Biomaterial Database

Unconventional processive mechanics of non-muscle myosin IIB. 2010

Melanie F Norstrom, and Philip A Smithback, and Ronald S Rock

Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60637, USA.

Proper tension maintenance in the cytoskeleton is essential for regulated cell polarity, cell motility, and division. Non-muscle myosin IIB (NMIIB) generates tension along actin filaments in many cell types, including neuronal, cardiac, and smooth muscle cells. Using a three-bead optical trapping assay, we recorded NMIIB interactions with actin filaments to determine if a NMIIB dimer cycles along an actin filament in a processive manner. Our results show that NMIIB is the first myosin II to exhibit evidence of processive stepping behavior. Analysis of these data reveals a forward displacement of 5.4 nm and, surprisingly, frequent backward steps of -5.9 nm. Processive stepping along the long pitch helix of actin may provide a mechanism for disassembly of fascin-actin bundles. Forward steps and detachment are weakly force-dependent at all forces, consistent with rate-limiting and force-dependent ADP release. However, backward steps are nearly force-independent. Our data support a model in which NMIIB can readily move in both directions at stall, which may be important for a general regulator of cytoskeleton tension.

UI	MeSH Term	Description	Entries
D008840	Microfilament Proteins	Monomeric subunits of primarily globular ACTIN and found in the cytoplasmic matrix of almost all cells. They are often associated with microtubules and may play a role in cytoskeletal function and/or mediate movement of the cell or the organelles within the cell.	Actin Binding Protein,Actin-Binding Protein,Actin-Binding Proteins,Microfilament Protein,Actin Binding Proteins,Binding Protein, Actin,Protein, Actin Binding,Protein, Actin-Binding,Protein, Microfilament,Proteins, Actin-Binding,Proteins, Microfilament
D008841	Actin Cytoskeleton	Fibers composed of MICROFILAMENT PROTEINS, which are predominately ACTIN. They are the smallest of the cytoskeletal filaments.	Actin Filaments,Microfilaments,Actin Microfilaments,Actin Cytoskeletons,Actin Filament,Actin Microfilament,Cytoskeleton, Actin,Cytoskeletons, Actin,Filament, Actin,Filaments, Actin,Microfilament,Microfilament, Actin,Microfilaments, Actin
D009068	Movement	The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.	Movements
D002352	Carrier Proteins	Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes.	Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
D002645	Chickens	Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.	Gallus gallus,Gallus domesticus,Gallus gallus domesticus,Chicken
D003599	Cytoskeleton	The network of filaments, tubules, and interconnecting filamentous bridges which give shape, structure, and organization to the cytoplasm.	Cytoplasmic Filaments,Cytoskeletal Filaments,Microtrabecular Lattice,Cytoplasmic Filament,Cytoskeletal Filament,Cytoskeletons,Filament, Cytoplasmic,Filament, Cytoskeletal,Filaments, Cytoplasmic,Filaments, Cytoskeletal,Lattice, Microtrabecular,Lattices, Microtrabecular,Microtrabecular Lattices
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D055595	Mechanical Phenomena	The properties and processes of materials that affect their behavior under force.	Mechanical Concepts,Mechanical Processes,Mechanical Phenomenon,Mechanical Process,Concept, Mechanical,Concepts, Mechanical,Mechanical Concept,Phenomena, Mechanical,Phenomenon, Mechanical,Process, Mechanical,Processes, Mechanical
D024501	Nonmuscle Myosin Type IIB	A nonmuscle isoform of myosin type II found predominantly in neuronal tissue.	Myosin IIB,Myosin Type IIB, Non-Muscle,Non-Muscle Myosin Type IIB,Myosin B,Myosin Type IIB, Non Muscle,Non Muscle Myosin Type IIB