{"gene":"MYOZ1","run_date":"2026-06-10T05:19:52","timeline":{"discoveries":[{"year":2000,"finding":"FATZ (MYOZ1) is a 32-kDa Z-disc protein that binds to alpha-actinin-2 (via its SR3-SR4 domains interacting with the COOH-terminal region of FATZ), gamma-filamin/ABP-L, and telethonin, identifying it as a multivalent scaffold within the Z-disc protein network. Alpha-actinin-2 SR3-SR4 domains are required for binding the C-terminal region of FATZ.","method":"Yeast two-hybrid, GST overlay assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid and GST overlay assay from a single lab, two orthogonal methods identifying binding partners and required domains","pmids":["10984498"],"is_preprint":false},{"year":2005,"finding":"FATZ-1 (MYOZ1) interacts with myotilin via its C-terminal region; N- or C-terminal truncations of myotilin abrogate this binding. FATZ-1 also binds to filamin-C (Ig repeats 19-24) as well as filamin-A and filamin-B via sequences within either its N- or C-terminal region, providing a molecular link between Z-disc proteins and the sarcolemma through filamins and beta1 integrins.","method":"Transfection, biochemical pulldown, yeast two-hybrid assay","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal binding shown by multiple methods (transfection, biochemical, Y2H), single lab, orthogonal approaches","pmids":["16076904"],"is_preprint":false},{"year":2008,"finding":"FATZ-1 (MYOZ1) harbors a conserved C-terminal class III PDZ binding motif (E[ST][DE][DE]L) shared with the myotilin family that mediates interaction with PDZ domains of Enigma family members ZASP/Cypher, ALP, CLP-36, and RIL. PKA phosphorylates the C-terminus of FATZ-1, which modulates this interaction. CaMKII phosphorylates FATZ-3 and myotilin at the same motif.","method":"In vitro binding assays, in vivo co-immunoprecipitation, phosphorylation assays","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro and in vivo binding plus phosphorylation assays, single lab, multiple orthogonal methods","pmids":["19047374"],"is_preprint":false},{"year":2021,"finding":"FATZ-1 (MYOZ1) forms a tight fuzzy complex with alpha-actinin-2 via main molecular recognition elements and secondary binding sites, with an interaction mechanism resolved as a conformational ensemble. The complex has a polar architecture that may organize interaction partners and stabilize alpha-actinin-2 orientation in the Z-disc. Additionally, FATZ-1 can phase-separate and form biomolecular condensates with alpha-actinin-2, suggesting a role in creating an interaction hub for Z-disc proteins through membraneless compartmentalization during myofibrillogenesis.","method":"Integrative structural biology (SAXS, NMR, cryo-EM), cellular validation, phase-separation assays","journal":"Science advances","confidence":"High","confidence_rationale":"Tier 1 / Strong — first structural determination of the complex with multiple orthogonal biophysical methods (SAXS, NMR, cryo-EM) plus cellular validation and phase-separation assays in a single rigorous study","pmids":["34049882"],"is_preprint":false},{"year":2022,"finding":"MYOZ1 is ubiquitinated by the circadian E3 ligase FBXL21 (identified by yeast two-hybrid as an FBXL21-binding protein), leading to proteasomal degradation. GSK-3β co-expression accelerates and GSK-3β inhibition decelerates FBXL21-mediated MYOZ1 degradation. MYOZ1 degradation regulates calcineurin/NFAT signaling: MYOZ1 inhibits calcineurin/NFAT; FBXL21 KO results in MYOZ1 accumulation, impaired NFAT nuclear localization, reduced NFAT target gene expression, impaired myoblast differentiation, and disrupted sarcomere structure.","method":"Yeast two-hybrid (binding identification), co-immunoprecipitation, ubiquitination assay, GSK-3β pharmacological inhibition/overexpression, C2C12 KO cell lines, NFAT localization imaging, Psttm mouse model","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (Y2H, Co-IP, ubiquitination assay, KO cell lines, mouse model) across both in vitro and in vivo, identifying writer (FBXL21), co-regulator (GSK-3β), and downstream pathway (calcineurin/NFAT)","pmids":["36574402"],"is_preprint":false}],"current_model":"MYOZ1 (FATZ) is a Z-disc scaffold protein that forms a fuzzy but tight complex with alpha-actinin-2, binds filamin isoforms, telethonin, myotilin, and Enigma family members (via a conserved C-terminal PDZ-binding motif phosphorylatable by PKA), and is subject to FBXL21-mediated ubiquitination and proteasomal degradation (potentiated by GSK-3β), whereby its regulated degradation controls calcineurin/NFAT signaling, myoblast differentiation, and sarcomere structural integrity; additionally, FATZ-1 can phase-separate with alpha-actinin-2, suggesting it may organize Z-disc protein interactions through membraneless condensates."