Sea urchin egg tropomyosin isoforms with muscle-type and nonmuscle-type antigenicities.

Egg tropomyosins were prepared from four sea urchin species, Stronglyocentrotus intermedius, Anthocidaris crassispina, Hemicentrotus pulcherrimus and Pseudocentrotus depressus, and their molecular heterogeneity was investigated by electrophoresis and immunoblotting. The molecular heterogeneity of egg tropomyosins was species-specific, and two to four kinds of tropomyosin isoforms were detected, the apparent molecular weights of which were 29,000-32,000. The egg tropomyosin isoforms could be classified into two groups with muscle- and nonmuscle-type antigenicities in each species. No obvious difference in their cytological localization was observed immunocytochemically in S. intermedius and H. pulcherrimus.