{"gene":"PLCZ1","run_date":"2026-04-28T19:45:44","timeline":{"discoveries":[{"year":2002,"finding":"PLCζ (PLCZ1) is a sperm-specific phospholipase C that, when introduced into mammalian eggs, triggers a series of intracellular Ca²⁺ oscillations indistinguishable from those at fertilization by hydrolyzing PIP2 and generating InsP3, thereby initiating egg activation and embryo development.","method":"cRNA microinjection into mouse oocytes; Ca²⁺ imaging; identification of novel sperm-specific PLC isoform","journal":"Reproduction (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 1-2 — replicated across multiple labs and species with cRNA injection, Ca²⁺ imaging, and recombinant protein assays","pmids":["12416999","15047934"],"is_preprint":false},{"year":2003,"finding":"Recombinant PLCζ protein has an exceptionally high Ca²⁺ sensitivity (EC50 ~52 nM) for PIP2-hydrolyzing activity in vitro, approximately 100-fold higher than PLCδ1 (EC50 ~5.7 µM), enabling it to be active at resting intracellular Ca²⁺ levels (~100 nM).","method":"In vitro PIP2 hydrolysis assay at varying Ca²⁺ concentrations using baculovirus-expressed recombinant PLCζ; microinjection into mouse eggs","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro enzymatic reconstitution with purified recombinant protein, replicated by other labs","pmids":["14701816"],"is_preprint":false},{"year":2004,"finding":"PLCζ-induced Ca²⁺ oscillations occur exclusively during M phase and are regulated by nuclear sequestration: PLCζ localizes to pronuclei via a nuclear localization signal (NLS), and sequestration into the pronucleus terminates Ca²⁺ oscillations at the interphase of the first cell cycle.","method":"Live-cell imaging of fluorescently tagged PLCζ; NLS mutagenesis; inhibition of pronuclear formation","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 — direct localization experiments with functional consequence, NLS mutagenesis, multiple orthogonal approaches","pmids":["15159452"],"is_preprint":false},{"year":2005,"finding":"The EF-hand domains and C2 domain of PLCζ are essential for its enzymatic activity: deletion of the four EF-hand domains or the C2 domain abolishes PIP2-hydrolyzing activity. EF3 is responsible for high Ca²⁺ sensitivity, and the C2 domain has affinity for PI(3)P and PI(5)P, which negatively regulate PLCζ activity.","method":"Structure-function analysis via deletion mutagenesis; in vitro PIP2 hydrolysis assay; microinjection of mutant RNA into mouse eggs","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro enzymatic assay combined with domain deletion mutagenesis and in vivo Ca²⁺ oscillation assay","pmids":["15790568"],"is_preprint":false},{"year":2006,"finding":"The X/Y linker region of PLCζ contains a nuclear localization signal (NLS) at residues 374-381 critical for pronuclear translocation; unlike somatic PLCs, the PLCζ X/Y linker does not mediate auto-inhibition but is required for catalytic activity.","method":"Point mutagenesis of NLS residues; fluorescent protein tagging; cRNA injection into mouse eggs; COS-7 cell transfection","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — mutagenesis with functional readouts in eggs and somatic cells, orthogonal methods","pmids":["16854985"],"is_preprint":false},{"year":2011,"finding":"Unlike somatic PLC isoforms that hydrolyze plasma membrane PI(4,5)P2, PLCζ targets an intracellular pool of PI(4,5)P2 present on cortical vesicles inside the egg to generate InsP3 and trigger Ca²⁺ oscillations.","method":"GFP-tagged PH domain to monitor plasma membrane PI(4,5)P2; targeted depletion of plasma membrane vs. intracellular PI(4,5)P2 by Inp54p phosphatase; immunolocalization of PLCζ and PI(4,5)P2; catalytically inactive PLCζ co-localization","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal approaches showing PLCζ targets intracellular PI(4,5)P2 vesicles, confirmed by gain- and loss-of-function experiments","pmids":["22114355"],"is_preprint":false},{"year":2011,"finding":"The PLCζ X/Y-linker region, unlike in somatic PLCs where it causes auto-inhibition, is required for PLCζ enzymatic activity; deletion of the XY-linker significantly diminishes in vitro PIP2 hydrolysis and in vivo Ca²⁺-oscillation-inducing activity.","method":"In vitro PIP2 hydrolysis assay; cRNA injection into mouse eggs; deletion mutagenesis of XY-linker","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 — in vitro enzymatic reconstitution with mutagenesis and in vivo functional validation","pmids":["21767260"],"is_preprint":false},{"year":2004,"finding":"Transgenic RNAi knockdown of PLCζ in mouse sperm causes premature termination of Ca²⁺ oscillations after fertilization, reduced egg activation rates, and subfertility in vivo, demonstrating PLCζ is required for physiological Ca²⁺ oscillations.","method":"Transgenic shRNA expression in mice; in vitro fertilization with Ca²⁺ imaging; mating studies","journal":"Biology of reproduction","confidence":"High","confidence_rationale":"Tier 2 — genetic loss-of-function in vivo with defined molecular phenotype, later confirmed by full knockout","pmids":["15601914"],"is_preprint":false},{"year":2017,"finding":"PLCζ knockout (Plcz1⁻/⁻) mouse sperm completely fail to trigger Ca²⁺ oscillations in eggs and cause polyspermy, demonstrating PLCζ is the physiological trigger of Ca²⁺ oscillations at fertilization; Plcz1⁻/⁻ males are subfertile but not sterile, indicating an alternative route to egg activation exists.","method":"Gene knockout mice (Plcz1⁻/⁻); Ca²⁺ imaging after in vitro fertilization; in vivo mating studies","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 — definitive genetic knockout with specific molecular phenotype (loss