Centrosomes: Sfi1p and centrin unravel a structural riddle.

The discovery of Sfi1p as a novel binding partner for the Ca2+-binding protein centrin has provided new insight into the dynamic behavior of centrosomes. Sfi1 binds to multiple centrin molecules along a series of internal repeats, and the complex forms Ca2+-sensitive contractile fibers that function to reorient centrioles and alter centrosome structure.