{"gene":"AKAP3","run_date":"2026-06-09T22:02:43","timeline":{"discoveries":[{"year":1999,"finding":"AKAP3 (AKAP110) is a sperm-specific A-kinase anchoring protein whose RII-binding domain was mapped using truncated mutants; the domain forms an amphipathic helix with eight conserved positions responsible for RII interaction. AKAP3 localizes to the acrosomal region of the sperm head and along the entire principal piece, co-compartmentalizing with both RI and RII regulatory subunits of PKA.","method":"Truncated mutant binding assays, immunocytochemistry, Northern blot, in situ hybridization","journal":"Molecular Endocrinology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — RII-binding domain mapped by mutagenesis, localization confirmed by immunocytochemistry, replicated across mouse/bovine/human","pmids":["10319321"],"is_preprint":false},{"year":1999,"finding":"AKAP3 (FSP95/SOB1) is localized to the ribs of the fibrous sheath in the principal piece of the human sperm tail, as determined by indirect immunofluorescence and immunoelectron microscopy. AKAP3 undergoes tyrosine phosphorylation during capacitation of human spermatozoa.","method":"Immunoelectron microscopy, indirect immunofluorescence, Western blot","journal":"Biology of Reproduction","confidence":"High","confidence_rationale":"Tier 2 / Strong — subcellular localization established by immunoelectron microscopy with functional context (capacitation), replicated by independent lab","pmids":["10529264"],"is_preprint":false},{"year":2001,"finding":"Activated Gα13 (heterotrimeric G protein α subunit) directly interacts with AKAP3 (AKAP110), forming a complex with both the regulatory (rPKA) and catalytic (cPKA) subunits of PKA. Gα13 binding to AKAP3 releases the catalytic subunit of PKA from the AKAP3-rPKA complex, resulting in cAMP-independent PKA activation; AKAP110 potentiates this Gα13-induced PKA activation.","method":"Yeast two-hybrid screening, in vitro binding assay, co-immunoprecipitation, PKA activity assay","journal":"Current Biology","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — yeast two-hybrid discovery confirmed by in vitro binding and co-IP, functional consequence (PKA activation) measured in same study","pmids":["11696326"],"is_preprint":false},{"year":2004,"finding":"Bicarbonate stimulates tyrosine phosphorylation of AKAP3 in human spermatozoa through activation of soluble adenylate cyclase (sAC), leading to increased cAMP production and enhanced recruitment of PKA to AKAP3, and this signaling cascade increases sperm motility and hyperactivation.","method":"Western blot, pharmacological inhibition (sAC inhibitor 2OH-estradiol, DIDS, LY294002), sperm motility analysis","journal":"Biology of Reproduction","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacological dissection with multiple inhibitors in single lab, no mutagenesis or reconstitution","pmids":["15342355"],"is_preprint":false},{"year":2005,"finding":"AKAP3 selectively binds PDE4A5 (but not PDE4D) isoform in bovine spermatozoa, as demonstrated by co-immunoprecipitation in COS cells co-transfected with AKAP3 and PDE isoforms, and confirmed by pulldown from sperm lysates. AKAP3 functions as a scaffolding protein that co-localizes with PDE4A in the principal piece to regulate local cAMP concentrations.","method":"Co-immunoprecipitation (COS cell co-transfection), pulldown assay from sperm lysates, immunolocalization","journal":"Biology of Reproduction","confidence":"High","confidence_rationale":"Tier 2 / Moderate — interaction confirmed by two orthogonal methods (COS cell co-IP and sperm lysate pulldown), isoform selectivity tested in same study","pmids":["16177223"],"is_preprint":false},{"year":2011,"finding":"AKAP3 forms a complex with CABYR (calcium-binding tyrosine phosphorylation-regulated protein) and Ropporin in the human sperm fibrous sheath. CABYR binds AKAP3 via its RII-like domain, as confirmed by co-immunoprecipitation and yeast two-hybrid assays.","method":"Co-immunoprecipitation, mass spectrometry, Western blot, yeast two-hybrid","journal":"Asian Journal of Andrology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP confirmed by yeast two-hybrid, two orthogonal methods in single study","pmids":["21240291"],"is_preprint":false},{"year":2013,"finding":"AKAP3 is degraded via the proteasomal machinery during bovine sperm capacitation (inhibited by MG-132). Binding of PKARII to AKAP3 protects AKAP3 from degradation; disruption of PKARII anchoring (with Ht31 peptide) or inhibition/activation of PKA both increase AKAP3 degradation rate. Intracellular alkalization (NH4Cl) also enhances AKAP3 degradation.","method":"Western blot, proteasome inhibitor (MG-132), Ht31 peptide disruption, PKA activity modulators (H89, 8Br-cAMP), calcium chelation","journal":"PLoS ONE","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple pharmacological interventions in single lab, mechanism inferred from inhibitor studies without direct reconstitution","pmids":["23894359"],"is_preprint":false},{"year":2014,"finding":"AKAP3 synthesis during mouse spermiogenesis is regulated by PKA signaling and RNA-binding proteins (RBPs) PIWIL1, PABPC1, and NONO. Nascent AKAP3 forms a protein complex with PKA and these RBPs, which co-localize at the chromatoid body. Activation of PKA positively regulates AKAP3 protein synthesis without changing mRNA levels in elongating spermatids.","method":"Co-immunoprecipitation, protein mass spectrometry, RNA EMSA, sucrose gradient sedimentation, immunofluorescence, PKA activator treatment","journal":"Biology of Reproduction","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP/MS identification of complex confirmed by functional PKA activation experiment, single lab","pmids":["24648398"],"is_preprint":false},{"year":2014,"finding":"AKAP3 is a dual-specificity anchoring protein that interacts with both RIα and RIIα regulatory subunits of PKA via two conserved N-terminal amphipathic peptide domains (named 'dual' and 'RI' domains). In elongating spermatids AKAP3 interacts preferentially with RIα, while in mature sperm it co-localizes exclusively with RIIα in the principal piece.","method":"Mutagenesis of amphipathic domains, in vivo and in vitro binding