of Ca²⁺ oscillations), replicated by accompanying studies","pmids":["28694258"],"is_preprint":false},{"year":2007,"finding":"PLCζ remains functionally active after proteolytic cleavage at its X/Y linker region; N-terminal and C-terminal fragments remain associated as functional complexes capable of inducing Ca²⁺ oscillations and embryo development.","method":"In vitro protease (V8) cleavage of PLCζ; immunodepletion; co-expression of cRNAs encoding PLCζ N- and C-terminal fragments in mouse eggs; PLC activity assay","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro cleavage assay combined with in vivo co-expression reconstitution and immunodepletion","pmids":["18028898"],"is_preprint":false},{"year":2004,"finding":"A point mutation in the catalytic region of human PLCζ (identified in an infertile patient) abolishes the ability of the protein to induce Ca²⁺ oscillations when microinjected into mouse oocytes, linking loss-of-function PLCζ mutations to male infertility.","method":"DNA sequencing; cRNA microinjection into mouse oocytes; Ca²⁺ imaging; immunofluorescence; sperm injection into mouse oocytes","journal":"Human reproduction (Oxford, England)","confidence":"High","confidence_rationale":"Tier 2 — functional validation of human mutation by mouse oocyte Ca²⁺ assay, corroborated by multiple subsequent studies","pmids":["19584136"],"is_preprint":false},{"year":2015,"finding":"A homozygous missense mutation in PLCZ1 (c.1465A>T; p.Ile489Phe) in the C2 domain causes absence of PLCζ protein in sperm, mislocalization of the protein when expressed in oocytes, and highly abnormal Ca²⁺ transients, preventing oocyte activation. This identifies the C2 domain as required for proper PLCζ targeting and function.","method":"Whole-exome sequencing; western blotting; immunofluorescence; microinjection into mouse GV and MII oocytes; Ca²⁺ imaging","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 — human disease mutation functionally validated with multiple orthogonal assays","pmids":["26721930"],"is_preprint":false},{"year":2013,"finding":"PLCζ/PLCδ1 chimera analysis demonstrates that the XY-linker and C2 domain of PLCζ are essential for Ca²⁺ oscillation-inducing activity in eggs; the XY-linker mediates binding to PIP2-containing liposomes, and the C2 domain mediates binding to PI(3)P-containing liposomes.","method":"Domain chimera construction; Ca²⁺ imaging in mouse eggs; in vitro PIP2 hydrolysis assay; liposome-binding assay; mathematical modeling","journal":"Molecular human reproduction","confidence":"High","confidence_rationale":"Tier 1 — in vitro biochemical assays combined with in vivo functional readout and domain-swap mutagenesis","pmids":["24152875"],"is_preprint":false},{"year":2011,"finding":"A male infertility-linked point mutation in human PLCζ introduced into mouse PLCζ completely abolishes in vitro PIP2 hydrolysis activity and in vivo Ca²⁺ oscillation-inducing ability; wild-type PLCζ initiates normal Ca²⁺ oscillations even in the presence of 10-fold excess mutant, ruling out a dominant-negative mechanism.","method":"In vitro PIP2 hydrolysis assay; cRNA microinjection into mouse eggs; Ca²⁺ imaging","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 — in vitro enzymatic assay and in vivo functional validation of human disease mutation","pmids":["21204786"],"is_preprint":false},{"year":2014,"finding":"PLCζ localizes along the inner acrosomal membrane and in the perinuclear theca (equatorial region) of normal human sperm; PLCζ is absent or greatly reduced in DPY19L2-deficient globozoospermic sperm (which lack acrosome and perinuclear theca), explaining failed Ca²⁺ oscillations and oocyte activation failure.","method":"Immunofluorescence localization in human and mouse sperm; Ca²⁺ imaging after ICSI with Dpy19l2 KO mouse sperm; western blotting","journal":"Molecular human reproduction","confidence":"High","confidence_rationale":"Tier 2 — direct subcellular localization with functional consequence in defined KO model","pmids":["25354701"],"is_preprint":false},{"year":2008,"finding":"Ca²⁺ oscillation-inducing activity and nuclear translocation ability differ significantly among PLCζ orthologs from mouse, rat, human, and medaka fish; mouse PLCZ1 enters pronuclei in mouse eggs while rat and human PLCZ1 show defective nuclear translocation in mouse eggs, demonstrating species-specific NLS function.","method":"cRNA injection of PLCZ1 orthologs into mouse and rat eggs; Ca²⁺ imaging; fluorescence nuclear localization assay; RT-PCR","journal":"Biology of reproduction","confidence":"Medium","confidence_rationale":"Tier 2 — orthogonal assays but single lab comparing species orthologs","pmids":["18322275"],"is_preprint":false},{"year":2012,"finding":"Recombinant wild-type human PLCζ protein, when microinjected into mouse oocytes, triggers characteristic Ca²⁺ oscillations and supports embryo development to the blastocyst stage; infertility-linked mutant forms of PLCζ display aberrant enzymatic activity and fail to activate oocytes, demonstrating PLCζ as a potential therapeutic agent.","method":"Recombinant protein expression in HEK293T cells; microinjection into mouse/human oocytes; Ca²⁺ imaging; in vitro PIP2 hydrolysis assay","journal":"Fertility and sterility","confidence":"High","confidence_rationale":"Tier 1-2 — recombinant protein with enzymatic and in vivo functional validation","pmids":["22999959"],"is_preprint":false}],"current_model":"PLCZ1 (PLCζ) is a sperm-specific phospholipase C that lacks a PH domain, is delivered into the egg cytoplasm upon gamete fusion, and catalyzes hydrolysis of PI(4,5)P2 on intracellular vesicles (not the plasma membrane) at nanomolar Ca²⁺ concentrations (EC50 ~52 nM) to generate InsP3, thereby triggering repetitive Ca²⁺ oscillations via the IP3 receptor pathway that initiate egg activation and embryogenesis; its activity depends on intact EF-hand (EF3 for Ca²⁺ sensitivity), XY-linker (required for catalysis and PIP2 binding), and C2 (required for activity and intracellular targeting) domains, and Ca²⁺ oscillations are terminated by PLCζ sequestration into the pronucleus via an NLS in the XY-linker region."