Protease-sensitive component(s) on the cell surface prevents self-fusion in a bisexual strain of Dictyostelium discoideum.

The sexual cycle of the cellular slime mold Dictyostelium discoideum offers a suitable system to analyze the mechanism of cell recognition during mating. Sexual cell fusion in D. discoideum typically occurs between complementary heterothallic strains. In addition, several bisexual strains are known which undergo sexual cell fusion with heterothallic strains of either mating type, but cannot do so by themselves. In the present study, trypsin digestion of cell surface molecules was found to induce self-fusion in a bisexual strain WS2162, suggesting the presence on the cell surface of a self-recognition molecule whose homophilic interaction interferes with the cell fusion mechanism.