{"doi":"10.17615/21a0-fb32","title":"Human Myosin Vc Is a Low Duty Ratio, Nonprocessive Molecular Motor","abstract":"Myosin Vc is the product of one of the three genes of the class V myosin found in vertebrates. It is widely found in secretory and glandular tissues, with a possible involvement in transferrin trafficking. Transient and steady-state kinetic studies of human myosin Vc were performed using a truncated, single-headed construct. Steady-state actin-activated ATPase measurements revealed a V(max) of 1.8 +/- 0.3 s(-1) and a K(ATPase) of 43 +/- 11 microm. Unlike previously studied vertebrate myosin Vs, the rate-limiting step in the actomyosin Vc ATPase pathway is the release of inorganic phosphate (~1.5 s(-1)), rather than the ADP release step (~12.0-16.0 s(-1)). Nevertheless, the ADP affinity of actomyosin Vc (K(d) = 0.25 +/- 0.02 microm) reflects a higher ADP affinity than seen in other myosin V isoforms. Using the measured kinetic rates, the calculated duty ratio of myosin Vc was approximately 10%, indicating that myosin Vc spends the majority of the actomyosin ATPase cycle in weak actin-binding states, unlike the other vertebrate myosin V isoforms. Consistent with this, a fluorescently labeled double-headed heavy meromyosin form showed no processive movements along actin filaments in a single molecule assay, but it did move actin filaments at a velocity of approximately 24 nm/s in ensemble assays. Kinetic simulations reveal that the high ADP affinity of actomyosin Vc may lead to elevations of the duty ratio of myosin Vc to as high as 64% under possible physiological ADP concentrations. This, in turn, may possibly imply a regulatory mechanism that may be sensitive to moderate changes in ADP concentration.","journal":"UNC Libraries","year":2021,"id":230428,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9613,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":353409,"name":"Mihály Kovács","orcid":"0000-0002-1200-4741","position":1,"is_corresponding":false},{"id":541382,"name":"Damon T. Jacobs","orcid":null,"position":2,"is_corresponding":false},{"id":320691,"name":"James R. Sellers","orcid":"0000-0001-6296-564X","position":3,"is_corresponding":false},{"id":275052,"name":"Richard E. Cheney","orcid":"0000-0001-6565-7888","position":4,"is_corresponding":false},{"id":434422,"name":"Ikuko Fujiwara","orcid":"0000-0002-9361-636X","position":5,"is_corresponding":false},{"id":306272,"name":"Yasuharu Takagi","orcid":null,"position":6,"is_corresponding":false},{"id":542861,"name":"Yi Yang","orcid":"0000-0002-7575-7046","position":0,"is_corresponding":true}],"reference_count":0,"raw_metadata":null,"created_at":"2026-07-18T23:55:05.844766Z","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":[]}