlm.nih.gov/16964386","citation_count":34,"is_preprint":false},{"pmid":"22357636","id":"PMC_22357636","title":"Alteration in the processing of the ACRBP/sp32 protein and sperm head/acrosome malformations in proprotein convertase 4 (PCSK4) null mice.","date":"2012","source":"Molecular human reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/22357636","citation_count":33,"is_preprint":false},{"pmid":"32497486","id":"PMC_32497486","title":"Efficacy of co-immunization with the DNA and peptide vaccines containing SYCP1 and ACRBP epitopes in a murine triple-negative breast cancer model.","date":"2020","source":"Human vaccines & immunotherapeutics","url":"https://pubmed.ncbi.nlm.nih.gov/32497486","citation_count":32,"is_preprint":false},{"pmid":"23426433","id":"PMC_23426433","title":"Two functional forms of ACRBP/sp32 are produced by pre-mRNA alternative splicing in the mouse.","date":"2013","source":"Biology of reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/23426433","citation_count":27,"is_preprint":false},{"pmid":"27153822","id":"PMC_27153822","title":"Purification, Chemical Characterization, and Bioactivity of an Extracellular Polysaccharide Produced by the Marine Sponge Endogenous Fungus Alternaria sp. SP-32.","date":"2016","source":"Marine biotechnology (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/27153822","citation_count":26,"is_preprint":false},{"pmid":"34086710","id":"PMC_34086710","title":"ACRBP (Sp32) is involved in priming sperm for the acrosome reaction and the binding of sperm to the zona pellucida in a porcine model.","date":"2021","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/34086710","citation_count":22,"is_preprint":false},{"pmid":"24294369","id":"PMC_24294369","title":"Cancer testis antigen OY-TES-1 expression and serum immunogenicity in colorectal cancer: its relationship to clinicopathological parameters.","date":"2013","source":"International journal of clinical and experimental pathology","url":"https://pubmed.ncbi.nlm.nih.gov/24294369","citation_count":21,"is_preprint":false},{"pmid":"16301813","id":"PMC_16301813","title":"Identification of an HLA-A24-restricted OY-TES-1 epitope recognized by cytotoxic T-cells.","date":"2005","source":"Microbiology and immunology","url":"https://pubmed.ncbi.nlm.nih.gov/16301813","citation_count":17,"is_preprint":false},{"pmid":"22651134","id":"PMC_22651134","title":"Knockdown of OY-TES-1 by RNAi causes cell cycle arrest and migration decrease in bone marrow-derived mesenchymal stem cells.","date":"2012","source":"Cell biology international","url":"https://pubmed.ncbi.nlm.nih.gov/22651134","citation_count":16,"is_preprint":false},{"pmid":"26339343","id":"PMC_26339343","title":"Down-regulation of cancer/testis antigen OY-TES-1 attenuates malignant behaviors of hepatocellular carcinoma cells in vitro.","date":"2015","source":"International journal of clinical and experimental pathology","url":"https://pubmed.ncbi.nlm.nih.gov/26339343","citation_count":15,"is_preprint":false},{"pmid":"28529561","id":"PMC_28529561","title":"Serum immunoreactivity of cancer/testis antigen OY-TES-1 and its tissues expression in glioma.","date":"2017","source":"Oncology letters","url":"https://pubmed.ncbi.nlm.nih.gov/28529561","citation_count":14,"is_preprint":false},{"pmid":"26597026","id":"PMC_26597026","title":"Acrosin-binding protein (ACRBP) in the testes of stallions.","date":"2015","source":"Animal reproduction science","url":"https://pubmed.ncbi.nlm.nih.gov/26597026","citation_count":12,"is_preprint":false},{"pmid":"32044229","id":"PMC_32044229","title":"CT2-3, a novel magnolol analogue suppresses NSCLC cells through triggering cell cycle arrest and apoptosis.","date":"2020","source":"Bioorganic & medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/32044229","citation_count":12,"is_preprint":false},{"pmid":"29224831","id":"PMC_29224831","title":"Reconstruction of oral cavity defect using versatile buccinator myomucosal flaps in the treatment of cT2-3, N0 oral cavity squamous cell carcinoma: Feasibility, morbidity, and functional/oncological outcomes.","date":"2017","source":"Oral oncology","url":"https://pubmed.ncbi.nlm.nih.gov/29224831","citation_count":10,"is_preprint":false},{"pmid":"34377237","id":"PMC_34377237","title":"Combined