Inhibition of conjugation in Tetrahymena pyriformis by concanavalin A. Binding of concanavalin A to material secreted during starvation and to washed cells

A group of glycoproteins which form an insoluble complex with concanavalin A (ConA) are secreted during starvation of the mating types strain, as well as by the non-mating types of Tetrahymena pyriformis. These glycoproteins were isolated by Sepharose-ConA, characterized, and their relevance to the conjugation process studied. The isolated ConA binding proteins (CBM) contain about 26% of their total weight, a phenol sulfuric acid-positive material, presumably carbohydrates, and exhibit about 5-8 major bands by gel electrophoresis analysis. The possibility that ConA inhibits the conjugation process by precipitating with this material was tested. Addition of isolated CBM restored conjugation previously inhibited by ConA. However, incubation of isolated CBM with either of the mating types or with both did not have any effect on the kinetics of the conjugation process. Antibodies prepared against CBM-secreted by both mating types did not prevent conjugation when added to the conjugation medium. The data suggest that CBM does not directly participate in the conjugation process. Inhibition of conjugation by ConA is probably due to its interaction with specific membrane-bound glycoproteins.