October 1, 2012

There are a few things in our world that only turn to the right—Derek Zoolander and UPS trucks, for example. Maybe they could be inspired by the images above of myosin IC, which turns in left-hand curves.

Myosins are actin-based motors that function in countless cell processes. Class I myosins link cell membranes with the actin cytoskeleton and bind directly to lipid membranes. Within this class of myosins, myo1c is important in hearing, endocytosis, and membrane trafficking, and binds to the lipid phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2). A recent paper describes the ability of myo1c to drive actin motility on membranes containing PtdIns(4,5)P2. Pyrpassopoulos and colleagues found that myo1c motility occurs along counter-clockwise curved paths (top image above). This curved motility is not typical of other class I myosins—myo1a, for example, drives actin gliding in a straight line (bottom image above). In the images above, the actin filaments’ paths are in green, while the starting position of the filament is in orange.

BONUS!! Additional recent work from this research group describes the kinetic and mechanical properties of myo1c. Based on the results from this work, Greenberg and colleagues propose that myo1c functions as a slow transporter rather than a tension-sensitive anchor. 

ResearchBlogging.orgSerapion Pyrpassopoulos, Elizabeth A. Feeser, Jessica N. Mazerik, Matthew J. Tyska, & E. Michael Ostap (2012). Membrane-Bound Myo1c Powers Asymmetric Motility of Actin Filaments Current Biology, 22 (18), 1688-1692 DOI: 10.1016/j.cub.2012.06.069 
Copyright ©2012 Elsevier Ltd. All rights reserved.

Michael J. Greenberg, Tianming Lin, Yale E. Goldman, Henry Shuman, & E. Michael Ostap (2012). Myosin IC generates power over a range of loads via a new tension-sensing mechanism Proc Natl Acad Sci USA, 109 (37) DOI: 10.1073/pnas.1207811109

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