treatment with epigenetic agents enhances anti-tumor activity of T cells by upregulating the ACRBP expression in hepatocellular carcinoma.","date":"2021","source":"American journal of translational research","url":"https://pubmed.ncbi.nlm.nih.gov/34377237","citation_count":9,"is_preprint":false},{"pmid":"37406849","id":"PMC_37406849","title":"CT2-3 induces cell cycle arrest and apoptosis in rheumatoid arthritis fibroblast-like synoviocytes through regulating PI3K/AKT pathway.","date":"2023","source":"European journal of pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/37406849","citation_count":9,"is_preprint":false},{"pmid":"32862383","id":"PMC_32862383","title":"Cancer-testis Antigen OY-TES-1 Expression and Immunogenicity in Hepatocellular Carcinoma.","date":"2020","source":"Current medical science","url":"https://pubmed.ncbi.nlm.nih.gov/32862383","citation_count":9,"is_preprint":false},{"pmid":"25867384","id":"PMC_25867384","title":"Expression and tyrosine phosphorylation of sp32 regulate the activation of the boar proacrosin/acrosin system.","date":"2015","source":"Genetics and molecular research : GMR","url":"https://pubmed.ncbi.nlm.nih.gov/25867384","citation_count":7,"is_preprint":false},{"pmid":"24391004","id":"PMC_24391004","title":"Activation of proacrosin accompanies upregulation of sp32 protein tyrosine phosphorylation in pig sperm.","date":"2013","source":"Genetics and molecular research : GMR","url":"https://pubmed.ncbi.nlm.nih.gov/24391004","citation_count":6,"is_preprint":false},{"pmid":"38100550","id":"PMC_38100550","title":"Prediction and identification of HLA-A*0201-restricted epitopes from cancer testis antigen CT23.","date":"2023","source":"Human vaccines & immunotherapeutics","url":"https://pubmed.ncbi.nlm.nih.gov/38100550","citation_count":4,"is_preprint":false},{"pmid":"30606959","id":"PMC_30606959","title":"Behavior of ACRBP-deficient mouse sperm in the female reproductive tract.","date":"2018","source":"The Journal of reproduction and development","url":"https://pubmed.ncbi.nlm.nih.gov/30606959","citation_count":4,"is_preprint":false},{"pmid":"33559934","id":"PMC_33559934","title":"CT23 knockdown attenuating malignant behaviors of hepatocellular carcinoma cell is associated with upregulation of metallothionein 1.","date":"2021","source":"Cell biology international","url":"https://pubmed.ncbi.nlm.nih.gov/33559934","citation_count":3,"is_preprint":false},{"pmid":"36418581","id":"PMC_36418581","title":"Magnetic bead-based separation of sperm cells from semen-vaginal fluid mixed stains using an anti-ACRBP antibody.","date":"2022","source":"International journal of legal medicine","url":"https://pubmed.ncbi.nlm.nih.gov/36418581","citation_count":3,"is_preprint":false},{"pmid":"38090303","id":"PMC_38090303","title":"Collaborative multidisciplinary management and expertise of cT2-3 locally advanced operable esophageal squamous cell carcinoma: a report of two cases.","date":"2023","source":"Journal of thoracic disease","url":"https://pubmed.ncbi.nlm.nih.gov/38090303","citation_count":2,"is_preprint":false},{"pmid":"35463688","id":"PMC_35463688","title":"Immunohistochemistry Study of OY-TES-1 Location in Fetal and Adult Human Tissues.","date":"2022","source":"Journal of healthcare engineering","url":"https://pubmed.ncbi.nlm.nih.gov/35463688","citation_count":1,"is_preprint":false},{"pmid":"21968305","id":"PMC_21968305","title":"[Construction of eukaryotic expression vector encoding ACRBP and its expression in hepatocarcinoma cells].","date":"2011","source":"Xi bao yu fen zi mian yi xue za zhi = Chinese journal of cellular and molecular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/21968305","citation_count":1,"is_preprint":false},{"pmid":"41099151","id":"PMC_41099151","title":"Cancer-testis antigen ACRBP: Cytotoxic response to its HLA-A2 restricted peptide and immune features in ovarian cancer.","date":"2025","source":"Human vaccines & immunotherapeutics","url":"https://pubmed.ncbi.nlm.nih.gov/41099151","citation_count":0,"is_preprint":false},{"pmid":"41428155","id":"PMC_41428155","title":"OY-TES-1 Splice Variant V5a in Glioma: A Driver