title: The yeast class V myosins, Myo2p and Myo4p, are nonprocessive actin-based motors.
abstract: The motor properties of the two yeast class V myosins, Myo2p and Myo4p, were examined using in vitro motility assays. Both myosins are active motors with maximum velocities of 4.5 microm/s for Myo2p and 1.1 microm/s for Myo4p. Myo2p motility is Ca(2+) insensitive. Both myosins have properties of a nonprocessive motor, unlike chick myosin-Va (M5a), which behaves as a processive motor when assayed under identical conditions. Additional support for the idea that Myo2p is a nonprocessive motor comes from actin cosedimentation assays, which show that Myo2p has a low affinity for F-actin in the presence of ATP and Ca(2+), unlike chick brain M5a. These studies suggest that if Myo2p functions in organelle transport, at least five molecules of Myo2p must be present per organelle to promote directed movement.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Reck-Peterson
authors.forename: M J
authors.initials: MJ
authors.lastname: Tyska
authors.forename: P J
authors.initials: PJ
authors.lastname: Novick
authors.forename: M S
authors.initials: MS
authors.lastname: Mooseker
mesh_terms: D000199:Actins / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D000906:Antibodies / Q000276:immunology; D001921:Brain; D002118:Calcium / Q000494:pharmacology; D002148:Calmodulin-Binding Proteins / Q000276:immunology / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D002645:Chickens; D005656:Fungal Proteins / Q000378:metabolism*; D007700:Kinetics; D018715:Microscopy, Video; D020409:Molecular Motor Proteins / Q000276:immunology / Q000378:metabolism*; D009068:Movement / Q000187:drug effects; D018995:Myosin Heavy Chains; D024462:Myosin Type II; D024701:Myosin Type V; D009218:Myosins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000276:immunology / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins
chemical_list: D000199:Actins; D000906:Antibodies; D002148:Calmodulin-Binding Proteins; D002352:Carrier Proteins; D005656:Fungal Proteins; C077512:MYO2 protein, S cerevisiae; C434211:MYO2 protein, S pombe; D020409:Molecular Motor Proteins; C098732:Myo4 protein, S cerevisiae; D009419:Nerve Tissue Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C078829:chicken brain myosin-V p190; D000255:Adenosine Triphosphate; D024462:Myosin Type II; D024701:Myosin Type V; D018995:Myosin Heavy Chains; D009218:Myosins; D002118:Calcium