HOUSTON, Oct. 10, 2006 -- Like all good baseball players, the protein calmodulin appreciates the importance of maintaining a good grip. A vital regulatory protein in all plants and animals, calmodulin is known to grab hold of hundreds of different proteins inside our cells, and it typically uses a grip that would make a Little League coach proud: it holds its two clasping lobes firmly together, one atop the other, like the hands of a big league slugger.

In a surprising find, researchers from Rice University and the University of Texas Health Science Center at Houston (UT-Houston) report in the Oct. 11 issue of Structure the first-ever case of calmodulin using a different kind of grip, a more open grasp that's reminiscent of a batter trying to lay down a bunt.

"If your hands are together, your arms operate as one unit," said Rice co-author Kevin MacKenzie, demonstrating a swing with an imaginary bat. "But when you bunt," he said, sliding one hand up into the classic bunter's stance, "your arms operate independently, and that's what we're seeing calmodulin do in this case."

Calmodulin is a vital biochemical player in life forms that range from fungi to humans. Its utility lies in its ability to pass on signals both outside and inside of cells. It does this by carrying out one specialized function: it binds with calcium ions and changes shape when it does so. As it changes shape, it grabs hold or lets go of other proteins.

"Nature could have selected a system where each protein bound calcium on its own, but instead it uses calmodulin for that and then has calmodulin interact with the other proteins," said MacKenzie, assistant professor of biochemistry and cell biology.

One of calmodulin's roles in muscle cells comes in regulating the flow of calcium ions into the cell. When your nerve sends a signal to your heart to beat or your arm to move, the signal causes tiny compartments of calcium inside the muscle cells to op
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Contact: Jade Boyd
jadeboyd@rice.edu
713-348-6778
Rice University
10-Oct-2006