assays, immunofluorescence, co-immunoprecipitation","journal":"Molecular Reproduction and Development","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — domain mutagenesis combined with in vitro binding and in vivo co-IP, localization confirmed by immunofluorescence","pmids":["24687590"],"is_preprint":false},{"year":2015,"finding":"AKAP3 undergoes tyrosine dephosphorylation during sperm capacitation, and its degradation rate is regulated by its tyrosine phosphorylation status: inhibition of tyrosine phosphatase reduces AKAP3 degradation, while inhibition of tyrosine kinase enhances it. Blocking AKAP3 degradation with anti-AKAP3 antibody in permeabilized cells inhibits the acrosome reaction, demonstrating that AKAP3 degradation is required for capacitation.","method":"Immunoprecipitation, Western blot, tyrosine kinase/phosphatase inhibitors, anti-AKAP3 antibody microinjection into permeabilized cells, FITC-PSA acrosome reaction assay","journal":"Biochimica et Biophysica Acta","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple pharmacological perturbations plus functional antibody blockade, single lab","pmids":["26093290"],"is_preprint":false},{"year":2019,"finding":"Recombinant human oviduct-specific glycoprotein (rHuOVGP1) enhances tyrosine phosphorylation of AKAP3 in the fibrous sheath during capacitation, as shown by co-migration of the pY 105 kDa band with AKAP3 on Western blot and confirmed by immunoprecipitation and co-localization by immunofluorescence.","method":"Western blot, immunoprecipitation, confocal immunofluorescence","journal":"Journal of Assisted Reproduction and Genetics","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP and co-localization confirmed by two orthogonal methods in single lab","pmids":["31254143"],"is_preprint":false},{"year":2020,"finding":"Genetic ablation of AKAP3 in mice causes male sterility due to defects in fibrous sheath formation, loss of sperm motility, and global proteome changes in sperm including mislocalization of PKA subunits and accumulation of RNA metabolism/translation factors. Sperm from both Akap3 and Akap4 null mice accumulate F-actin filaments during post-testicular epididymal maturation.","method":"Mouse knockout (Akap3 null), proteomics, immunofluorescence, electron microscopy, sperm motility analysis","journal":"Development","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO with multiple orthogonal phenotypic readouts including proteomics and structural analysis","pmids":["31969357"],"is_preprint":false},{"year":2022,"finding":"AKAP3 is degraded by the ubiquitin-26S proteasome pathway during sperm capacitation; inhibition of the 26S proteasome with MG132 causes accumulation of ubiquitinated AKAP3 and uncoupling of PKA from AKAP3, leading to PKA degradation by UPP, reduced tyrosine phosphorylation, and increased serine/threonine phosphorylation.","method":"Co-precipitation assays, Western blot, proteasome inhibitor (MG132), flow cytometry","journal":"Animal Reproduction Science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-precipitation and pharmacological inhibition, single lab, consistent with earlier MG132 data","pmids":["36209601"],"is_preprint":false},{"year":2023,"finding":"STK33 kinase directly phosphorylates AKAP3 (and AKAP4); differential phosphoproteomic analysis and in vitro kinase assay identified AKAP3 as a novel phosphorylation substrate of STK33. Loss of STK33 reduces AKAP3 expression in testis and disrupts fibrous sheath assembly in sperm.","method":"Differential phosphoproteomics, in vitro kinase assay, Stk33 knockout/knock-in mice, Western blot, electron microscopy","journal":"Molecular & Cellular Proteomics","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro kinase assay identifies AKAP3 as direct STK33 substrate, confirmed by phosphoproteomics and KO mouse phenotype in single rigorous study","pmids":["37146716"],"is_preprint":false},{"year":2024,"finding":"The dual and RI amphipathic domains in the N-terminus of AKAP3, responsible for binding RIα and RIIα of PKA, are required for sperm hyperactivation and male fertility. Deletion of these domains in mice causes RIα mislocalization from the principal piece to the midpiece of the sperm tail, reduces PKA substrate phosphorylation, and abolishes hyperactivation under capacitation conditions, without altering PKA subunit protein levels. AKAP3 shows a preference for binding RIα over RIIα.","method":"Domain deletion mutant mice, protein-protein interaction assays, immunofluorescence, sperm motility/hyperactivation analysis, Western blot for phosphorylation","journal":"Biology of Reproduction","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — domain mutagenesis in vivo with defined localization and functional phosphorylation readouts, single lab with multiple orthogonal methods","pmids":["38145487"],"is_preprint":false}],"current_model":"AKAP3 is a dual-specificity scaffolding protein of the sperm fibrous sheath that anchors both type-I (RIα) and type-II (RIIα) PKA regulatory subunits via two conserved N-terminal amphipathic domains, organizes a local cAMP-signaling complex including PDE4A5 and CABYR/Ropporin, is directly phosphorylated by STK33 kinase and undergoes capacitation-regulated tyrosine phosphorylation and proteasomal degradation (with PKARII binding protecting it from degradation), and is essential for fibrous sheath integrity, PKA-mediated sperm hyperactivation, and male fertility; additionally, activated Gα13 can bind AKAP3 to release catalytic PKA in a cAMP-independent manner."