Regulation of dorso/ventral patterning in the Drosophila embryo by multiple dorsal-interacting proteins.

The Rel family transcription factor, Dorsal, determines cell fate as a function of position along the dorsoventral axis of the Drosophila embryo. This process depends on interactions between Dorsal and a large number of additional proteins present in the early embryo. Cytoplasmic interactions regulate the nuclear uptake of Dorsal, resulting in the establishment of the Dorsal nuclear concentration gradient, which determines the dorsoventral polarity of the embryo. Nuclear protein-protein interactions then enable Dorsal to activate some target genes and to repress others, thereby promoting the division of the embryo into distinct developmental domains. Because of this broad array of regulatory interactions, Dorsal serves as an excellent paradigm for eukaryotic transcriptional regulation.