Tropomyosin in the sea urchin egg cortex.
Tropomyosin was purified from the Triton-treated cortex fraction of fertilized sea urchin egg. Egg tropomyosin showed characteristics typical of nonmuscle tropomyosins such as low molecular mass, short periodicity of Mg2+-paracrystals, low lysine/arginine ratio, high Mg2+ requirement in binding to F-actin, in addition to the properties of all tropomyosins, namely, stability to high temperature, anomalous migration of SDS/urea gel, dissociation from F-actin under high ionic conditions and very acidic isoelectric point. Co-sedimentation assay of egg tropomyosin with actin in the presence of the previously purified high-molecular-mass actin binding protein (260-kDa protein) showed that these two proteins bind to actin filaments in a non-competitive manner. This suggested that both the proteins play a cooperative role in the formation of actin-filament-based cytoskeletal structure in the cortex.
Maekawa
S
S
Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Japan.
Toriyama
M
M
Sakai
H
H
D000199:Actins / Q000378:metabolism; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D008970:Molecular Weight; D010063:Ovum / Q000032:analysis*; D011485:Protein Binding; D012617:Sea Urchins; D014335:Tropomyosin / Q000302:isolation & purification* / Q000378:metabolism; D015053:Zygote / Q000032:analysis*
D000199:Actins; D000596:Amino Acids; D014335:Tropomyosin