},"narrative":{"mechanistic_narrative":"AKAP3 (AKAP110/FSP95/SOB1) is a sperm-specific A-kinase anchoring protein that scaffolds a local cAMP-signaling complex within the fibrous sheath of the sperm flagellum and is essential for fibrous sheath integrity, sperm motility, and male fertility [PMID:10319321, PMID:31969357]. Through two conserved N-terminal amphipathic domains it functions as a dual-specificity anchor for both RIα and RIIα regulatory subunits of PKA, switching anchoring preference across spermiogenesis—favoring RIα in elongating spermatids and co-localizing with RIIα in the principal piece of mature sperm [PMID:24687590]; deletion of these domains mislocalizes RIα, reduces PKA substrate phosphorylation, and abolishes capacitation-induced hyperactivation [PMID:38145487]. AKAP3 organizes additional members of this signaling module, selectively binding the phosphodiesterase PDE4A5 to control local cAMP levels [PMID:16177223] and recruiting CABYR and Ropporin into a fibrous-sheath complex [PMID:21240291]. Bicarbonate- and soluble adenylate cyclase-driven cAMP signaling promotes capacitation-associated tyrosine phosphorylation of AKAP3 and enhanced PKA recruitment, increasing motility and hyperactivation [PMID:15342355], and activated Gα13 can bind AKAP3 to release catalytic PKA in a cAMP-independent manner [PMID:11696326]. AKAP3 is a direct substrate of the kinase STK33, whose loss reduces AKAP3 levels and disrupts fibrous sheath assembly [PMID:37146716], and its abundance is regulated during capacitation by ubiquitin-proteasome-mediated degradation that is governed by its tyrosine-phosphorylation status and protected by bound PKARII, with AKAP3 turnover being required for the acrosome reaction [PMID:23894359, PMID:26093290, PMID:36209601].","teleology":[{"year":1999,"claim":"Established AKAP3 as a sperm-specific PKA anchor by mapping its RII-binding amphipathic helix and demonstrating co-compartmentalization with PKA regulatory subunits, defining its core scaffolding function.","evidence":"Truncated mutant binding assays, immunocytochemistry, Northern blot across mouse/bovine/human","pmids":["10319321"],"confidence":"High","gaps":["Functional consequence of PKA anchoring not yet tested","RI versus RII selectivity not resolved"]},{"year":1999,"claim":"Localized AKAP3 to the ribs of the fibrous sheath and showed it is tyrosine-phosphorylated during capacitation, linking the anchor to capacitation signaling.","evidence":"Immunoelectron microscopy, indirect immunofluorescence, Western blot in human sperm","pmids":["10529264"],"confidence":"High","gaps":["Kinase responsible for tyrosine phosphorylation not identified","Functional role of phosphorylation undefined"]},{"year":2001,"claim":"Revealed a cAMP-independent route to PKA activation in which activated Gα13 binds AKAP3 to release catalytic PKA, expanding the regulatory logic of the scaffold.","evidence":"Yeast two-hybrid, in vitro binding, co-IP, PKA activity assay","pmids":["11696326"],"confidence":"High","gaps":["Physiological context of Gα13 activation in sperm unclear","In vivo relevance not tested"]},{"year":2004,"claim":"Connected upstream bicarbonate/sAC-driven cAMP production to AKAP3 tyrosine phosphorylation and PKA recruitment, tying the scaffold to motility and hyperactivation.","evidence":"Western blot, pharmacological inhibition of sAC/PI3K, sperm motility analysis","pmids":["15342355"],"confidence":"Medium","gaps":["No mutagenesis or reconstitution","Direct phosphorylation sites not mapped"]},{"year":2005,"claim":"Showed AKAP3 selectively scaffolds PDE4A5 over PDE4D, establishing it as an organizer of local cAMP degradation as well as PKA anchoring.","evidence":"Co-IP in COS cells, pulldown from sperm lysates, immunolocalization","pmids":["16177223"],"confidence":"High","gaps":["PDE-binding domain on AKAP3 not mapped","Functional impact on local cAMP gradients not directly measured"]},{"year":2011,"claim":"Defined AKAP3 as the organizing hub of a CABYR/Ropporin complex in the fibrous sheath, with CABYR binding via an RII-like domain.","evidence":"Co-IP, mass spectrometry, yeast two-hybrid in human sperm","pmids":["21240291"],"confidence":"High","gaps":["Functional role of the complex not established","Calcium dependence of assembly untested"]},{"year":2013,"claim":"Identified proteasomal degradation of AKAP3 during capacitation and showed PKARII anchoring protects it, linking scaffold stability to PKA occupancy.","evidence":"Western blot, MG-132, Ht31 peptide disruption, PKA modulators in bovine sperm","pmids":["23894359"],"confidence":"Medium","gaps":["E3 ligase not identified","Mechanism inferred from inhibitors without reconstitution"]},{"year":2014,"claim":"Resolved AKAP3 as a dual-specificity anchor with distinct 'dual' and 'RI' amphipathic domains and a developmental switch from RIα to RIIα preference across spermiogenesis.","evidence":"Domain mutagenesis, in vivo/in vitro binding, immunofluorescence, co-IP","pmids":["24687590"],"confidence":"High","gaps":["Mechanism controlling the developmental anchoring switch unknown","Functional consequence of dual specificity not yet tested in vivo"]},{"year":2014,"claim":"Connected AKAP3 protein synthesis to PKA signaling and RNA-binding proteins at the chromatoid body, showing translational rather than transcriptional control during spermiogenesis.","evidence":"Co-IP/MS, RNA EMSA, sucrose gradient, immunofluorescence, PKA activator treatment","pmids":["24648398"],"confidence":"Medium","gaps":["Direct RBP binding to Akap3 mRNA not mapped to specific elements","Single lab"]},{"year":2015,"claim":"Demonstrated that capacitation-associated tyrosine dephosphorylation controls AKAP3 degradation rate and that AKAP3 turnover is required for the acrosome reaction.","evidence":"IP, Western blot, tyrosine kinase/phosphatase inhibitors, anti-AKAP3 antibody microinjection, acrosome reaction assay","pmids":["26093290"],"confidence":"Medium","gaps":["Phosphatase/kinase identities unresolved","Mechanism linking turnover to acrosome reaction unclear"]},{"year":2019,"claim":"Showed an oviductal signal (rHuOVGP1) enhances AKAP3 tyrosine phosphorylation during capacitation, placing the scaffold downstream of the female reproductive tract environment.","evidence":"Western blot, immunoprecipitation, confocal immunofluorescence","pmids":["31254143"],"confidence":"Medium","gaps":["Receptor/signaling link to AKAP3 unmapped","Single lab, lower-tier evidence"]},{"year":2020,"claim":"Genetic ablation established AKAP3 as essential for fibrous sheath formation, sperm motility, correct PKA subunit localization, and male fertility, with F-actin accumulation during epididymal maturation.","evidence":"Akap3 knockout mice, proteomics, immunofluorescence, electron microscopy, motility analysis","pmids":["31969357"],"confidence":"High","gaps":["Mechanism linking loss to F-actin accumulation unclear","Which