THE GASTRULATION DEFECTIVE GENE OF DROSOPHILA-MELANOGASTER IS A MEMBER OF THE SERINE-PROTEASE SUPERFAMILY

The establishment of dorsal-ventral polarity in the oocyte involves tw o sets of genes. One set belongs to the gurken-torpedo signaling pathw ay and affects the development of the egg chorion as well as the polar ity of the embryo, The second set of genes affects only the dorsal-ven tral polarity of the embryo but not the eggshell, gastrulation defecti ve is one of the earliest acting of this second set of maternally requ ired genes. We have cloned and characterized the gastrulation defectiv e gene and determined that it encodes a protein structurally related t o the serine protease superfamily, which also includes the Snake, East er, and Nudel proteins. These data provide additional support for the involvement of a protease cascade in generating an asymmetric signal ( i.e., asymmetric Spatzle activity) during establishment of dorsal-vent ral polarity in the Drosophila embryo.