},"narrative":{"mechanistic_narrative":"MYOZ1 (FATZ) is a multivalent Z-disc scaffold protein that organizes the sarcomeric protein network and regulates calcium signaling during muscle differentiation and structural maintenance [PMID:10984498, PMID:36574402]. It binds alpha-actinin-2 through its C-terminal region and integrates additional Z-disc components including gamma-filamin/ABP-L, telethonin, myotilin, and the filamin-C, -A, and -B isoforms, the latter linking the Z-disc to the sarcolemma via filamins and beta1 integrins [PMID:10984498, PMID:16076904]. A conserved C-terminal class III PDZ-binding motif (E[ST][DE][DE]L) mediates interaction with the PDZ domains of Enigma-family proteins ZASP/Cypher, ALP, CLP-36, and RIL, and PKA phosphorylation of this C-terminus modulates these contacts [PMID:19047374]. Structurally, MYOZ1 forms a tight fuzzy complex with alpha-actinin-2 as a conformational ensemble with a polar architecture that stabilizes alpha-actinin-2 orientation, and it can phase-separate with alpha-actinin-2 to form biomolecular condensates, providing a membraneless interaction hub during myofibrillogenesis [PMID:34049882]. MYOZ1 abundance is controlled by the circadian E3 ligase FBXL21, which ubiquitinates it for proteasomal degradation in a manner accelerated by GSK-3beta; through this regulated turnover MYOZ1 inhibits calcineurin/NFAT signaling, and its accumulation upon FBXL21 loss impairs NFAT nuclear localization, NFAT target gene expression, myoblast differentiation, and sarcomere integrity [PMID:36574402].","teleology":[{"year":2000,"claim":"Establishing MYOZ1 as a Z-disc protein, the founding question was what it binds; demonstrating direct interactions with alpha-actinin-2, gamma-filamin, and telethonin defined it as a multivalent scaffold within the Z-disc network.","evidence":"Yeast two-hybrid and GST overlay assays mapping the alpha-actinin-2 SR3-SR4 / FATZ C-terminus interaction","pmids":["10984498"],"confidence":"Medium","gaps":["Binding shown in vitro and by Y2H without endogenous reconstitution","Functional consequence of each interaction in muscle not addressed","Stoichiometry and structural basis of binding unresolved"]},{"year":2005,"claim":"Extending the interactome, the question was how MYOZ1 connects the Z-disc to the cell periphery; binding to myotilin and to filamin-A/-B/-C established a molecular link from Z-disc proteins to the sarcolemma through filamins and beta1 integrins.","evidence":"Transfection, biochemical pulldown, and yeast two-hybrid mapping of myotilin and filamin binding regions","pmids":["16076904"],"confidence":"Medium","gaps":["Whether N- or C-terminal filamin binding occurs simultaneously not resolved","Physiological role of the sarcolemmal link not tested in vivo"]},{"year":2008,"claim":"Asking how MYOZ1 interactions are encoded and regulated, identification of a conserved C-terminal class III PDZ-binding motif binding Enigma-family PDZ proteins, plus PKA phosphorylation of this motif, revealed a phospho-regulated docking site shared across the myotilin family.","evidence":"In vitro binding, in vivo co-immunoprecipitation, and phosphorylation assays","pmids":["19047374"],"confidence":"Medium","gaps":["Functional effect of PKA phosphorylation on Z-disc assembly in vivo not established","Kinase signaling upstream of this motif not defined for MYOZ1 specifically"]},{"year":2021,"claim":"Moving from binary interactions to mechanism, the question was how MYOZ1 physically organizes the Z-disc; structural resolution of a tight fuzzy complex with alpha-actinin-2 and demonstration of phase separation established that MYOZ1 builds a polar, condensate-forming interaction hub.","evidence":"Integrative structural biology (SAXS, NMR, cryo-EM) with cellular validation and phase-separation assays","pmids":["34049882"],"confidence":"High","gaps":["In vivo relevance of condensate formation during myofibrillogenesis not directly demonstrated","How other partners