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Izard Lab
Flexible molecular fingers stabilize cell movement
The physical stress on a cell's internal skeleton generated as the cell moves forward triggers a protein called alpha-actinin to partly unravel its own structure to free an internal molecular "arm" that reaches out to another protein, called vinculin. This triggers vinculin to partly unravel as well, freeing several molecular "fingers" that assume a shape that allows alpha-actinin to bind to it, according to images of this interplay produced by St. Jude investigators.
The binding of alpha-actinin to vinculin reinforces alpha-actinin's hold on protein rods called actin, which make up the cell's skeleton, the researchers said. This process stabilizes the skeleton during movement and lets the cell move in specific directions. For example, it allows cells in an embryo to migrate to take up their final positions; however, it also allows cancer cells to break away from a tumor and spread to other parts of the body.
The interaction of alpha-actinin and vinculin, captured in a computer-generated image that appears on the cover of the July 15 issue of Molecular and Cellular Biology, is based on results of X-ray crystallography studies led by Tina Izard, PhD, Hematology-Oncology, senior author of the paper.
The current article–the latest in a series of such articles that Izard's group has published– provides further evidence that, unlike the traditional view of a protein as having a single shape and function, vinculin can alter its shape to perform different jobs. Vinculin's ability to act as the cell's adaptable "monkey wrench" makes this protein a highly versatile molecule, Izard noted.
The other authors include Philippe Bois, PhD, Biochemistry; Robert Borgon of the University of Tennessee; and Clemens Vonrhein, Global Phasing Limited, Cambridge, United Kingdom.
Last update: August 2005
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