},"narrative":{"teleology":[{"year":2002,"claim":"Identification of PLCζ as a novel sperm-specific phospholipase C resolved the long-standing question of the molecular identity of the sperm factor that triggers Ca²⁺ oscillations at fertilization.","evidence":"cRNA microinjection of newly cloned PLCZ1 into mouse oocytes recapitulated fertilization-like Ca²⁺ oscillations and egg activation","pmids":["12416999","15047934"],"confidence":"High","gaps":["Mechanism of PLCζ delivery from sperm to egg cytoplasm not defined","Whether PLCζ is the sole sperm-derived oocyte-activating factor remained unknown"]},{"year":2003,"claim":"Demonstration that PLCζ has ~100-fold higher Ca²⁺ sensitivity than PLCδ1 explained how it can function at resting intracellular Ca²⁺ concentrations without requiring receptor-mediated activation.","evidence":"In vitro PIP₂ hydrolysis assay with baculovirus-expressed recombinant PLCζ showed EC₅₀ ~52 nM vs ~5.7 µM for PLCδ1","pmids":["14701816"],"confidence":"High","gaps":["Structural basis for high Ca²⁺ sensitivity not resolved","Whether post-translational modifications modulate sensitivity in vivo unknown"]},{"year":2004,"claim":"Structure–function studies of PLCζ domains and the discovery of nuclear sequestration established how Ca²⁺ oscillations are both generated and terminated during the first cell cycle: EF-hand and C2 domains are essential for catalysis, while an NLS in the XY-linker drives pronuclear translocation that stops oscillations.","evidence":"Deletion mutagenesis with in vitro PIP₂ hydrolysis and oocyte Ca²⁺ imaging; live-cell tracking of fluorescently tagged PLCζ with NLS mutations","pmids":["15790568","15159452","16854985"],"confidence":"High","gaps":["Crystal structure of PLCζ not available","Mechanism by which C2 domain targets PLCζ to intracellular membranes not fully resolved"]},{"year":2004,"claim":"Transgenic RNAi knockdown of PLCζ in mouse sperm provided loss-of-function evidence that endogenous PLCζ is required for sustained Ca²⁺ oscillations and normal fertility in vivo.","evidence":"Transgenic shRNA in mice; IVF with Ca²⁺ imaging; mating studies showing subfertility","pmids":["15601914"],"confidence":"High","gaps":["Knockdown was incomplete, leaving open whether PLCζ is absolutely required","Residual fertility suggested alternative activation pathways"]},{"year":2009,"claim":"Identification and functional validation of a catalytic-domain mutation in an infertile patient established PLCζ loss-of-function as a cause of human male infertility due to oocyte activation failure.","evidence":"Sequencing of infertile patient; mutant cRNA microinjection into mouse oocytes abolished Ca²⁺ oscillations","pmids":["19584136"],"confidence":"High","gaps":["Number of patients studied was small","Genetic background and additional mutations not fully excluded"]},{"year":2011,"claim":"Discovery that PLCζ targets intracellular vesicular PI(4,5)P₂ rather than plasma membrane PIP₂ resolved why PLCζ lacks a PH domain and explained its unique mechanism among PLC isoforms.","evidence":"GFP-PH domain reporters, targeted PI(4,5)P₂ depletion by Inp54p phosphatase, immunolocalization of PLCζ on cortical vesicles","pmids":["22114355"],"confidence":"High","gaps":["Identity and biogenesis of the intracellular PIP₂-containing vesicles not characterized","Whether PLCζ also acts on other phosphoinositide pools in vivo unknown"]},{"year":2011,"claim":"Functional validation of a human infertility mutation in mouse PLCζ confirmed that loss of enzymatic activity is the disease mechanism and ruled out dominant-negative effects, clarifying the recessive inheritance pattern.","evidence":"In vitro PIP₂ hydrolysis assay and cRNA co-injection of wild-type and 10-fold excess mutant PLCζ into mouse oocytes","pmids":["21204786"],"confidence":"High","gaps":["Limited to one mutation; generalizability to other PLCZ1 variants not tested"]},{"year":2013,"claim":"Domain chimera analysis between PLCζ and PLCδ1 pinpointed the XY-linker as a PIP₂-binding module and the C2 domain as a PI(3)P-binding module, together conferring PLCζ's unique intracellular targeting and catalytic properties.","evidence":"PLCζ/PLCδ1 chimeras tested with liposome-binding assays, in vitro PIP₂ hydrolysis, and oocyte Ca²⁺ imaging","pmids":["24152875"],"confidence":"High","gaps":["Structural basis for XY-linker PIP₂ interaction not determined","Whether PI(3)P binding inhibits or redirects PLCζ in intact eggs unclear"]},{"year":2015,"claim":"A homozygous C2-domain mutation (p.Ile489Phe) causing protein absence in sperm and mislocalization in oocytes proved the C2 domain is essential for PLCζ stability, targeting, and oocyte activation in humans.","evidence":"Whole-exome sequencing of infertile patient; western blot; immunofluorescence; cRNA injection into mouse oocytes with Ca²⁺ imaging","pmids":["26721930"],"confidence":"High","gaps":["Whether the mutation destabilizes PLCζ globally or specifically disrupts C2-membrane interaction not distinguished"]},{"year":2017,"claim":"Complete genetic knockout of Plcz1 definitively established PLCζ as the physiological Ca²⁺ oscillation trigger at fertilization while revealing an alternative, PLCζ-independent route to egg activation that