PDF Mechanics of Motor Proteins & the Cytoskeleton EBook - video dailymotionIntracellular cargo transport requires microtubule-based motors, kinesin and cytoplasmic dynein, and the actin-based myosin motors to maneuver through the challenges presented by the filamentous meshwork that comprises the cytoskeleton. Recent in vitro single molecule biophysical studies have begun to explore this process by characterizing what occurs as these tiny molecular motors happen upon an intersection between two cytoskeletal filaments. These studies, in combination with in vivo work, define the mechanism by which molecular motors exchange cargo while traveling between filamentous tracks and deliver it to its destination when going from the cell center to the periphery and back again. Cargo transport of organelles, secretory vesicles, and protein complexes by tiny molecular motors is an essential intracellular process. The importance of intracellular transport is highlighted by the fact that mutations to these motors lead to genetic diseases such as amyotrophic lateral sclerosis [ 1 ], parapalegia [ 2 ], and Griscelli syndrome type 1 [ 3 ]. Molecular motors that drive cargo transport along the cytoskeletal highway include myosins traveling along actin filaments and kinesin and cytoplasmic dynein motors traveling on microtubules Figure 1. These motors share cargo transport duties and face the challenge of maneuvering through a complex cytoskeleton with numerous microtubule and actin filament intersections.
Mechanics of Motor Proteins and the Cytoskeleton
Cells make use of molecular motors to transport small molecules, macromolecules and cellular organelles to target region to execute biological functions, which is utmost important for polarized cells, such as neurons. In particular, cytoskeleton motors play fundamental roles in neuron polarization, extension, shape and neurotransmission. Cytoskeleton motors comprise of myosin, kinesin and cytoplasmic dynein. F-actin filaments act as myosin track, while kinesin and cytoplasmic dynein move on microtubules. Cytoskeleton motors work together to build a highly polarized and regulated system in neuronal cells via different molecular mechanisms and functional regulations. This review discusses the structures and working mechanisms of the cytoskeleton motors in neurons. A neuron cell is highly polarized, composing of a cell body, an axon and dendrites.
Myosin motors power movements on actin filaments, whereas dynein and kinesin motors power movements on microtubules. The mechanisms of these motor proteins differ, but, in all cases, ATP hydrolysis and subsequent release of the hydrolysis products drives a cycle of interactions with the track either an actin filament or a microtubule , resulting in force generation and directed movement. Motor Proteins H. Lee Sweeney 1 and Erika L. Also in this Collection.