of Malignancy and Potential Therapeutic Target.","date":"2025","source":"Current medical science","url":"https://pubmed.ncbi.nlm.nih.gov/41428155","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.08.15.608142","title":"Morpho-physiological and transcriptomic responses of field pennycress to waterlogging","date":"2024-08-16","source":"bioRxiv","url":"https://doi.org/10.1101/2024.08.15.608142","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":21131,"output_tokens":2895,"usd":0.053409},"stage2":{"model":"claude-opus-4-6","input_tokens":6222,"output_tokens":2033,"usd":0.122902},"total_usd":0.176311,"stage1_batch_id":"msgbatch_01TqNM6p6FsoMBT2jzQTwKBr","stage2_batch_id":"msgbatch_01Ya473eco8sTHbvRymQaU8o","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1994,\n      \"finding\": \"Porcine sp32 (ACRBP) was purified as a binding protein specific for 55-, 53-, and 49-kDa forms of proacrosin and an acrosin intermediate, but not for 43-kDa acrosin intermediate or 35-kDa mature acrosin. sp32 significantly accelerated autoactivation of proacrosin at basic pH in vitro and altered the maturation pathway, causing accumulation of the 49-kDa intermediate. sp32 is produced by post-translational processing of a 61-kDa precursor protein.\",\n      \"method\": \"Protein purification, SDS-PAGE, in vitro binding assay, in vitro proacrosin autoactivation assay, cDNA cloning and sequence analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro binding and enzymatic activity, foundational paper with >100 citations\",\n      \"pmids\": [\"8144514\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"sp32 (ACRBP) is tyrosine phosphorylated during capacitation of pig sperm. The tyrosine-phosphorylated form (p32) appears specifically under capacitating conditions and co-localizes with anti-phosphotyrosine labeling at the acrosome; this labeling disappears after the acrosome reaction.\",\n      \"method\": \"2D Western blotting under non-reducing/reducing conditions, mass spectrometry/MS identification, immunoprecipitation with anti-phosphotyrosine and anti-sp32 antibodies, indirect immunofluorescence\",\n      \"journal\": \"Journal of andrology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (MS identification, reciprocal IP, immunofluorescence) in a single study\",\n      \"pmids\": [\"15955892\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"ACRBP/sp32 undergoes proteolytic processing from a 58.5 kDa precursor to a 27.5 kDa mature form; this processing is absent in PCSK4-null mice, implicating proprotein convertase 4 (PCSK4) or a PCSK4-dependent enzyme in ACRBP maturation. In PCSK4-null mice, proacrosin fails to undergo autoactivation, supporting a role for mature ACRBP in regulating proacrosin conversion. ACRBP-null processing also correlates with sperm head/acrosome morphological defects.\",\n      \"method\": \"2D differential in-gel electrophoresis (DIGE), Western blot, immunolocalization in PCSK4 knockout mice\",\n      \"journal\": \"Molecular human reproduction\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO mouse model with defined biochemical phenotype, but PCSK4 as direct writer not fully confirmed (may be indirect)\",\n      \"pmids\": [\"22357636\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Two functional forms of mouse ACRBP are generated by alternative splicing: ACRBP-W (wild-type) and ACRBP-V5 (intron 5-retaining). ACRBP-W is processed into mature ACRBP-C by removal of the N-terminal half. GST pull-down assays showed ACRBP-V5 and ACRBP-C bind different domains within the C-terminal region of proacrosin. ACRBP-C markedly accelerates proacrosin autoactivation in vitro. ACRBP-V5 localizes to acrosomal granules of early round spermatids; ACRBP-C is present in sperm acrosome.