permits residual fertility.","evidence":"Plcz1⁻/⁻ knockout mice; IVF with Ca²⁺ imaging showing total loss of oscillations; in vivo mating showing subfertility but not sterility","pmids":["28694258"],"confidence":"High","gaps":["Identity of the alternative egg activation mechanism is unknown","Whether compensatory mechanisms are upregulated in knockout animals not tested"]},{"year":null,"claim":"The structural basis for PLCζ's uniquely high Ca²⁺ sensitivity, the identity of the intracellular PIP₂-containing vesicles it targets, and the mechanism of the alternative PLCζ-independent egg activation pathway remain unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No crystal or cryo-EM structure of PLCζ available","Molecular identity of intracellular PIP₂ vesicle compartment not defined","PLCζ-independent egg activation factor not identified"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,1,3,6,12,13]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[5,12]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[2,4,15]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[5]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0,5]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1,5]},{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[0,7,8]}],"complexes":[],"partners":["DPY19L2"],"other_free_text":[]},"mechanistic_narrative":"PLCZ1 encodes a sperm-specific phospholipase C (PLCζ) that serves as the physiological trigger of egg activation at fertilization by generating repetitive intracellular Ca²⁺ oscillations essential for embryogenesis. Upon delivery into the egg cytoplasm at gamete fusion, PLCζ hydrolyzes an intracellular pool of PI(4,5)P₂ on cortical vesicles—rather than plasma membrane PIP₂—to produce InsP₃, which releases Ca²⁺ via IP₃ receptors; its exceptionally high Ca²⁺ sensitivity (EC₅₀ ~52 nM) enables activity at resting cytoplasmic Ca²⁺ levels [PMID:14701816, PMID:22114355]. Enzymatic function requires intact EF-hand domains (EF3 for Ca²⁺ sensitivity), an XY-linker region that uniquely promotes rather than auto-inhibits catalysis, and a C2 domain necessary for intracellular targeting and activity; Ca²⁺ oscillations are terminated when PLCζ translocates into the pronucleus via an NLS within the XY-linker [PMID:15790568, PMID:16854985, PMID:15159452]. Loss-of-function mutations in human PLCZ1 cause oocyte activation failure and male infertility, as demonstrated by patient mutation studies and confirmed by Plcz1-knockout mice that completely lack fertilization-triggered Ca²⁺ oscillations [PMID:19584136, PMID:26721930, PMID:28694258]."},"prefetch_data":{"uniprot":{"accession":"Q86YW0","full_name":"1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase zeta-1","aliases":["Phosphoinositide phospholipase C-zeta-1","Phospholipase C-zeta-1","PLC-zeta-1","Testis-development protein NYD-SP27"],"length_aa":608,"mass_kda":70.4,"function":"The production of the second messenger molecules diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3) is mediated by activated phosphatidylinositol-specific phospholipase C enzymes. In vitro, hydrolyzes PtdIns(4,5)P2 in a Ca(2+)-dependent manner. Triggers intracellular Ca(2+) oscillations in oocytes solely during M phase and is involved in inducing oocyte activation and initiating embryonic development up to the blastocyst stage. Is therefore a strong candidate for the egg-activating soluble sperm factor that is transferred from the sperm into the egg cytoplasm following gamete membrane fusion. May exert an inhibitory effect on phospholipase-C-coupled processes that depend on calcium ions and protein kinase C, including CFTR trafficking and function","subcellular_location":"Nucleus; Cytoplasm, perinuclear region","url":"https://www.uniprot.org/uniprotkb/Q86YW0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PLCZ1","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/PLCZ1","total_profiled":1310},"omim":[{"mim_id":"620500","title":"SPERMATOGENIC FAILURE 87; SPGF87","url":"https://www.omim.org/entry/620500"},{"mim_id":"620499","title":"SPERMATOGENIC FAILURE 86; SPGF86","url":"https://www.omim.org/entry/620499"},{"mim_id":"620353","title":"SPERMATOGENIC FAILURE 82; SPGF82","url":"https://www.omim.org/entry/620353"},{"mim_id":"620170","title":"SPERMATOGENIC FAILURE 78; SPGF78","url":"https://www.omim.org/entry/620170"},{"mim_id":"620160","title":"IQ MOTIF-CONTAINING PROTEIN N; IQCN","url":"https://www.omim.org/entry/620160"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"testis","ntpm":39.9}],"url":"https://www.proteinatlas.org/search/PLCZ1"},"hgnc":{"alias_symbol":["NYD-SP27","PLCzeta","Czeta"],"prev_symbol":[]},"alphafold":{"accession":"Q86YW0","domains":[{"cath_id":"1.10.238.10","chopping":"1-68","consensus_level":"medium","plddt":91.1578,"start":1,"end":68},{"cath_id":"1.10.238.10","chopping":"82-143","consensus_level":"high","plddt":92.6873,"start":82,"end":143},{"cath_id":"3.20.20.190","chopping":"160-315_340-463","consensus_level":"medium","plddt":94.3614,"start":160,"end":463},{"cath_id":"2.60.40.150","chopping":"481-606","consensus_level":"high","plddt":93.1433,"start":481,"end":606}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q86YW0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q86YW0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q86YW0-F1-predicted_aligned_error_v6.png","plddt_mean":92.