The three-dimensional structures of myosin subfragment 1 (S1), gelsoli
n segment 1 complexed with alpha-actin, villin fragment 14T, Acanthamo
eba profilin-I, and bovine profilin complexed with beta-actin were com
pleted last year. Together, they expand our understanding of the struc
tural organization of actin-binding proteins. In addition, the segment
1 and bovine profilin complexes provide atomic-level descriptions of
their interfaces with actin.