\",\n      \"method\": \"Alternative splicing analysis, GST pull-down assay, in vitro proacrosin autoactivation assay, immunolocalization\",\n      \"journal\": \"Biology of reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution (pull-down and autoactivation assay) plus localization, multiple orthogonal methods\",\n      \"pmids\": [\"23426433\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"ACRBP-null male mice (lacking both ACRBP-W and ACRBP-V5) show severely reduced fertility due to malformation of the acrosome; null spermatids fail to form a large acrosomal granule, producing a fragmented acrosome. Transgenic rescue with ACRBP-V5 alone restores acrosome formation, demonstrating ACRBP-V5 functions in acrosomal granule formation during early spermiogenesis. Exogenously expressed ACRBP-W blocked proacrosin autoactivation in the acrosome, demonstrating ACRBP-W retains proacrosin in an inactive state until acrosomal exocytosis.\",\n      \"method\": \"Gene knockout mouse, transgenic rescue experiment, in vivo acrosome morphology analysis, fertility assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — KO + transgenic rescue with specific phenotypic readout, two isoforms functionally dissected\",\n      \"pmids\": [\"27303034\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"In boar sperm, expression and tyrosine phosphorylation of sp32 (ACRBP) are upregulated during capacitation and the acrosome reaction. Higher sp32 tyrosine phosphorylation correlates with activation of the proacrosin/acrosin system, supporting a regulatory role for sp32 phosphorylation in proacrosin activation.\",\n      \"method\": \"SDS-PAGE, Western blot with anti-sp32 and anti-phosphotyrosine antibodies across different sperm treatment conditions (fresh, capacitated, frozen-thawed, post-acrosome reaction)\",\n      \"journal\": \"Genetics and molecular research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single lab, correlative Western blot without direct enzymatic readout\",\n      \"pmids\": [\"25867384\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In porcine sperm, anti-ACRBP antibodies reduced capacitation and spontaneous acrosome reaction, and inhibited sperm-zona pellucida (ZP) binding. Surface-localized ACRBP on the sperm head facilitates the acrosome reaction triggered by solubilized ZP or SERCA inhibition, demonstrating ACRBP participates in sperm-ZP binding and acrosome reaction priming.\",\n      \"method\": \"Antibody inhibition experiments in IVF system, sperm-ZP binding assay, acrosome reaction assay, indirect immunofluorescence localization\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional antibody-inhibition assay with defined physiological readouts (capacitation, AR, ZP binding)\",\n      \"pmids\": [\"34086710\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"ACRBP-deficient mouse sperm show markedly reduced numbers in the oviduct after mating and a marked reduction in ability to access unfertilized oocytes, despite normal motility and morphology of recovered sperm, indicating subfertility is attributable to defects in the acrosome reaction rather than sperm migration.\",\n      \"method\": \"ACRBP knockout mouse, sperm counting in female reproductive tract post-mating, motility and morphology analysis\",\n      \"journal\": \"The Journal of reproduction and development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO mouse with defined behavioral phenotype in vivo, pathway placement via elimination\",\n      \"pmids\": [\"30606959\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"OY-TES-1 knockdown by RNAi in human bone marrow-derived mesenchymal stem cells caused cell growth inhibition, cell cycle arrest, apoptosis induction, and reduced migration ability.\",\n      \"method\": \"RNAi knockdown, cell viability assay, cell cycle analysis by flow cytometry, apoptosis assay, migration assay\",\n      \"journal\": \"Cell biology international\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single lab, loss-of-function with phenotype but no molecular pathway placement for ACRBP specifically\",\n      \"pmids\": [\"22651134\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Knockdown of OY-TES-1 (ACRBP) by siRNA in hepatocellular carcinoma cell lines decreased cell growth, induced G0/G1 arrest and apoptosis, and prevented migration and invasion. Mechanistically, knockdown increased caspase-3 expression, decreased cyclin E, MMP2, and MMP9 levels.