Structure of the acrosomal bundle

  title={Structure of the acrosomal bundle},
  author={Michael F. Schmid and Michael P. Sherman and Paul Matsudaira and Wah Chiu},
In the unactivated Limulus sperm, a 60-µm-long bundle of actin filaments crosslinked by the protein scruin is bent and twisted into a coil around the base of the nucleus. At fertilization, the bundle uncoils and fully extends in five seconds to support a finger of membrane known as the acrosomal process. This biological spring is powered by stored elastic energy and does not require the action of motor proteins or actin polymerization. In a 9.5-Å electron cryomicroscopic structure of the… CONTINUE READING