Another Cytoskeleton in the Closet

Many eukaryotic cells contain up to three families of cytoskeletal proteins that are responsible for the spatial organization of the cell. Although the prokaryotic origins of the actin and tubulin families have now been established, the origin of the third was unknown. In this issue of Cell, provide evidence that the third family, comprising the intermediate filaments, also has origins in bacteria and is responsible for producing curved cells.