Multifunctional myosin VI has a multitude of cargoes

Abstract

In humans, a vast array of cytoskeletal motor proteins (19 dyneins, 43 kinesins, and 39 myosins) (1) move along microtubule and actin filament tracks to generate an enormous range of cellular functions. The kinesin and dynein motor proteins drive long-distance transport along microtubules, whereas the myosins are responsible for short-range delivery along actin filaments (2). The myosin motor proteins are composed of three functional domains: a motor domain with catalytic ATPase and actin-binding sites, a neck (lever arm with 1–6 bound calmodulins), and a cargo-binding tail domain. The mechanochemical properties of the myosins have been studied in great detail, but far less is known about their exact cellular functions (3). Although the kinetic properties of the motor domains of the myosins are fine-tuned for their cellular roles, it is the identity of their cargo-binding proteins that determines their precise cellular functions. In PNAS, Finan et al. (4) use a biochemical interaction screen to identify the cargo-binding partners of myosin VI/Jaguar in Drosophila to further our understanding of the cellular roles of this motor protein.