are recruited into the condensate not resolved"]},{"year":2022,"claim":"Addressing how MYOZ1 levels are controlled and what they signal, FBXL21-mediated ubiquitination with GSK-3beta as a co-regulator linked MYOZ1 turnover to calcineurin/NFAT signaling, myoblast differentiation, and sarcomere integrity.","evidence":"Yeast two-hybrid, Co-IP, ubiquitination assay, GSK-3beta modulation, C2C12 KO lines, NFAT imaging, and Psttm mouse model","pmids":["36574402"],"confidence":"High","gaps":["Phosphodegron site on MYOZ1 targeted by GSK-3beta not mapped","Mechanism by which MYOZ1 inhibits calcineurin/NFAT not defined at the molecular level"]},{"year":null,"claim":"How the scaffolding, phase-separation, and degradation functions of MYOZ1 are integrated to control sarcomere assembly versus calcium signaling in intact muscle over time remains open.","evidence":"","pmids":[],"confidence":"High","gaps":["No direct test linking condensate formation to NFAT regulation","Tissue- and fiber-type-specific roles of MYOZ1 turnover not resolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0,1,3]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1,2]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[0,1]}],"pathway":[{"term_id":"R-HSA-397014","term_label":"Muscle contraction","supporting_discovery_ids":[0,4]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[4]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[4]}],"complexes":["Z-disc"],"partners":["ACTN2","FLNC","FLNA","FLNB","TCAP","MYOT","FBXL21","GSK3B"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9NP98","full_name":"Myozenin-1","aliases":["Calsarcin-2","Filamin-, actinin- and telethonin-binding protein","Protein FATZ"],"length_aa":299,"mass_kda":31.7,"function":"Myozenins may serve as intracellular binding proteins involved in linking Z-disk proteins such as alpha-actinin, gamma-filamin, TCAP/telethonin, LDB3/ZASP and localizing calcineurin signaling to the sarcomere. Plays an important role in the modulation of calcineurin signaling. May play a role in myofibrillogenesis","subcellular_location":"Nucleus; Cell projection, pseudopodium","url":"https://www.uniprot.org/uniprotkb/Q9NP98/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MYOZ1","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MYOZ1","total_profiled":1310},"omim":[{"mim_id":"610735","title":"MYOZENIN 3; MYOZ3","url":"https://www.omim.org/entry/610735"},{"mim_id":"605906","title":"LIM DOMAIN-BINDING 3; LDB3","url":"https://www.omim.org/entry/605906"},{"mim_id":"605603","title":"MYOZENIN 1; MYOZ1","url":"https://www.omim.org/entry/605603"},{"mim_id":"605602","title":"MYOZENIN 2; MYOZ2","url":"https://www.omim.org/entry/605602"},{"mim_id":"602228","title":"TRANSCRIPTION FACTOR 7-LIKE 2; TCF7L2","url":"https://www.omim.org/entry/602228"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"skeletal muscle","ntpm":6684.6},{"tissue":"tongue","ntpm":3089.0}],"url":"https://www.proteinatlas.org/search/MYOZ1"},"hgnc":{"alias_symbol":["FATZ","CS-2"],"prev_symbol":["MYOZ"]},"alphafold":{"accession":"Q9NP98","domains":[{"cath_id":"-","chopping":"44-80","consensus_level":"medium","plddt":80.8443,"start":44,"end":80}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NP98","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NP98-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NP98-F1-predicted_aligned_error_v6.png","plddt_mean":57.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MYOZ1","jax_strain_url":"https://www.jax.org/strain/search?query=MYOZ1"},"sequence":{"accession":"Q9NP98","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9NP98.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9NP98/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NP98"}},"corpus_meta":[{"pmid":"10984498","id":"PMC_10984498","title":"FATZ, a filamin-, actinin-, and telethonin-binding protein of the Z-disc of skeletal muscle.","date":"2000","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10984498","citation_count":133,"is_preprint":false},{"pmid":"16076904","id":"PMC_16076904","title":"The Z-disc proteins myotilin and FATZ-1 interact with each other and are connected to the sarcolemma via muscle-specific filamins.","date":"2005","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/16076904","citation_count":110,"is_preprint":false},{"pmid":"19047374","id":"PMC_19047374","title":"A class