proteome changes are causal versus secondary undefined"]},{"year":2022,"claim":"Defined the ubiquitin-26S proteasome pathway as the degradation route for AKAP3, showing proteasome inhibition uncouples PKA from AKAP3 and shifts the sperm phosphorylation landscape.","evidence":"Co-precipitation, Western blot, MG132, flow cytometry","pmids":["36209601"],"confidence":"Medium","gaps":["Specific ubiquitination sites and E3 ligase not identified","Single lab"]},{"year":2023,"claim":"Identified AKAP3 as a direct substrate of STK33 kinase, providing an upstream regulator whose loss reduces AKAP3 and disrupts fibrous sheath assembly.","evidence":"Phosphoproteomics, in vitro kinase assay, Stk33 KO/KI mice, Western blot, electron microscopy","pmids":["37146716"],"confidence":"High","gaps":["STK33 phosphosite on AKAP3 not mapped","Functional effect of the phosphorylation on anchoring not tested"]},{"year":2024,"claim":"Demonstrated in vivo that the dual and RI amphipathic domains are required for correct RIα localization, PKA substrate phosphorylation, hyperactivation, and fertility, cementing PKA anchoring as the core fertility-relevant function.","evidence":"Domain deletion mutant mice, interaction assays, immunofluorescence, motility/hyperactivation, Western blot","pmids":["38145487"],"confidence":"High","gaps":["How RIα anchoring drives hyperactivation mechanistically unclear","Distinct roles of dual versus RI domains not fully separated"]},{"year":null,"claim":"The identity of the E3 ubiquitin ligase that targets AKAP3 and the precise mechanism by which AKAP3-anchored PKA drives flagellar hyperactivation remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No E3 ligase identified for AKAP3 degradation","Mechanistic link from local PKA activity to axonemal motility undefined","Structural model of the AKAP3 signaling complex absent"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,8,14]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[2,6,4]}],"localization":[{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[1,11]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[11]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,2,3]},{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[11,14]}],"complexes":["sperm fibrous sheath","AKAP3-PKA-PDE4A5 cAMP-signaling complex","AKAP3-CABYR-Ropporin complex"],"partners":["PRKAR1A","PRKAR2A","PDE4A5","CABYR","ROPN1","GNA13","STK33"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O75969","full_name":"A-kinase anchor protein 3","aliases":["A-kinase anchor protein 110 kDa","AKAP 110","Cancer/testis antigen 82","CT82","Fibrous sheath protein of 95 kDa","FSP95","Fibrousheathin I","Fibrousheathin-1","Protein kinase A-anchoring protein 3","PRKA3","Sperm oocyte-binding protein"],"length_aa":853,"mass_kda":94.8,"function":"Structural component of sperm fibrous sheath (By similarity). Required for the formation of the subcellular structure of the sperm flagellum, sperm motility and male fertility (PubMed:35228300)","subcellular_location":"Cytoplasmic vesicle, secretory vesicle, acrosome; Cell projection, cilium, flagellum","url":"https://www.uniprot.org/uniprotkb/O75969/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/AKAP3","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/AKAP3","total_profiled":1310},"omim":[{"mim_id":"620849","title":"SPERMATOGENIC FAILURE 93; SPGF93","url":"https://www.omim.org/entry/620849"},{"mim_id":"620354","title":"SPERMATOGENIC FAILURE 83; SPGF83","url":"https://www.omim.org/entry/620354"},{"mim_id":"620353","title":"SPERMATOGENIC FAILURE 82; SPGF82","url":"https://www.omim.org/entry/620353"},{"mim_id":"618304","title":"GLUTAMINE-RICH PROTEIN 2; QRICH2","url":"https://www.omim.org/entry/618304"},{"mim_id":"612911","title":"NADH DEHYDROGENASE (UBIQUINONE) COMPLEX I, ASSEMBLY FACTOR 3; NDUFAF3","url":"https://www.omim.org/entry/612911"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Vesicles","reliability":"Approved"},{"location":"Cytosol","reliability":"Additional"},{"location":"Principal piece","reliability":"Additional"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"testis","ntpm":93.5}],"url":"https://www.proteinatlas.org/search/AKAP3"},"hgnc":{"alias_symbol":["FSP95","SOB1","AKAP110","CT82"],"prev_symbol":[]},"alphafold":{"accession":"O75969","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O75969","model_url":"https://alphafold.ebi.ac.uk/files/AF-O75969-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O75969-F1-predicted_aligned_error_v6.png","plddt_mean":50.59},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=AKAP3","jax_strain_url":"https://www.jax.org/strain/search?query=AKAP3"},"sequence":{"accession":"O75969","fasta_url":"https://rest.uniprot.org/uniprotkb/O75969.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O75969/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O75969"}},"corpus_meta":[{"pmid":"10319321","id":"PMC_10319321","title":"Isolation and molecular characterization of AKAP110, a novel, sperm-specific protein kinase A-anchoring protein.","date":"1999","source":"Molecular endocrinology (Baltimore, Md.)","url":"https://pubmed.ncbi.nlm.nih.gov/10319321","citation_count":147,"is_preprint":false},{"pmid":"10529264","id":"PMC_10529264","title":"FSP95, a testis-specific 95-kilodalton fibrous sheath antigen that undergoes tyrosine phosphorylation in capacitated human spermatozoa.","date":"1999","source":"Biology of reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/10529264","citation_count":144,"is_preprint":false},{"pmid":"15342355","id":"PMC_15342355","title":"Tyrosine phosphorylation of the a kinase anchoring protein 3 (AKAP3) and soluble adenylate cyclase are involved in the increase of human sperm motility by bicarbonate.","date":"2004","source":"Biology of reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/15342355","citation_count":89,"is_preprint":false},{"pmid":"11229805","id":"PMC_11229805","title":"Molecular genetic analysis of two human sperm fibrous sheath proteins, AKAP4 and AKAP3, in men with dysplasia of the fibrous sheath.","date":"2001","source":"Journal of andrology","url":"https://pubmed.ncbi.nlm.nih.gov/11229805","citation_count":81,"is_preprint":false},{"pmid":"31969357","id":"PMC_31969357","title":"Lack