Characterization of myosin‐II binding to Golgi stacks in vitro

Medientyp: E-Artikel

Titel: Characterization of myosin‐II binding to Golgi stacks in vitro

Beteiligte: Fath, Karl R.

Erschienen: Wiley, 2005

Sprache: Englisch

DOI: 10.1002/cm.20060

ISSN: 0886-1544

Schlagwörter: Cell Biology ; Structural Biology

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Beschreibung: AbstractIn addition to important roles near the actin‐rich cell cortex, ample evidence indicates that multiple myosins are also involved in membrane movements in the endomembrane system. Nonmuscle myosin‐II has been shown to have roles in anterograde and retrograde trafficking at the Golgi. Myosin‐II is present on Golgi stacks isolated from intestinal epithelial cells and has been localized to the Golgi in several polarized and unpolarized cell lines. An understanding of roles of myosin‐II in Golgi physiology will be facilitated by understanding the molecular arrangement of myosin‐II at the Golgi. Salt‐washing removes endogenous myosin‐II from isolated Golgi and purified brush border myosin‐II can bind in vitro. Brush border myosin‐II binds to a tightly bound Golgi peripheral membrane protein with a K1/2 of 75 nM and binding is saturated at 0.7 pmol myosin/μg Golgi. Binding studies using papain cleavage fragments of brush border myosin‐II show that the 120‐kDa rod domain, but not the head domain, of myosin heavy chain can bind directly to Golgi stacks. The 120‐kDa domain does not bind to Golgi membranes when phosphorylated in vitro with casein kinase‐II. These results suggest that phosphorylation in the rod domain may regulate the binding and/or release of myosin‐II from the Golgi. These data support a model in which myosin‐II is tethered to the Golgi membrane by its tail and actin filaments by its head. Thus, translocation along actin filaments may extend Golgi membrane tubules and/or vesicles away from the Golgi complex. Cell Motil. Cytoskeleton 60:222–235, 2005. © 2005 Wiley‐Liss, Inc.

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