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Logo of jbcThe Journal of Biological Chemistry
J Biol Chem. 2012 September 7; 287(37): 31454.
PMCID: PMC3438975

How Actin Branches out in New Directions♦

The Conformational State of Actin Filaments Regulates Branching by Actin-related Protein 2/3 (Arp2/3) Complex

♦ See referenced article, J. Biol. Chem. 2012, 287, 31447–31453

Actin, a cytoskeleton protein, plays a critical role in cell motility. A cell's ability to move is driven by the assembly of actin at cell protrusions. The actin assembly involves actin-binding proteins, such as the actin-related protein 2/3 (Arp2/3) complex. This complex helps to form branched actin structures. It picks out specific actin networks for binding, but how it does that is not well understood. In this Paper of the Week, a team led by Chih-Lueh Albert Wang at the Boston Biomedical Research Institute used in vitro imaging and binding assays to demonstrate that caldesmon, an actin-binding protein, increased the Arp2/3-mediated branching activity at newly formed actin filaments. Caldesmon had no effect on branch formation at older actin filaments, suggesting that the protein maintained freshly polymerized actin in a state with a higher affinity for the Arp2/3 complex. The authors say, “This presents a novel regulatory mechanism by which caldesmon, and potentially other actin-binding proteins, regulates the interactions of actin with its binding partners.”

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Representative images of actin assembly.

Articles from The Journal of Biological Chemistry are provided here courtesy of American Society for Biochemistry and Molecular Biology