of AKAP3 disrupts integrity of the subcellular structure and proteome of mouse sperm and causes male sterility.","date":"2020","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/31969357","citation_count":68,"is_preprint":false},{"pmid":"11696326","id":"PMC_11696326","title":"Interaction of heterotrimeric G13 protein with an A-kinase-anchoring protein 110 (AKAP110) mediates cAMP-independent PKA activation.","date":"2001","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/11696326","citation_count":66,"is_preprint":false},{"pmid":"16177223","id":"PMC_16177223","title":"AKAP3 selectively binds PDE4A isoforms in bovine spermatozoa.","date":"2005","source":"Biology of 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1499T>C Variant in The AKAP3 Gene of Infertile Men with Multiple Morphological Abnormalities of The Sperm Flagella Phenotype: A Case-Control Study.","date":"2024","source":"International journal of fertility & sterility","url":"https://pubmed.ncbi.nlm.nih.gov/38368523","citation_count":3,"is_preprint":false},{"pmid":"32681621","id":"PMC_32681621","title":"Prediction of 3D Protein Structure Based on The Mutation of AKAP3 and PLOD3 Genes in The Case of Non-Obstructive Azoospermia.","date":"2020","source":"International journal of fertility & sterility","url":"https://pubmed.ncbi.nlm.nih.gov/32681621","citation_count":2,"is_preprint":false},{"pmid":"31074059","id":"PMC_31074059","title":"Differential expression of TLRs and AKAP3 in cigarette smoked mice testis.","date":"2019","source":"Andrologia","url":"https://pubmed.ncbi.nlm.nih.gov/31074059","citation_count":1,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.11.26.625329","title":"An updated reference genome sequence and annotation reveals gene losses and gains underlying naked mole-rat biology","date":"2024-11-28","source":"bioRxiv","url":"https://doi.org/10.1101/2024.11.26.625329","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":16367,"output_tokens":3915,"usd":0.053913,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":11690,"output_tokens":4351,"usd":0.083613,"stage2_stop_reason":"end_turn"},"total_usd":0.137526,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1999,\n      \"finding\": \"AKAP3 (AKAP110) is a sperm-specific A-kinase anchoring protein whose RII-binding domain was mapped using truncated mutants; the domain forms an amphipathic helix with eight conserved positions responsible for RII interaction. AKAP3 localizes to the acrosomal region of the sperm head and along the entire principal piece, co-compartmentalizing with both RI and RII regulatory subunits of PKA.\",\n      \"method\": \"Truncated mutant binding assays, immunocytochemistry, Northern blot, in situ hybridization\",\n      \"journal\": \"Molecular Endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — RII-binding domain mapped by mutagenesis, localization confirmed by immunocytochemistry, replicated across mouse/bovine/human\",\n      \"pmids\": [\"10319321\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"AKAP3 (FSP95/SOB1) is localized to the ribs of the fibrous sheath in the principal piece of the human sperm tail, as determined by indirect immunofluorescence and immunoelectron microscopy. AKAP3 undergoes tyrosine phosphorylation during capacitation of human spermatozoa.\",\n      \"method\": \"Immunoelectron microscopy, indirect immunofluorescence, Western blot\",\n      \"journal\": \"Biology of Reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — subcellular localization established by immunoelectron microscopy with functional context (capacitation), replicated by independent lab\",\n      \"pmids\": [\"10529264\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Activated Gα13 (heterotrimeric G protein α subunit) directly interacts with AKAP3 (AKAP110), forming a complex with both the regulatory (rPKA) and catalytic (cPKA) subunits of PKA. Gα13 binding to AKAP3 releases the catalytic subunit of PKA from the AKAP3-rPKA complex, resulting in cAMP-independent PKA activation; AKAP110 potentiates this Gα13-induced PKA activation.\",\n      \"method\": \"Yeast two-hybrid screening, in vitro binding assay, co-immunoprecipitation, PKA activity assay\",\n      \"journal\": \"Current Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — yeast two-hybrid discovery confirmed by in vitro binding and co-IP, functional consequence (PKA activation) measured in same study\",\n      \"pmids\": [\"11696326\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Bicarbonate stimulates tyrosine phosphorylation of AKAP3 in human spermatozoa through activation of soluble adenylate cyclase (sAC), leading to increased cAMP production and enhanced recruitment of PKA to AKAP3, and this signaling cascade increases sperm motility and hyperactivation.\",\n      \"method\": \"Western blot, pharmacological inhibition (sAC inhibitor 2OH-estradiol, DIDS, LY294002), sperm motility analysis\",\n      \"journal\": \"Biology of Reproduction\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological dissection with multiple inhibitors in single lab, no mutagenesis or reconstitution\",\n      \"pmids\": [\"15342355\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"AKAP3 selectively binds PDE4A5 (but not PDE4D) isoform in bovine spermatozoa, as demonstrated by co-immunoprecipitation in COS cells co-transfected with AKAP3 and PDE isoforms, and confirmed by pulldown from sperm lysates. AKAP3 functions as a scaffolding protein that co-localizes with PDE4A in the principal piece to regulate local cAMP concentrations.\",\n      \"method\": \"Co-immunoprecipitation (COS cell co-transfection), pulldown assay from sperm lysates, immunolocalization\",\n      \"journal\": \"Biology of Reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — interaction confirmed by two orthogonal methods (COS cell co-IP and sperm lysate pulldown), isoform selectivity tested in same study\",\n      \"pmids\": [\"16177223\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"AKAP3 forms a complex with CABYR (calcium-binding tyrosine phosphorylation-regulated protein) and Ropporin in the human sperm fibrous sheath. CABYR binds AKAP3 via its RII-like domain, as confirmed by co-immunoprecipitation and yeast two-hybrid assays.