Septin filament and function in yeast and human cells . (A) Illustration showing members of the septin protein family in yeast (top) and humans (bottom), as well as homology groups in humans and proposed hetero-oligomeric complexes. (B) Illustration showing Cdc11a- or Cdc11b-capped octamers that form long and short filaments, respectively (top). Cartoon of A. gossypii morphology, sites of septin enrichment, and shape defects observed upon listed mutations (bottom; as shown by Cannon et al.). (C) Cartoon showing actin stress fibers in U20S human cells (top), and illustration of how septins connect actin to membranes (bottom; as shown by Martins et al.).