III PDZ binding motif in the myotilin and FATZ families binds enigma family proteins: a common link for Z-disc myopathies.","date":"2008","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/19047374","citation_count":84,"is_preprint":false},{"pmid":"26073630","id":"PMC_26073630","title":"Genetic variants associated with risk of atrial fibrillation regulate expression of PITX2, CAV1, MYOZ1, C9orf3 and FANCC.","date":"2015","source":"Journal of molecular and cellular cardiology","url":"https://pubmed.ncbi.nlm.nih.gov/26073630","citation_count":38,"is_preprint":false},{"pmid":"17254821","id":"PMC_17254821","title":"Mutations in PDLIM3 and MYOZ1 encoding myocyte Z line proteins are infrequently found in idiopathic dilated cardiomyopathy.","date":"2007","source":"Molecular genetics and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/17254821","citation_count":30,"is_preprint":false},{"pmid":"34049882","id":"PMC_34049882","title":"Order from disorder in the sarcomere: FATZ forms a fuzzy but tight complex and phase-separated condensates with α-actinin.","date":"2021","source":"Science advances","url":"https://pubmed.ncbi.nlm.nih.gov/34049882","citation_count":19,"is_preprint":false},{"pmid":"36140742","id":"PMC_36140742","title":"MYOZ1 Gene Promotes Muscle Growth and Development in Meat Ducks.","date":"2022","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/36140742","citation_count":12,"is_preprint":false},{"pmid":"39408638","id":"PMC_39408638","title":"Transcriptomic Insights into the Atrial Fibrillation Susceptibility Locus near the MYOZ1 and SYNPO2L Genes.","date":"2024","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/39408638","citation_count":7,"is_preprint":false},{"pmid":"36574402","id":"PMC_36574402","title":"The circadian E3 ligase FBXL21 regulates myoblast differentiation and sarcomere architecture via MYOZ1 ubiquitination and NFAT signaling.","date":"2022","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/36574402","citation_count":5,"is_preprint":false},{"pmid":"36624802","id":"PMC_36624802","title":"The Expression of Myoz1 and ApoB is Positively Correlated with Meat Quality of Broiler Chicken.","date":"2022","source":"Veterinary medicine international","url":"https://pubmed.ncbi.nlm.nih.gov/36624802","citation_count":1,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7739,"output_tokens":1650,"usd":0.023984,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8426,"output_tokens":2503,"usd":0.052353,"stage2_stop_reason":"end_turn"},"total_usd":0.076337,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2000,\n      \"finding\": \"FATZ (MYOZ1) is a 32-kDa Z-disc protein that binds to alpha-actinin-2 (via its SR3-SR4 domains interacting with the COOH-terminal region of FATZ), gamma-filamin/ABP-L, and telethonin, identifying it as a multivalent scaffold within the Z-disc protein network. Alpha-actinin-2 SR3-SR4 domains are required for binding the C-terminal region of FATZ.\",\n      \"method\": \"Yeast two-hybrid, GST overlay assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid and GST overlay assay from a single lab, two orthogonal methods identifying binding partners and required domains\",\n      \"pmids\": [\"10984498\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"FATZ-1 (MYOZ1) interacts with myotilin via its C-terminal region; N- or C-terminal truncations of myotilin abrogate this binding. FATZ-1 also binds to filamin-C (Ig repeats 19-24) as well as filamin-A and filamin-B via sequences within either its N- or C-terminal region, providing a molecular link between Z-disc proteins and the sarcolemma through filamins and beta1 integrins.\",\n      \"method\": \"Transfection, biochemical pulldown, yeast two-hybrid assay\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal binding shown by multiple methods (transfection, biochemical, Y2H), single lab, orthogonal approaches\",\n      \"pmids\": [\"16076904\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"FATZ-1 (MYOZ1) harbors a conserved C-terminal class III PDZ binding motif (E[ST][DE][DE]L) shared with the myotilin family that mediates interaction with PDZ domains of Enigma family members ZASP/Cypher, ALP, CLP-36, and RIL. PKA phosphorylates the C-terminus of FATZ-1, which modulates this interaction. CaMKII phosphorylates FATZ-3 and myotilin at the same motif.