\",\n      \"method\": \"Co-immunoprecipitation, mass spectrometry, Western blot, yeast two-hybrid\",\n      \"journal\": \"Asian Journal of Andrology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP confirmed by yeast two-hybrid, two orthogonal methods in single study\",\n      \"pmids\": [\"21240291\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"AKAP3 is degraded via the proteasomal machinery during bovine sperm capacitation (inhibited by MG-132). Binding of PKARII to AKAP3 protects AKAP3 from degradation; disruption of PKARII anchoring (with Ht31 peptide) or inhibition/activation of PKA both increase AKAP3 degradation rate. Intracellular alkalization (NH4Cl) also enhances AKAP3 degradation.\",\n      \"method\": \"Western blot, proteasome inhibitor (MG-132), Ht31 peptide disruption, PKA activity modulators (H89, 8Br-cAMP), calcium chelation\",\n      \"journal\": \"PLoS ONE\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple pharmacological interventions in single lab, mechanism inferred from inhibitor studies without direct reconstitution\",\n      \"pmids\": [\"23894359\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"AKAP3 synthesis during mouse spermiogenesis is regulated by PKA signaling and RNA-binding proteins (RBPs) PIWIL1, PABPC1, and NONO. Nascent AKAP3 forms a protein complex with PKA and these RBPs, which co-localize at the chromatoid body. Activation of PKA positively regulates AKAP3 protein synthesis without changing mRNA levels in elongating spermatids.\",\n      \"method\": \"Co-immunoprecipitation, protein mass spectrometry, RNA EMSA, sucrose gradient sedimentation, immunofluorescence, PKA activator treatment\",\n      \"journal\": \"Biology of Reproduction\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP/MS identification of complex confirmed by functional PKA activation experiment, single lab\",\n      \"pmids\": [\"24648398\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"AKAP3 is a dual-specificity anchoring protein that interacts with both RIα and RIIα regulatory subunits of PKA via two conserved N-terminal amphipathic peptide domains (named 'dual' and 'RI' domains). In elongating spermatids AKAP3 interacts preferentially with RIα, while in mature sperm it co-localizes exclusively with RIIα in the principal piece.\",\n      \"method\": \"Mutagenesis of amphipathic domains, in vivo and in vitro binding assays, immunofluorescence, co-immunoprecipitation\",\n      \"journal\": \"Molecular Reproduction and Development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — domain mutagenesis combined with in vitro binding and in vivo co-IP, localization confirmed by immunofluorescence\",\n      \"pmids\": [\"24687590\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"AKAP3 undergoes tyrosine dephosphorylation during sperm capacitation, and its degradation rate is regulated by its tyrosine phosphorylation status: inhibition of tyrosine phosphatase reduces AKAP3 degradation, while inhibition of tyrosine kinase enhances it. Blocking AKAP3 degradation with anti-AKAP3 antibody in permeabilized cells inhibits the acrosome reaction, demonstrating that AKAP3 degradation is required for capacitation.\",\n      \"method\": \"Immunoprecipitation, Western blot, tyrosine kinase/phosphatase inhibitors, anti-AKAP3 antibody microinjection into permeabilized cells, FITC-PSA acrosome reaction assay\",\n      \"journal\": \"Biochimica et Biophysica Acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple pharmacological perturbations plus functional antibody blockade, single lab\",\n      \"pmids\": [\"26093290\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Recombinant human oviduct-specific glycoprotein (rHuOVGP1) enhances tyrosine phosphorylation of AKAP3 in the fibrous sheath during capacitation, as shown by co-migration of the pY 105 kDa band with AKAP3 on Western blot and confirmed by immunoprecipitation and co-localization by immunofluorescence.\",\n      \"method\": \"Western blot, immunoprecipitation, confocal immunofluorescence\",\n      \"journal\": \"Journal of Assisted Reproduction and Genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP and co-localization confirmed by two orthogonal methods in single lab\",\n      \"pmids\": [\"31254143\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Genetic ablation of AKAP3 in mice causes male sterility due to defects in fibrous sheath formation, loss of sperm motility, and global proteome changes in sperm including mislocalization of PKA subunits and accumulation of RNA metabolism/translation factors. Sperm from both Akap3 and Akap4 null mice accumulate F-actin filaments during post-testicular epididymal maturation.\",\n      \"method\": \"Mouse knockout (Akap3 null), proteomics, immunofluorescence, electron microscopy, sperm motility analysis\",\n      \"journal\": \"Development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO with multiple orthogonal phenotypic readouts including proteomics and structural analysis\",\n      \"pmids\": [\"31969357\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"AKAP3 is degraded by the ubiquitin-26S proteasome pathway during sperm capacitation; inhibition of the 26S proteasome with MG132 causes accumulation of ubiquitinated AKAP3 and uncoupling of PKA from AKAP3, leading to PKA degradation by UPP, reduced tyrosine phosphorylation, and increased serine/threonine phosphorylation.\",\n      \"method\": \"Co-precipitation assays, Western blot, proteasome inhibitor (MG132), flow cytometry\",\n      \"journal\": \"Animal Reproduction Science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-precipitation and pharmacological inhibition, single lab, consistent with earlier MG132 data\",\n      \"pmids\": [\"36209601\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"STK33 kinase directly phosphorylates AKAP3 (and AKAP4); differential phosphoproteomic analysis and in vitro kinase assay identified AKAP3 as a novel phosphorylation substrate of STK33. Loss of STK33 reduces AKAP3 expression in testis and disrupts fibrous sheath assembly in sperm.