{"doi":"10.1073/pnas.86.16.6161","title":"Actin filaments mediate Dictyostelium myosin assembly in vitro.","abstract":"<jats:p>Because myosin thick filaments form in the actin-rich cortex of nonmuscle cells, we have examined the role of Dictyostelium actin filaments in the assembly of Dictyostelium myosin (type II). Fluorescence energy transfer and light-scattering assembly assays indicate that self-association of Dictyostelium myosin into bipolar thick filaments is kinetically regulated by actin filament networks. Regulation is nucleotide dependent but does not require ATP hydrolysis. Myosin assembly is accelerated approximately 5-fold by actin filaments when either 1 mM ATP or 1 mM adenosine 5'-[beta,gamma-imido]triphosphate (AMP-P[NH]P) is present. However, actin filaments together with 1 mM ADP abolish myosin assembly. Accelerated assembly appears to require transient binding of myosin molecules to actin filaments before incorporation into thick filaments. Fluorescence energy-transfer assays demonstrate that myosin associates with actin filaments at a rate that is equivalent to the accelerated myosin assembly rate, evidence that myosin to actin binding is a rate-limiting step in accelerated thick filament formation. Actin filament networks are also implicated in regulation of thick filament formation, since fragmentation of F-actin networks by severin causes immediate cessation of accelerated myosin assembly. Electron microscopic studies support a model of actin filament-mediated myosin assembly. In ADP, myosin monomers rapidly decorate F-actin, preventing extensive formation of thick filaments. In AMP-P[NH]P, myosin assembles along actin filaments, forming structures that resemble primitive stress fibers. Taken together, these data suggest a model in which site-directed assembly of thick filaments in Dictyostelium is mediated by the interaction of myosin monomers with cortical actin filament networks.</jats:p>","journal":"Proceedings of the National Academy of Sciences","year":1989,"id":623349,"datarank":0.5806801516361837,"base_score":3.8712010109078907,"endowment":3.8712010109078907,"self_citation_contribution":0.5806801516361837,"citation_network_contribution":0.0,"self_endowment_contribution":0.5806801516361837,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":47,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1610920,"name":"K T Vaughan","orcid":null,"position":1,"is_corresponding":false},{"id":1610921,"name":"J A Johns","orcid":null,"position":2,"is_corresponding":false},{"id":1610922,"name":"J D Pardee","orcid":null,"position":3,"is_corresponding":false},{"id":1610919,"name":"R K Mahajan","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"resolved":true,"title":"Actin filaments mediate Dictyostelium myosin assembly in vitro.","abstract":"<jats:p>Because myosin thick filaments form in the actin-rich cortex of nonmuscle cells, we have examined the role of Dictyostelium actin filaments in the assembly of Dictyostelium myosin (type II). Fluorescence energy transfer and light-scattering assembly assays indicate that self-association of Dictyostelium myosin into bipolar thick filaments is kinetically regulated by actin filament networks. Regulation is nucleotide dependent but does not require ATP hydrolysis. Myosin assembly is accelerated approximately 5-fold by actin filaments when either 1 mM ATP or 1 mM adenosine 5'-[beta,gamma-imido]triphosphate (AMP-P[NH]P) is present. However, actin filaments together with 1 mM ADP abolish myosin assembly. Accelerated assembly appears to require transient binding of myosin molecules to actin filaments before incorporation into thick filaments. Fluorescence energy-transfer assays demonstrate that myosin associates with actin filaments at a rate that is equivalent to the accelerated myosin assembly rate, evidence that myosin to actin binding is a rate-limiting step in accelerated thick filament formation. Actin filament networks are also implicated in regulation of thick filament formation, since fragmentation of F-actin networks by severin causes immediate cessation of accelerated myosin assembly. Electron microscopic studies support a model of actin filament-mediated myosin assembly. In ADP, myosin monomers rapidly decorate F-actin, preventing extensive formation of thick filaments. In AMP-P[NH]P, myosin assembles along actin filaments, forming structures that resemble primitive stress fibers. Taken together, these data suggest a model in which site-directed assembly of thick filaments in Dictyostelium is mediated by the interaction of myosin monomers with cortical actin filament networks.</jats:p>","is_dataset_classified":null,"base_score":3.8712010109078907,"endowment":3.8712010109078907,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"2762319","pmcid":"PMC297797","openalex_id":"https://openalex.org/W1999469923","authors":[],"funders":[{"funder_name":"NIADDK NIH HHS","grant_id":"AM 32147","title":null},{"funder_name":"NIGMS NIH HHS","grant_id":"GM 32458","title":null}],"total_grants":2,"fwci":1.6336,"citation_percentile":0.82616616,"influential_citations":0,"citation_trend":[{"year":2012,"count":3},{"year":2013,"count":3},{"year":2014,"count":2},{"year":2015,"count":3},{"year":2016,"count":1},{"year":2017,"count":1},{"year":2019,"count":3},{"year":2021,"count":1},{"year":2023,"count":2}],"oa_status":"green","license":null,"oa_locations":[{"url":"https://www.ncbi.nlm.nih.gov/pmc/articles/297797","host_type":"repository"},{"url":"https://www.ncbi.nlm.nih.gov/pmc/articles/297797","host_type":"repository"},{"url":"https://pnas.org/doi/pdf/10.1073/pnas.86.16.6161","host_type":"publisher"},{"url":"https://doi.org/10.1073/pnas.86.16.6161","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/2762319","host_type":"repository"}],"fields_of_study":["Cardiomyopathy and Myosin Studies","Cellular Mechanics and Interactions","Muscle activation and electromyography studies","Actins","Adenine Nucleotides","Dictyostelium","Fluorescent Dyes","Fungal Proteins","Kinetics","Light","Macromolecular Substances","Microfilament Proteins","Myosins","Protozoan Proteins","Scattering, Radiation","Spectrometry, Fluorescence"],"mesh_terms":["Actins","Adenine Nucleotides","Dictyostelium","Fluorescent Dyes","Fungal Proteins","Kinetics","Light","Microfilament Proteins","Myosins","Scattering, Radiation","Spectrometry, Fluorescence","Protozoan Proteins","Macromolecular Substances"],"keywords":["Myosin","Myosin head","Actin remodeling","Microfilament","Actin","Protein filament","Dictyostelium","Biophysics","Treadmilling","Cell biology","Biology","Meromyosin","Actin remodeling of neurons","Myosin light-chain kinase","Chemistry","Actin cytoskeleton","Cytoskeleton","Biochemistry","Cell"],"sdg_mappings":[{"sdg_number":0,"sdg_label":"Affordable and clean energy"}],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-08-03T23:24:21.019147Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}