Septins may form a ubiquitous family of cytoskeletal filaments

T HIS minireview discusses recent information about the septin family of proteins, which suggests that the septins may be elements of a new filament system that functions in all or most eukaryotic cells. Septins are found in a wide variety of eukaryotes, are important for cytokinesis, and may compose or regulate a ubiquitous filament system that has not been previously recognized. A more extensive review of septins was recently published (26). This minireview also presents a new comparison of septin sequences. Actin filaments, microtubules, intermediate filaments, and myosin thick filaments, have been extensively studied over the past several decades, using methodologic advances in electron and light microscopy, detergent extraction of cells, and purification of proteins. This collection of filaments has been assumed to represent a fairly complete picture of the cytoskeletal filaments commonly found in eukaryotes. However, recent work suggests that cells augment these common cytoskeletal elements with additional elements, at least one of which, the septins, appears to be widely expressed and used for essential cell processes.