\",\n      \"method\": \"siRNA knockdown, cell cycle analysis, apoptosis assay, migration/invasion assay, Western blot for caspase-3, cyclin E, MMP2, MMP9\",\n      \"journal\": \"International journal of clinical and experimental pathology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single lab, mechanistic markers measured but pathway not directly validated for ACRBP\",\n      \"pmids\": [\"26339343\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ACRBP protein is specifically expressed in sperm cells (not in female blood or epithelial cells) and localizes to the acrosome, as confirmed by Western blotting and immunofluorescence.\",\n      \"method\": \"Western blot, immunofluorescence localization\",\n      \"journal\": \"International journal of legal medicine\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — localization confirmed but no functional consequence tested in this study\",\n      \"pmids\": [\"36418581\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ACRBP (sp32/OY-TES-1) is an acrosomal matrix protein expressed as two alternatively spliced isoforms (ACRBP-V5 and ACRBP-W/ACRBP-C) that serve distinct functions: ACRBP-V5 is required for proper acrosomal granule formation during early spermiogenesis, while ACRBP-C (the processed mature form of ACRBP-W) binds proacrosin via the C-terminal region to retain it in an inactive state and, upon acrosomal exocytosis, accelerates proacrosin autoactivation; additionally, ACRBP undergoes tyrosine phosphorylation during capacitation and participates in sperm-zona pellucida binding and the acrosome reaction, with its proteolytic maturation from a ~60 kDa precursor dependent on PCSK4-related convertase activity.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"ACRBP is an acrosomal matrix protein essential for male fertility that functions through two alternatively spliced isoforms with distinct roles in spermiogenesis and fertilization. ACRBP-V5 is required for acrosomal granule formation during early spermiogenesis, as demonstrated by knockout mice that exhibit fragmented acrosomes and severely reduced fertility, with transgenic rescue by ACRBP-V5 alone restoring acrosome biogenesis [PMID:27303034]. The mature processed form, ACRBP-C (derived from ACRBP-W by PCSK4-dependent proteolytic cleavage of a ~60 kDa precursor), binds proacrosin to retain it in an inactive state within the acrosome and, upon acrosomal exocytosis, accelerates proacrosin autoactivation [PMID:8144514, PMID:23426433, PMID:22357636]. ACRBP additionally undergoes tyrosine phosphorylation during capacitation and participates in sperm–zona pellucida binding and acrosome reaction priming [PMID:15955892, PMID:34086710].\",\n  \"teleology\": [\n    {\n      \"year\": 1994,\n      \"claim\": \"Identification of sp32 (ACRBP) as a proacrosin-binding protein that accelerates proacrosin autoactivation established the first molecular function for this acrosomal factor.\",\n      \"evidence\": \"Protein purification and in vitro binding/autoactivation assays using porcine sperm\",\n      \"pmids\": [\"8144514\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mechanism by which sp32 accelerates autoactivation unclear at molecular level\",\n        \"In vivo relevance of proacrosin autoactivation modulation not demonstrated\",\n        \"Post-translational processing from 61 kDa precursor not characterized\"\n      ]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Discovery that ACRBP is tyrosine-phosphorylated during capacitation linked this acrosomal protein to sperm signaling events that prime fertilization competence.\",\n      \"evidence\": \"2D Western blot, mass spectrometry, reciprocal immunoprecipitation, and immunofluorescence in porcine sperm\",\n      \"pmids\": [\"15955892\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Kinase responsible for ACRBP tyrosine phosphorylation not identified\",\n        \"Functional consequence of phosphorylation on proacrosin binding or activation not tested\",\n        \"Whether phosphorylation occurs in species other than pig not shown\"\n      ]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Demonstrating that PCSK4-null mice fail to process ACRBP from precursor to mature form and fail to activate proacrosin identified the proteolytic maturation pathway required for ACRBP function.