PROTEIN BODIES IN CORN ENDOSPERM ARE ENCLOSED BY AN ENMESHED IN F-ACTIN

When corn endosperm is gently homogenized in a microfilament-stabilizing buffer and filtrates centrifuged at very low g forces, abundant protein bodies are present in the pellet. When stained with both rhodamine-phalloidin and fluorescein-S(l)-myosin and viewed under epifluorescence, individual protein bodies appear to be enclosed in F-actin and groups of protein bodies appear to be enmeshed within a network of fine actin filaments. The yield of actin-enclosed protein bodies is not affected by the addition of non-ionic detergents to the grinding medium, but it is severely decreased with the addition of cytoskeleton-disrupting agents including Tris-HCl, KCl, KI, and ammonium sulphate, and the interconnecting fine filaments are totally abolished. Heparin, which interacts with membrane-cytoskeleton complexes, causes apparent coagulation of the protein bodies. The evidence from fluorescent microscopy suggesting that F-actin surrounds and enmeshes the protein bodies is supported by electron microscopy, gel electrophoresis, and Western blot analysis.