\",\n      \"method\": \"In vitro binding assays, in vivo co-immunoprecipitation, phosphorylation assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro and in vivo binding plus phosphorylation assays, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"19047374\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"FATZ-1 (MYOZ1) forms a tight fuzzy complex with alpha-actinin-2 via main molecular recognition elements and secondary binding sites, with an interaction mechanism resolved as a conformational ensemble. The complex has a polar architecture that may organize interaction partners and stabilize alpha-actinin-2 orientation in the Z-disc. Additionally, FATZ-1 can phase-separate and form biomolecular condensates with alpha-actinin-2, suggesting a role in creating an interaction hub for Z-disc proteins through membraneless compartmentalization during myofibrillogenesis.\",\n      \"method\": \"Integrative structural biology (SAXS, NMR, cryo-EM), cellular validation, phase-separation assays\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — first structural determination of the complex with multiple orthogonal biophysical methods (SAXS, NMR, cryo-EM) plus cellular validation and phase-separation assays in a single rigorous study\",\n      \"pmids\": [\"34049882\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"MYOZ1 is ubiquitinated by the circadian E3 ligase FBXL21 (identified by yeast two-hybrid as an FBXL21-binding protein), leading to proteasomal degradation. GSK-3β co-expression accelerates and GSK-3β inhibition decelerates FBXL21-mediated MYOZ1 degradation. MYOZ1 degradation regulates calcineurin/NFAT signaling: MYOZ1 inhibits calcineurin/NFAT; FBXL21 KO results in MYOZ1 accumulation, impaired NFAT nuclear localization, reduced NFAT target gene expression, impaired myoblast differentiation, and disrupted sarcomere structure.\",\n      \"method\": \"Yeast two-hybrid (binding identification), co-immunoprecipitation, ubiquitination assay, GSK-3β pharmacological inhibition/overexpression, C2C12 KO cell lines, NFAT localization imaging, Psttm mouse model\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (Y2H, Co-IP, ubiquitination assay, KO cell lines, mouse model) across both in vitro and in vivo, identifying writer (FBXL21), co-regulator (GSK-3β), and downstream pathway (calcineurin/NFAT)\",\n      \"pmids\": [\"36574402\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MYOZ1 (FATZ) is a Z-disc scaffold protein that forms a fuzzy but tight complex with alpha-actinin-2, binds filamin isoforms, telethonin, myotilin, and Enigma family members (via a conserved C-terminal PDZ-binding motif phosphorylatable by PKA), and is subject to FBXL21-mediated ubiquitination and proteasomal degradation (potentiated by GSK-3β), whereby its regulated degradation controls calcineurin/NFAT signaling, myoblast differentiation, and sarcomere structural integrity; additionally, FATZ-1 can phase-separate with alpha-actinin-2, suggesting it may organize Z-disc protein interactions through membraneless condensates.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MYOZ1 (FATZ) is a multivalent Z-disc scaffold protein that organizes the sarcomeric protein network and regulates calcium signaling during muscle differentiation and structural maintenance [#0, #4]. It binds alpha-actinin-2 through its C-terminal region and integrates additional Z-disc components including gamma-filamin/ABP-L, telethonin, myotilin, and the filamin-C, -A, and -B isoforms, the latter linking the Z-disc to the sarcolemma via filamins and beta1 integrins [#0, #1]. A conserved C-terminal class III PDZ-binding motif (E[ST][DE][DE]L) mediates interaction with the PDZ domains of Enigma-family proteins ZASP/Cypher, ALP, CLP-36, and RIL, and PKA phosphorylation of this C-terminus modulates these contacts [#2]. Structurally, MYOZ1 forms a tight fuzzy complex with alpha-actinin-2 as a conformational ensemble with a polar architecture that stabilizes alpha-actinin-2 orientation, and it can phase-separate with alpha-actinin-2 to form biomolecular condensates, providing a membraneless interaction hub during myofibrillogenesis [#3]. MYOZ1 abundance is controlled by the circadian E3 ligase FBXL21, which ubiquitinates it for proteasomal degradation in a manner accelerated by GSK-3beta; through this regulated turnover MYOZ1 inhibits calcineurin/NFAT signaling, and its accumulation upon FBXL21 loss impairs NFAT nuclear localization, NFAT target gene expression, myoblast differentiation, and sarcomere integrity [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Establishing MYOZ1 as a Z-disc protein, the founding question was what it binds; demonstrating direct interactions with alpha-actinin-2, gamma-filamin, and telethonin defined it as a multivalent scaffold within the Z-disc network.