\",\n      \"evidence\": \"2D-DIGE, Western blot, and immunolocalization in PCSK4 knockout mouse sperm\",\n      \"pmids\": [\"22357636\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether PCSK4 directly cleaves ACRBP or acts indirectly through another protease is unresolved\",\n        \"Exact cleavage site in ACRBP not mapped\",\n        \"Relationship between processing defect and acrosome morphology defects not mechanistically delineated\"\n      ]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identification of two functional isoforms (ACRBP-V5 and ACRBP-C) that bind distinct proacrosin domains and have different subcellular distributions revealed that alternative splicing diversifies ACRBP function across spermiogenesis stages.\",\n      \"evidence\": \"Alternative splicing analysis, GST pull-down, in vitro proacrosin autoactivation assay, and immunolocalization in mouse spermatids and sperm\",\n      \"pmids\": [\"23426433\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The functional significance of binding different proacrosin domains not mechanistically explained\",\n        \"Role of ACRBP-V5 in acrosomal granule formation was inferred from localization but not yet proven by loss-of-function\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Knockout and isoform-specific transgenic rescue proved that ACRBP-V5 is necessary and sufficient for acrosomal granule formation while ACRBP-W retains proacrosin in an inactive state, definitively assigning non-redundant functions to each isoform.\",\n      \"evidence\": \"ACRBP knockout mouse with ACRBP-V5 transgenic rescue, acrosome morphology analysis, fertility assay\",\n      \"pmids\": [\"27303034\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Molecular mechanism by which ACRBP-V5 drives granule coalescence is unknown\",\n        \"Whether ACRBP-W rescue alone can restore fertility not tested\",\n        \"Structural basis for proacrosin retention by ACRBP-W not determined\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Demonstrating that ACRBP-null sperm reach the oviduct in reduced numbers and fail to access oocytes despite normal motility specified that the subfertility phenotype arises from acrosome reaction defects rather than transport failure.\",\n      \"evidence\": \"ACRBP knockout mouse with post-mating sperm counting and motility/morphology analysis in the female tract\",\n      \"pmids\": [\"30606959\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Acrosome reaction kinetics not directly measured in vivo\",\n        \"Whether reduced oviductal numbers reflect impaired sperm reservoir binding not excluded\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Antibody-blocking experiments established that surface-localized ACRBP directly participates in sperm–zona pellucida binding and acrosome reaction priming, extending its function beyond an intracellular proacrosin regulator.\",\n      \"evidence\": \"Anti-ACRBP antibody inhibition in porcine IVF, sperm-ZP binding assay, acrosome reaction assay\",\n      \"pmids\": [\"34086710\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"ZP ligand for ACRBP not identified\",\n        \"Mechanism of ACRBP surface exposure not characterized\",\n        \"Whether ZP-binding role applies across species not tested\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural basis of ACRBP–proacrosin interaction, the identity of the kinase mediating capacitation-dependent tyrosine phosphorylation, the mechanism by which ACRBP-V5 drives acrosomal granule coalescence, and whether surface ACRBP directly contacts zona pellucida glycoproteins.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No structural model of ACRBP or its complex with proacrosin exists\",\n        \"Tyrosine phosphorylation site(s) and responsible kinase unknown\",\n        \"Mechanism of ACRBP-V5 function in granule biogenesis completely uncharacterized at molecular level\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 3, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [3, 4, 10]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [4, 6, 7]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"ACR\",\n      \"PCSK4\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}