\",\n      \"method\": \"Differential phosphoproteomics, in vitro kinase assay, Stk33 knockout/knock-in mice, Western blot, electron microscopy\",\n      \"journal\": \"Molecular & Cellular Proteomics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro kinase assay identifies AKAP3 as direct STK33 substrate, confirmed by phosphoproteomics and KO mouse phenotype in single rigorous study\",\n      \"pmids\": [\"37146716\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"The dual and RI amphipathic domains in the N-terminus of AKAP3, responsible for binding RIα and RIIα of PKA, are required for sperm hyperactivation and male fertility. Deletion of these domains in mice causes RIα mislocalization from the principal piece to the midpiece of the sperm tail, reduces PKA substrate phosphorylation, and abolishes hyperactivation under capacitation conditions, without altering PKA subunit protein levels. AKAP3 shows a preference for binding RIα over RIIα.\",\n      \"method\": \"Domain deletion mutant mice, protein-protein interaction assays, immunofluorescence, sperm motility/hyperactivation analysis, Western blot for phosphorylation\",\n      \"journal\": \"Biology of Reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — domain mutagenesis in vivo with defined localization and functional phosphorylation readouts, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"38145487\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"AKAP3 is a dual-specificity scaffolding protein of the sperm fibrous sheath that anchors both type-I (RIα) and type-II (RIIα) PKA regulatory subunits via two conserved N-terminal amphipathic domains, organizes a local cAMP-signaling complex including PDE4A5 and CABYR/Ropporin, is directly phosphorylated by STK33 kinase and undergoes capacitation-regulated tyrosine phosphorylation and proteasomal degradation (with PKARII binding protecting it from degradation), and is essential for fibrous sheath integrity, PKA-mediated sperm hyperactivation, and male fertility; additionally, activated Gα13 can bind AKAP3 to release catalytic PKA in a cAMP-independent manner.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"AKAP3 (AKAP110/FSP95/SOB1) is a sperm-specific A-kinase anchoring protein that scaffolds a local cAMP-signaling complex within the fibrous sheath of the sperm flagellum and is essential for fibrous sheath integrity, sperm motility, and male fertility [#0, #11]. Through two conserved N-terminal amphipathic domains it functions as a dual-specificity anchor for both RIα and RIIα regulatory subunits of PKA, switching anchoring preference across spermiogenesis—favoring RIα in elongating spermatids and co-localizing with RIIα in the principal piece of mature sperm [#8]; deletion of these domains mislocalizes RIα, reduces PKA substrate phosphorylation, and abolishes capacitation-induced hyperactivation [#14]. AKAP3 organizes additional members of this signaling module, selectively binding the phosphodiesterase PDE4A5 to control local cAMP levels [#4] and recruiting CABYR and Ropporin into a fibrous-sheath complex [#5]. Bicarbonate- and soluble adenylate cyclase-driven cAMP signaling promotes capacitation-associated tyrosine phosphorylation of AKAP3 and enhanced PKA recruitment, increasing motility and hyperactivation [#3], and activated Gα13 can bind AKAP3 to release catalytic PKA in a cAMP-independent manner [#2]. AKAP3 is a direct substrate of the kinase STK33, whose loss reduces AKAP3 levels and disrupts fibrous sheath assembly [#13], and its abundance is regulated during capacitation by ubiquitin-proteasome-mediated degradation that is governed by its tyrosine-phosphorylation status and protected by bound PKARII, with AKAP3 turnover being required for the acrosome reaction [#6, #9, #12].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Established AKAP3 as a sperm-specific PKA anchor by mapping its RII-binding amphipathic helix and demonstrating co-compartmentalization with PKA regulatory subunits, defining its core scaffolding function.\",\n      \"evidence\": \"Truncated mutant binding assays, immunocytochemistry, Northern blot across mouse/bovine/human\",\n      \"pmids\": [\"10319321\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of PKA anchoring not yet tested\", \"RI versus RII selectivity not resolved\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Localized AKAP3 to the ribs of the fibrous sheath and showed it is tyrosine-phosphorylated during capacitation, linking the anchor to capacitation signaling.\",\n      \"evidence\": \"Immunoelectron microscopy, indirect immunofluorescence, Western blot in human sperm\",\n      \"pmids\": [\"10529264\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinase responsible for tyrosine phosphorylation not identified\", \"Functional role of phosphorylation undefined\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Revealed a cAMP-independent route to PKA activation in which activated Gα13 binds AKAP3 to release catalytic PKA, expanding the regulatory logic of the scaffold.\",\n      \"evidence\": \"Yeast two-hybrid, in vitro binding, co-IP, PKA activity assay\",\n      \"pmids\": [\"11696326\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological context of Gα13 activation in sperm unclear\", \"In vivo relevance not tested\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Connected upstream bicarbonate/sAC-driven cAMP production to AKAP3 tyrosine phosphorylation and PKA recruitment, tying the scaffold to motility and hyperactivation.\",\n      \"evidence\": \"Western blot, pharmacological inhibition of sAC/PI3K, sperm motility analysis\",\n      \"pmids\": [\"15342355\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No mutagenesis or reconstitution\", \"Direct phosphorylation sites not mapped\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Showed AKAP3 selectively scaffolds PDE4A5 over PDE4D, establishing it as an organizer of local cAMP degradation as well as PKA anchoring.\",\n      \"evidence\": \"Co-IP in COS cells, pulldown from sperm lysates, immunolocalization\",\n      \"pmids\": [\"16177223\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"PDE-binding domain on AKAP3 not mapped\", \"Functional impact on local cAMP gradients not directly measured\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Defined AKAP3 as the organizing hub of a CABYR/Ropporin complex in the fibrous sheath, with CABYR binding via an RII-like domain.