Properties of glycoprotein particles and their changes during development of sea urchin eggs and embryos

Abstract

1. 1. A singular proteinous component was isolated from the 105 000 g supernatant of morulae of Anthocidaris crassispina and Hemicentrotus pulcherrimus. The component was considered to consist of particles of 26S of S 20,w from its sedimentation patterns at ultracentrifugation. The 26S particles contain carbohydrates such as hexoses and hexosamines at 8.8 and 3.7, respectively, as values relative to a protein content of 100. 2. 2. The 26S glycoprotein particles were shown to be composed of several heterogeneous subunits, dissociated by 8 M urea treatment and separated by electrophoresis through a polyacrylamide gel column containing 6 M urea. None of the subunit bands of the 26S particles in electrophoresis corresponded to any of the bands formed by electrophoresis of yolk granules treated in the same way. 3. 3. Sedimentation properties of the 26S particles were studied during embryonic and larval development. The results indicated that the particles became lighter stepwise by about 1.5S, first at mesenchymal blastula and then at pluteus stage, as estimated by density gradient centrifugation. By analytical centrifugation, the 26S particles were estimated to become about 22S at pluteus stage. 4. 4. Quantitative changes of the 26S particles were also observed to occur in the course of development in parallel with the changes in sedimentation constant. 5. 5. In keeping with the changes in their sedimentation properties, changing patterns of subcomponent composition of the 26S particles were revealed by gel electrophoresis. Changes in the electrophoretic pattern were also observed to occur simultaneously at mesenchyme blastula and pluteus stages. A tentative idea is presented for the molecular events causing the developmental changes in characteristics of the particles, as seen from the electrophoretic patterns of the 26S particles treated in these ways.