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PLCZ1","jax_strain_url":"https://www.jax.org/strain/search?query=PLCZ1"},"sequence":{"accession":"Q86YW0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q86YW0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q86YW0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q86YW0"}},"corpus_meta":[{"pmid":"9374484","id":"PMC_9374484","title":"Protein kinase C-zeta as a downstream effector of phosphatidylinositol 3-kinase during insulin stimulation in rat adipocytes. Potential role in glucose transport.","date":"1997","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9374484","citation_count":402,"is_preprint":false},{"pmid":"1537859","id":"PMC_1537859","title":"Effect of phorbol esters on protein kinase C-zeta.","date":"1992","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/1537859","citation_count":302,"is_preprint":false},{"pmid":"12761192","id":"PMC_12761192","title":"Protein kinase Czeta (PKCzeta): activation mechanisms and cellular functions.","date":"2003","source":"Journal of biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12761192","citation_count":257,"is_preprint":false},{"pmid":"19584136","id":"PMC_19584136","title":"Reduced amounts and abnormal forms of phospholipase C zeta (PLCzeta) in spermatozoa from infertile men.","date":"2009","source":"Human reproduction (Oxford, England)","url":"https://pubmed.ncbi.nlm.nih.gov/19584136","citation_count":229,"is_preprint":false},{"pmid":"12416999","id":"PMC_12416999","title":"Sperm phospholipase Czeta from humans and cynomolgus monkeys triggers Ca2+ oscillations, activation and development of mouse oocytes.","date":"2002","source":"Reproduction (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/12416999","citation_count":228,"is_preprint":false},{"pmid":"15193147","id":"PMC_15193147","title":"Intracellular ceramide synthesis and protein kinase Czeta activation play an essential role in palmitate-induced insulin resistance in rat L6 skeletal muscle cells.","date":"2004","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/15193147","citation_count":219,"is_preprint":false},{"pmid":"11574404","id":"PMC_11574404","title":"Protein kinase Czeta activation mediates glucagon-like peptide-1-induced pancreatic beta-cell 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intracellular Ca²⁺ oscillations indistinguishable from those at fertilization by hydrolyzing PIP2 and generating InsP3, thereby initiating egg activation and embryo development.\",\n      \"method\": \"cRNA microinjection into mouse oocytes; Ca²⁺ imaging; identification of novel sperm-specific PLC isoform\",\n      \"journal\": \"Reproduction (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — replicated across multiple labs and species with cRNA injection, Ca²⁺ imaging, and recombinant protein assays\",\n      \"pmids\": [\"12416999\", \"15047934\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Recombinant PLCζ protein has an exceptionally high Ca²⁺ sensitivity (EC50 ~52 nM) for PIP2-hydrolyzing activity in vitro, approximately 100-fold higher than PLCδ1 (EC50 ~5.7 µM), enabling it to be active at resting intracellular Ca²⁺ levels (~100 nM).\",\n      \"method\": \"In vitro PIP2 hydrolysis assay at varying Ca²⁺ concentrations using baculovirus-expressed recombinant PLCζ; microinjection into mouse eggs\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro enzymatic reconstitution with purified recombinant protein, replicated by other labs\",\n      \"pmids\": [\"14701816\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"PLCζ-induced Ca²⁺ oscillations occur exclusively during M phase and are regulated by nuclear sequestration: PLCζ localizes to pronuclei via a nuclear localization signal (NLS), and sequestration into the pronucleus terminates Ca²⁺ oscillations at the interphase of the first cell cycle.\",\n      \"method\": \"Live-cell imaging of fluorescently tagged PLCζ; NLS mutagenesis; inhibition of pronuclear formation\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct localization experiments with functional consequence, NLS mutagenesis, multiple orthogonal approaches\",\n      \"pmids\": [\"15159452\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The EF-hand domains and C2 domain of PLCζ are essential for its enzymatic activity: deletion of the four EF-hand domains or the C2 domain abolishes PIP2-hydrolyzing activity. EF3 is responsible for high Ca²⁺ sensitivity, and the C2 domain has affinity for PI(3)P and PI(5)P, which negatively regulate PLCζ activity.\",\n      \"method\": \"Structure-function analysis via deletion mutagenesis; in vitro PIP2 hydrolysis assay; microinjection of mutant RNA into mouse eggs\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro enzymatic assay combined with domain deletion mutagenesis and in vivo Ca²⁺ oscillation assay\",\n      \"pmids\": [\"15790568\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"The X/Y linker region of PLCζ contains a nuclear localization signal (NLS) at residues 374-381 critical for pronuclear translocation; unlike somatic PLCs, the PLCζ X/Y linker does not mediate auto-inhibition but is required for catalytic activity.\",\n      \"method\": \"Point mutagenesis of NLS residues; fluorescent protein tagging; cRNA injection into mouse eggs; COS-7 cell transfection\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — mutagenesis with functional readouts in eggs and somatic cells, orthogonal methods\",\n      \"pmids\": [\"16854985\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Unlike somatic PLC isoforms that hydrolyze plasma membrane PI(4,5)P2, PLCζ targets an intracellular pool of PI(4,5)P2 present on cortical vesicles inside the egg to generate InsP3 and trigger Ca²⁺ oscillations.