AN INTRINSIC DOMINANT-NEGATIVE ACTIVITY OF SERRATE THAT IS MODULATED DURING WING DEVELOPMENT IN DROSOPHILA

The Serrate and Delta genes of Drosophila encode two transmembrane pro teins that act as ligands for the Notch receptor. Both have been shown to promote Notch activity during wing development and the specificati on of cell fate during neurogenesis. This observation has led to the s uggestion that Serrate and Delta are functionally equivalent ligands f or Notch. In this study we compare the activities of these proteins du ring wing development. Our results show that Serrate can activate or i nactivate Notch in a concentration-dependent manner. While the inactiv ation is likely to be mediated by a dominant negative effect over Notc h, the activation is similar to that elicited by Delta and requires th e product of the Suppressor of Hairless gene. These results indicate t hat regulation of the concentration of Serrate during development must be an important way of regulating its activity. (C) 1997 Academic Pre ss.