\",\n      \"evidence\": \"Co-IP, mass spectrometry, yeast two-hybrid in human sperm\",\n      \"pmids\": [\"21240291\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional role of the complex not established\", \"Calcium dependence of assembly untested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identified proteasomal degradation of AKAP3 during capacitation and showed PKARII anchoring protects it, linking scaffold stability to PKA occupancy.\",\n      \"evidence\": \"Western blot, MG-132, Ht31 peptide disruption, PKA modulators in bovine sperm\",\n      \"pmids\": [\"23894359\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"E3 ligase not identified\", \"Mechanism inferred from inhibitors without reconstitution\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Resolved AKAP3 as a dual-specificity anchor with distinct 'dual' and 'RI' amphipathic domains and a developmental switch from RIα to RIIα preference across spermiogenesis.\",\n      \"evidence\": \"Domain mutagenesis, in vivo/in vitro binding, immunofluorescence, co-IP\",\n      \"pmids\": [\"24687590\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism controlling the developmental anchoring switch unknown\", \"Functional consequence of dual specificity not yet tested in vivo\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Connected AKAP3 protein synthesis to PKA signaling and RNA-binding proteins at the chromatoid body, showing translational rather than transcriptional control during spermiogenesis.\",\n      \"evidence\": \"Co-IP/MS, RNA EMSA, sucrose gradient, immunofluorescence, PKA activator treatment\",\n      \"pmids\": [\"24648398\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct RBP binding to Akap3 mRNA not mapped to specific elements\", \"Single lab\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Demonstrated that capacitation-associated tyrosine dephosphorylation controls AKAP3 degradation rate and that AKAP3 turnover is required for the acrosome reaction.\",\n      \"evidence\": \"IP, Western blot, tyrosine kinase/phosphatase inhibitors, anti-AKAP3 antibody microinjection, acrosome reaction assay\",\n      \"pmids\": [\"26093290\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Phosphatase/kinase identities unresolved\", \"Mechanism linking turnover to acrosome reaction unclear\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Showed an oviductal signal (rHuOVGP1) enhances AKAP3 tyrosine phosphorylation during capacitation, placing the scaffold downstream of the female reproductive tract environment.\",\n      \"evidence\": \"Western blot, immunoprecipitation, confocal immunofluorescence\",\n      \"pmids\": [\"31254143\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Receptor/signaling link to AKAP3 unmapped\", \"Single lab, lower-tier evidence\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Genetic ablation established AKAP3 as essential for fibrous sheath formation, sperm motility, correct PKA subunit localization, and male fertility, with F-actin accumulation during epididymal maturation.\",\n      \"evidence\": \"Akap3 knockout mice, proteomics, immunofluorescence, electron microscopy, motility analysis\",\n      \"pmids\": [\"31969357\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking loss to F-actin accumulation unclear\", \"Which proteome changes are causal versus secondary undefined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined the ubiquitin-26S proteasome pathway as the degradation route for AKAP3, showing proteasome inhibition uncouples PKA from AKAP3 and shifts the sperm phosphorylation landscape.\",\n      \"evidence\": \"Co-precipitation, Western blot, MG132, flow cytometry\",\n      \"pmids\": [\"36209601\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific ubiquitination sites and E3 ligase not identified\", \"Single lab\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified AKAP3 as a direct substrate of STK33 kinase, providing an upstream regulator whose loss reduces AKAP3 and disrupts fibrous sheath assembly.\",\n      \"evidence\": \"Phosphoproteomics, in vitro kinase assay, Stk33 KO/KI mice, Western blot, electron microscopy\",\n      \"pmids\": [\"37146716\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"STK33 phosphosite on AKAP3 not mapped\", \"Functional effect of the phosphorylation on anchoring not tested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Demonstrated in vivo that the dual and RI amphipathic domains are required for correct RIα localization, PKA substrate phosphorylation, hyperactivation, and fertility, cementing PKA anchoring as the core fertility-relevant function.\",\n      \"evidence\": \"Domain deletion mutant mice, interaction assays, immunofluorescence, motility/hyperactivation, Western blot\",\n      \"pmids\": [\"38145487\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How RIα anchoring drives hyperactivation mechanistically unclear\", \"Distinct roles of dual versus RI domains not fully separated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The identity of the E3 ubiquitin ligase that targets AKAP3 and the precise mechanism by which AKAP3-anchored PKA drives flagellar hyperactivation remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No E3 ligase identified for AKAP3 degradation\", \"Mechanistic link from local PKA activity to axonemal motility undefined\", \"Structural model of the AKAP3 signaling complex absent\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 8, 14]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [2, 6, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [1, 11]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [11]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 2, 3]},\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [11, 14]}\n    ],\n    \"complexes\": [\"sperm fibrous sheath\", \"AKAP3-PKA-PDE4A5 cAMP-signaling complex\", \"AKAP3-CABYR-Ropporin complex\"],\n    \"partners\": [\"PRKAR1A\", \"PRKAR2A\", \"PDE4A5\", \"CABYR\", \"ROPN1\", \"GNA13\", \"STK33\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}