\",\n      \"method\": \"GFP-tagged PH domain to monitor plasma membrane PI(4,5)P2; targeted depletion of plasma membrane vs. intracellular PI(4,5)P2 by Inp54p phosphatase; immunolocalization of PLCζ and PI(4,5)P2; catalytically inactive PLCζ co-localization\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal approaches showing PLCζ targets intracellular PI(4,5)P2 vesicles, confirmed by gain- and loss-of-function experiments\",\n      \"pmids\": [\"22114355\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The PLCζ X/Y-linker region, unlike in somatic PLCs where it causes auto-inhibition, is required for PLCζ enzymatic activity; deletion of the XY-linker significantly diminishes in vitro PIP2 hydrolysis and in vivo Ca²⁺-oscillation-inducing activity.\",\n      \"method\": \"In vitro PIP2 hydrolysis assay; cRNA injection into mouse eggs; deletion mutagenesis of XY-linker\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro enzymatic reconstitution with mutagenesis and in vivo functional validation\",\n      \"pmids\": [\"21767260\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Transgenic RNAi knockdown of PLCζ in mouse sperm causes premature termination of Ca²⁺ oscillations after fertilization, reduced egg activation rates, and subfertility in vivo, demonstrating PLCζ is required for physiological Ca²⁺ oscillations.\",\n      \"method\": \"Transgenic shRNA expression in mice; in vitro fertilization with Ca²⁺ imaging; mating studies\",\n      \"journal\": \"Biology of reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic loss-of-function in vivo with defined molecular phenotype, later confirmed by full knockout\",\n      \"pmids\": [\"15601914\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"PLCζ knockout (Plcz1⁻/⁻) mouse sperm completely fail to trigger Ca²⁺ oscillations in eggs and cause polyspermy, demonstrating PLCζ is the physiological trigger of Ca²⁺ oscillations at fertilization; Plcz1⁻/⁻ males are subfertile but not sterile, indicating an alternative route to egg activation exists.\",\n      \"method\": \"Gene knockout mice (Plcz1⁻/⁻); Ca²⁺ imaging after in vitro fertilization; in vivo mating studies\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — definitive genetic knockout with specific molecular phenotype (loss of Ca²⁺ oscillations), replicated by accompanying studies\",\n      \"pmids\": [\"28694258\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"PLCζ remains functionally active after proteolytic cleavage at its X/Y linker region; N-terminal and C-terminal fragments remain associated as functional complexes capable of inducing Ca²⁺ oscillations and embryo development.\",\n      \"method\": \"In vitro protease (V8) cleavage of PLCζ; immunodepletion; co-expression of cRNAs encoding PLCζ N- and C-terminal fragments in mouse eggs; PLC activity assay\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro cleavage assay combined with in vivo co-expression reconstitution and immunodepletion\",\n      \"pmids\": [\"18028898\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"A point mutation in the catalytic region of human PLCζ (identified in an infertile patient) abolishes the ability of the protein to induce Ca²⁺ oscillations when microinjected into mouse oocytes, linking loss-of-function PLCζ mutations to male infertility.\",\n      \"method\": \"DNA sequencing; cRNA microinjection into mouse oocytes; Ca²⁺ imaging; immunofluorescence; sperm injection into mouse oocytes\",\n      \"journal\": \"Human reproduction (Oxford, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — functional validation of human mutation by mouse oocyte Ca²⁺ assay, corroborated by multiple subsequent studies\",\n      \"pmids\": [\"19584136\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"A homozygous missense mutation in PLCZ1 (c.1465A>T; p.Ile489Phe) in the C2 domain causes absence of PLCζ protein in sperm, mislocalization of the protein when expressed in oocytes, and highly abnormal Ca²⁺ transients, preventing oocyte activation. This identifies the C2 domain as required for proper PLCζ targeting and function.\",\n      \"method\": \"Whole-exome sequencing; western blotting; immunofluorescence; microinjection into mouse GV and MII oocytes; Ca²⁺ imaging\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — human disease mutation functionally validated with multiple orthogonal assays\",\n      \"pmids\": [\"26721930\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PLCζ/PLCδ1 chimera analysis demonstrates that the XY-linker and C2 domain of PLCζ are essential for Ca²⁺ oscillation-inducing activity in eggs; the XY-linker mediates binding to PIP2-containing liposomes, and the C2 domain mediates binding to PI(3)P-containing liposomes.\",\n      \"method\": \"Domain chimera construction; Ca²⁺ imaging in mouse eggs; in vitro PIP2 hydrolysis assay; liposome-binding assay; mathematical modeling\",\n      \"journal\": \"Molecular human reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro biochemical assays combined with in vivo functional readout and domain-swap mutagenesis\",\n      \"pmids\": [\"24152875\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"A male infertility-linked point mutation in human PLCζ introduced into mouse PLCζ completely abolishes in vitro PIP2 hydrolysis activity and in vivo Ca²⁺ oscillation-inducing ability; wild-type PLCζ initiates normal Ca²⁺ oscillations even in the presence of 10-fold excess mutant, ruling out a dominant-negative mechanism.\",\n      \"method\": \"In vitro PIP2 hydrolysis assay; cRNA microinjection into mouse eggs; Ca²⁺ imaging\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro enzymatic assay and in vivo functional validation of human disease mutation\",\n      \"pmids\": [\"21204786\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"PLCζ localizes along the inner acrosomal membrane and in the perinuclear theca (equatorial region) of normal human sperm; PLCζ is absent or greatly reduced in DPY19L2-deficient globozoospermic sperm (which lack acrosome and perinuclear theca), explaining failed Ca²⁺ oscillations and oocyte activation failure.