In search of novel interacting partners in Notch signaling. A. Mukherjee , A. Veraksa , S. Artavanis-Tsakonas. MGH Cancer Center, Harvard Medical School, Charlestown, MA.

   Over the past few years genetic analyses lead to the identification of several genes that are capable of modulating Notch signaling. In an attempt to identify Notch modulators based on their molecular interaction profile, we initiated a relatively large-scale yeast two-hybrid analysis involving 18 proteins that have been implicated in Notch signaling either by genetic or molecular means. This analysis was done, whenever possible, with the Drosophila as well as the human homologues. The baits that have identified novel interactors so far include Drosophila Notch, Delta, Serrate, Suppressor of Hairless, human Notch1, Notch2, Delta1, Jagged1, RBPJk, and other important genes related to this pathway such as Drosophila Deltex, Mastermind, Rab6, Dishevelled, Archipelago, and human Deltex. In addition to the yeast two-hybrid analysis, Drosophila Notch, Deltex and Mastermind proteins were tagged with an affinity module (TAP tag) and expressed in Drosophila cells and embryos. Protein complexes containing the baits and associated components were purified and analyzed by mass-spectrometry. We are focusing on several novel interactors that have been identified with both the yeast two-hybrid and the mass-spectrometric analyses. We will present evidence for a possible role of these novel interacting partners in Notch signaling.