Article

Principles of unconventional Myosin function and targeting

Department of Biochemistry, Stanford University, Stanford, California 94305, USA.
Annual Review of Cell and Developmental Biology (Impact Factor: 20.24). 05/2011; 27:133-55. DOI: 10.1146/annurev-cellbio-100809-151502
Source: PubMed

ABSTRACT Unconventional myosins are a superfamily of actin-based motors implicated in diverse cellular processes. In recent years, much progress has been made in describing their biophysical properties, and headway has been made into analyzing their cellular functions. Here, we focus on the principles that guide in vivo motor function and targeting to specific cellular locations. Rather than describe each motor comprehensively, we outline the major themes that emerge from research across the superfamily and use specific examples to illustrate each. In presenting the data in this format, we seek to identify open questions in each field as well as to point out commonalities between them. To advance our understanding of myosins' roles in vivo, clearly we must identify their cellular cargoes and the protein complexes that regulate motor attachment to fully appreciate their functions on the cellular and developmental levels.

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    • "The MLC is an essential component of this family that is responsible for cytoskeletal dynamics for communication, migration and cell division (Sellers, 2000; Redowicz, 2007; Hartman et al., 2011) Myosin has an important role in the processes related to structural stabilization and cellular dynamics, rendering the cell membrane resistant to potential deformations. Furthermore, myosin is involved in actin-enabled motor mechanisms and the organization of actin in the intracellular space (Hartman et al., 2011; Kneussel and Wagner, 2013). FLNa, a substrate of PAK, is also an important cellular structural component. "
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    • "The first two act as motors on microtubule filaments, while myosins function on actin (Vale 2003). Myosins participate in a variety of cellular processes, including cytokinesis , organellar transport, cell polarization, transcriptional regulation, intracellular transport, and signal transduction (Hofmann et al. 2009; Bloemink and Geeves 2011; Hartman et al. 2011). They bind to filamentous actin and produce physical forces by hydrolyzing ATP and converting chemical energy into mechanical force (Hartman and Spudich 2012). "
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    • "However, loop regions that control functional features, such as actin binding and nucleotide binding, appear to be actually more constrained than the sequences of the rest of the myosin molecule (Goodson et al., 1999). Although the motor domain is structurally conserved throughout the myosin superfamily, critical features of the motor such as the ability to produce force and movement against an external load, processivity of movement, and the regulation of motor activity by ion binding or posttranslational modifications can differ greatly between myosin isoforms (Hartman et al., 2011). Four structural subdomains can be distinguished, the N-terminal subdomain, the upper (U50) and lower (L50) 50 kDa subdomains, and the converter (Figure 1). "
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