\",\n      \"method\": \"Immunofluorescence localization in human and mouse sperm; Ca²⁺ imaging after ICSI with Dpy19l2 KO mouse sperm; western blotting\",\n      \"journal\": \"Molecular human reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct subcellular localization with functional consequence in defined KO model\",\n      \"pmids\": [\"25354701\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Ca²⁺ oscillation-inducing activity and nuclear translocation ability differ significantly among PLCζ orthologs from mouse, rat, human, and medaka fish; mouse PLCZ1 enters pronuclei in mouse eggs while rat and human PLCZ1 show defective nuclear translocation in mouse eggs, demonstrating species-specific NLS function.\",\n      \"method\": \"cRNA injection of PLCZ1 orthologs into mouse and rat eggs; Ca²⁺ imaging; fluorescence nuclear localization assay; RT-PCR\",\n      \"journal\": \"Biology of reproduction\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — orthogonal assays but single lab comparing species orthologs\",\n      \"pmids\": [\"18322275\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Recombinant wild-type human PLCζ protein, when microinjected into mouse oocytes, triggers characteristic Ca²⁺ oscillations and supports embryo development to the blastocyst stage; infertility-linked mutant forms of PLCζ display aberrant enzymatic activity and fail to activate oocytes, demonstrating PLCζ as a potential therapeutic agent.\",\n      \"method\": \"Recombinant protein expression in HEK293T cells; microinjection into mouse/human oocytes; Ca²⁺ imaging; in vitro PIP2 hydrolysis assay\",\n      \"journal\": \"Fertility and sterility\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — recombinant protein with enzymatic and in vivo functional validation\",\n      \"pmids\": [\"22999959\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PLCZ1 (PLCζ) is a sperm-specific phospholipase C that lacks a PH domain, is delivered into the egg cytoplasm upon gamete fusion, and catalyzes hydrolysis of PI(4,5)P2 on intracellular vesicles (not the plasma membrane) at nanomolar Ca²⁺ concentrations (EC50 ~52 nM) to generate InsP3, thereby triggering repetitive Ca²⁺ oscillations via the IP3 receptor pathway that initiate egg activation and embryogenesis; its activity depends on intact EF-hand (EF3 for Ca²⁺ sensitivity), XY-linker (required for catalysis and PIP2 binding), and C2 (required for activity and intracellular targeting) domains, and Ca²⁺ oscillations are terminated by PLCζ sequestration into the pronucleus via an NLS in the XY-linker region.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"PLCZ1 encodes a sperm-specific phospholipase C (PLCζ) that serves as the physiological trigger of egg activation at fertilization by generating repetitive intracellular Ca²⁺ oscillations essential for embryogenesis. Upon delivery into the egg cytoplasm at gamete fusion, PLCζ hydrolyzes an intracellular pool of PI(4,5)P₂ on cortical vesicles—rather than plasma membrane PIP₂—to produce InsP₃, which releases Ca²⁺ via IP₃ receptors; its exceptionally high Ca²⁺ sensitivity (EC₅₀ ~52 nM) enables activity at resting cytoplasmic Ca²⁺ levels [PMID:14701816, PMID:22114355]. Enzymatic function requires intact EF-hand domains (EF3 for Ca²⁺ sensitivity), an XY-linker region that uniquely promotes rather than auto-inhibits catalysis, and a C2 domain necessary for intracellular targeting and activity; Ca²⁺ oscillations are terminated when PLCζ translocates into the pronucleus via an NLS within the XY-linker [PMID:15790568, PMID:16854985, PMID:15159452]. Loss-of-function mutations in human PLCZ1 cause oocyte activation failure and male infertility, as demonstrated by patient mutation studies and confirmed by Plcz1-knockout mice that completely lack fertilization-triggered Ca²⁺ oscillations [PMID:19584136, PMID:26721930, PMID:28694258].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Identification of PLCζ as a novel sperm-specific phospholipase C resolved the long-standing question of the molecular identity of the sperm factor that triggers Ca²⁺ oscillations at fertilization.\",\n      \"evidence\": \"cRNA microinjection of newly cloned PLCZ1 into mouse oocytes recapitulated fertilization-like Ca²⁺ oscillations and egg activation\",\n      \"pmids\": [\"12416999\", \"15047934\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of PLCζ delivery from sperm to egg cytoplasm not defined\", \"Whether PLCζ is the sole sperm-derived oocyte-activating factor remained unknown\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Demonstration that PLCζ has ~100-fold higher Ca²⁺ sensitivity than PLCδ1 explained how it can function at resting intracellular Ca²⁺ concentrations without requiring receptor-mediated activation.\",\n      \"evidence\": \"In vitro PIP₂ hydrolysis assay with baculovirus-expressed recombinant PLCζ showed EC₅₀ ~52 nM vs ~5.7 µM for PLCδ1\",\n      \"pmids\": [\"14701816\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for high Ca²⁺ sensitivity not resolved\", \"Whether post-translational modifications modulate sensitivity in vivo unknown\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Structure–function studies of PLCζ domains and the discovery of nuclear sequestration established how Ca²⁺ oscillations are both generated and terminated during the first cell cycle: EF-hand and C2 domains are essential for catalysis, while an NLS in the XY-linker drives pronuclear translocation that stops oscillations.