{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Villin is an actin-binding protein that contains gelsolin domains capped by a ”headpiece” at the C-terminus consisting of a fast and independently-folding three-helix bundle stabilized by hydrophobic interactions. The headpiece domain is a commonly-studied protein in molecular dynamics due to its fast-folding kinetics and short primary sequence. Villin is a regulator of the actin cytoskeleton involved in the bundling, capping, and severing actin filaments. This allows cells to maintain shape, enable cell movement, and organize actin filaments within the microvilli. Villin is expressed in epithelial cells, particularly in the brush border area in the gastrointestinal mucosal epithelium and kidney proximal tubules."}]}]}