Large Vesicle Moves in Rolling Manner by Myosin 5C along Actin Tracks

Abstract

Class 5 myosins are actin-based molecular motors implicated in intracellular cargo transport. In vertebrates, myosin 5 (Myo5) consists of three isoforms, named myosin 5a, 5b, and 5c. The ability of myosin V molecules to move continuously along actin filaments (i.e. processivity) is required for efficient cargo transport in cells. This physical property has been well addressed in Myo5a and 5b, which demonstrate processive movement as a single molecule. In contrast, Myo5c shows no processivity as a single molecule, although it is found in cargo and is believed to participate in cargo transports. This raises the possibility that multiple Myo5c molecules should transport cargos. Recent studies have shown that Myo5c binds to Zymogen granule (ZGs) in pancreatic cells and transports ZGs to cell periphery. Purified ZGs was investigated the movement manner in vitro. The velocity and run-length of ZGs along actin track was measured (99 nm/sec and 1255 nm, respectively). We identified that the movement manner of ZGs move in rolling manner instead of gliding along actin tracks. Mathematical model of multiple Myo5c motors ensemble applied to understand the movement behavior vs. number of Myo5c on the vesicle.