Myosin from alga Chara: unique structure revealed by electron microscopy.

Cytoplasmic streaming is a fundamental process for the transport of molecules and organelles in plant cells. A myosin-like protein responsible for cytoplasmic streaming in fresh water alga, Chara corallina, has been purified. Electron micrographs of this protein revealed that it has two heads with similar size and shape to those of muscle myosin (myosin II) but its tail was shorter than that of muscle myosin with a globular structure at its distal end like that of myosin V. The myosin cosedimented with vesicles composed of phosphatidyl serine like other non-muscle myosin species involved in intracellular transport.