\",\n      \"evidence\": \"Yeast two-hybrid and GST overlay assays mapping the alpha-actinin-2 SR3-SR4 / FATZ C-terminus interaction\",\n      \"pmids\": [\"10984498\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Binding shown in vitro and by Y2H without endogenous reconstitution\", \"Functional consequence of each interaction in muscle not addressed\", \"Stoichiometry and structural basis of binding unresolved\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Extending the interactome, the question was how MYOZ1 connects the Z-disc to the cell periphery; binding to myotilin and to filamin-A/-B/-C established a molecular link from Z-disc proteins to the sarcolemma through filamins and beta1 integrins.\",\n      \"evidence\": \"Transfection, biochemical pulldown, and yeast two-hybrid mapping of myotilin and filamin binding regions\",\n      \"pmids\": [\"16076904\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether N- or C-terminal filamin binding occurs simultaneously not resolved\", \"Physiological role of the sarcolemmal link not tested in vivo\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Asking how MYOZ1 interactions are encoded and regulated, identification of a conserved C-terminal class III PDZ-binding motif binding Enigma-family PDZ proteins, plus PKA phosphorylation of this motif, revealed a phospho-regulated docking site shared across the myotilin family.\",\n      \"evidence\": \"In vitro binding, in vivo co-immunoprecipitation, and phosphorylation assays\",\n      \"pmids\": [\"19047374\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional effect of PKA phosphorylation on Z-disc assembly in vivo not established\", \"Kinase signaling upstream of this motif not defined for MYOZ1 specifically\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Moving from binary interactions to mechanism, the question was how MYOZ1 physically organizes the Z-disc; structural resolution of a tight fuzzy complex with alpha-actinin-2 and demonstration of phase separation established that MYOZ1 builds a polar, condensate-forming interaction hub.\",\n      \"evidence\": \"Integrative structural biology (SAXS, NMR, cryo-EM) with cellular validation and phase-separation assays\",\n      \"pmids\": [\"34049882\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo relevance of condensate formation during myofibrillogenesis not directly demonstrated\", \"How other partners are recruited into the condensate not resolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Addressing how MYOZ1 levels are controlled and what they signal, FBXL21-mediated ubiquitination with GSK-3beta as a co-regulator linked MYOZ1 turnover to calcineurin/NFAT signaling, myoblast differentiation, and sarcomere integrity.\",\n      \"evidence\": \"Yeast two-hybrid, Co-IP, ubiquitination assay, GSK-3beta modulation, C2C12 KO lines, NFAT imaging, and Psttm mouse model\",\n      \"pmids\": [\"36574402\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Phosphodegron site on MYOZ1 targeted by GSK-3beta not mapped\", \"Mechanism by which MYOZ1 inhibits calcineurin/NFAT not defined at the molecular level\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the scaffolding, phase-separation, and degradation functions of MYOZ1 are integrated to control sarcomere assembly versus calcium signaling in intact muscle over time remains open.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No direct test linking condensate formation to NFAT regulation\", \"Tissue- and fiber-type-specific roles of MYOZ1 turnover not resolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0, 1, 3]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-397014\", \"supporting_discovery_ids\": [0, 4]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"complexes\": [\"Z-disc\"],\n    \"partners\": [\"ACTN2\", \"FLNC\", \"FLNA\", \"FLNB\", \"TCAP\", \"MYOT\", \"FBXL21\", \"GSK3B\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}