Changes in membrane protein during the development of macrocysts in physarum polycephalum

Plasma membranes were isolated from the acellular slime mold Physarum polycephalum at different developmental stages in macrocyst formation and the protein composition was analyzed by polyacrylamide gel electrophoresis. Turnover of membrane protein was also studied by pulsechase experiments with ³⁵S-methionine. Surface proteins on the plasma membrane which were labeled by the lactoperoxidase-catalyzed iodination of intact plasmodia were also labeled with Concanavalin A, indicating that these components are glycosylated. The glycoproteins of the plasma membrane of vegetative plasmodia were largely conserved during the development of macrocysts. However, the relative amounts of these proteins showed significant changes and a few components were transiently accumulated in the plasma membrane. These facts suggest that the morphogenic events are accompanied by alterations in protein composition in the plasma membrane.