title: Two heads of myosin are better than one for generating force and motion.
abstract: Several classes of the myosin superfamily are distinguished by their "double-headed" structure, where each head is a molecular motor capable of hydrolyzing ATP and interacting with actin to generate force and motion. The functional significance of this dimeric structure, however, has eluded investigators since its discovery in the late 1960s. Using an optical-trap transducer, we have measured the unitary displacement and force produced by double-headed and single-headed smooth- and skeletal-muscle myosins. Single-headed myosin produces approximately half the displacement and force (approximately 6 nm; 0.7 pN) of double-headed myosin (approximately 10 nm; 1.4 pN) during a unitary interaction with actin. These data suggest that muscle myosins require both heads to generate maximal force and motion.
authors: Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405, USA.
authors: M J
authors: MJ
authors: Tyska
authors: D E
authors: DE
authors: Dupuis
authors: W H
authors: WH
authors: Guilford
authors: J B
authors: JB
authors: Patlak
authors: G S
authors: GS
authors: Waller
authors: K M
authors: KM
authors: Trybus
authors: D M
authors: DM
authors: Warshaw
authors: S
authors: S
authors: Lowey
mesh_terms: D000199:Actins / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002645:Chickens; D019281:Dimerization; D007700:Kinetics; D018482:Muscle, Skeletal / Q000502:physiology*; D009130:Muscle, Smooth / Q000502:physiology; D009218:Myosins / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D000199:Actins; D000255:Adenosine Triphosphate; D009218:Myosins