\",\n      \"evidence\": \"Deletion mutagenesis with in vitro PIP₂ hydrolysis and oocyte Ca²⁺ imaging; live-cell tracking of fluorescently tagged PLCζ with NLS mutations\",\n      \"pmids\": [\"15790568\", \"15159452\", \"16854985\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Crystal structure of PLCζ not available\", \"Mechanism by which C2 domain targets PLCζ to intracellular membranes not fully resolved\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Transgenic RNAi knockdown of PLCζ in mouse sperm provided loss-of-function evidence that endogenous PLCζ is required for sustained Ca²⁺ oscillations and normal fertility in vivo.\",\n      \"evidence\": \"Transgenic shRNA in mice; IVF with Ca²⁺ imaging; mating studies showing subfertility\",\n      \"pmids\": [\"15601914\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Knockdown was incomplete, leaving open whether PLCζ is absolutely required\", \"Residual fertility suggested alternative activation pathways\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Identification and functional validation of a catalytic-domain mutation in an infertile patient established PLCζ loss-of-function as a cause of human male infertility due to oocyte activation failure.\",\n      \"evidence\": \"Sequencing of infertile patient; mutant cRNA microinjection into mouse oocytes abolished Ca²⁺ oscillations\",\n      \"pmids\": [\"19584136\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Number of patients studied was small\", \"Genetic background and additional mutations not fully excluded\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Discovery that PLCζ targets intracellular vesicular PI(4,5)P₂ rather than plasma membrane PIP₂ resolved why PLCζ lacks a PH domain and explained its unique mechanism among PLC isoforms.\",\n      \"evidence\": \"GFP-PH domain reporters, targeted PI(4,5)P₂ depletion by Inp54p phosphatase, immunolocalization of PLCζ on cortical vesicles\",\n      \"pmids\": [\"22114355\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity and biogenesis of the intracellular PIP₂-containing vesicles not characterized\", \"Whether PLCζ also acts on other phosphoinositide pools in vivo unknown\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Functional validation of a human infertility mutation in mouse PLCζ confirmed that loss of enzymatic activity is the disease mechanism and ruled out dominant-negative effects, clarifying the recessive inheritance pattern.\",\n      \"evidence\": \"In vitro PIP₂ hydrolysis assay and cRNA co-injection of wild-type and 10-fold excess mutant PLCζ into mouse oocytes\",\n      \"pmids\": [\"21204786\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Limited to one mutation; generalizability to other PLCZ1 variants not tested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Domain chimera analysis between PLCζ and PLCδ1 pinpointed the XY-linker as a PIP₂-binding module and the C2 domain as a PI(3)P-binding module, together conferring PLCζ's unique intracellular targeting and catalytic properties.\",\n      \"evidence\": \"PLCζ/PLCδ1 chimeras tested with liposome-binding assays, in vitro PIP₂ hydrolysis, and oocyte Ca²⁺ imaging\",\n      \"pmids\": [\"24152875\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for XY-linker PIP₂ interaction not determined\", \"Whether PI(3)P binding inhibits or redirects PLCζ in intact eggs unclear\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"A homozygous C2-domain mutation (p.Ile489Phe) causing protein absence in sperm and mislocalization in oocytes proved the C2 domain is essential for PLCζ stability, targeting, and oocyte activation in humans.\",\n      \"evidence\": \"Whole-exome sequencing of infertile patient; western blot; immunofluorescence; cRNA injection into mouse oocytes with Ca²⁺ imaging\",\n      \"pmids\": [\"26721930\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the mutation destabilizes PLCζ globally or specifically disrupts C2-membrane interaction not distinguished\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Complete genetic knockout of Plcz1 definitively established PLCζ as the physiological Ca²⁺ oscillation trigger at fertilization while revealing an alternative, PLCζ-independent route to egg activation that permits residual fertility.\",\n      \"evidence\": \"Plcz1⁻/⁻ knockout mice; IVF with Ca²⁺ imaging showing total loss of oscillations; in vivo mating showing subfertility but not sterility\",\n      \"pmids\": [\"28694258\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the alternative egg activation mechanism is unknown\", \"Whether compensatory mechanisms are upregulated in knockout animals not tested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The structural basis for PLCζ's uniquely high Ca²⁺ sensitivity, the identity of the intracellular PIP₂-containing vesicles it targets, and the mechanism of the alternative PLCζ-independent egg activation pathway remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No crystal or cryo-EM structure of PLCζ available\", \"Molecular identity of intracellular PIP₂ vesicle compartment not defined\", \"PLCζ-independent egg activation factor not identified\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 1, 3, 6, 12, 13]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [5, 12]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [2, 4, 15]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0, 5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1, 5]},\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [0, 7, 8]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"DPY19L2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}