Date of Graduation


Document Type


Degree Type



Eberly College of Arts and Sciences



Committee Chair

Ashok P Bidwai


The Enhancer of split Complex (E(spl)C) in Drosophila melanogaster encodes seven bHLH repressors that serve as the final effectors of the highly conserved Notch signaling pathway during the process of cell fate specification. These E(spl) proteins have been considered to be functionally redundant because of their structural similarity, and the observation that over-expression of individual E(spl) members leads to neural hypoplasia, in general. And additional compounding factor is that loss-of function alleles in individual E(spl) members have been unavailable. However, individual E(spl) members exhibit inordinate conservation through Drosophila evolution and are differentially expressed, findings which challenge the premise of functional redundancy. Thus, I have carried out studies to compare the roles of two E(spl) proteins, M5 and M8, during eye and bristle development, with emphasis on their phosphorylation by protein kinase CK2. The function of the phosphorylation domain and its influence on repression by M8 has also been assessed. These studies suggest that M8 and M5 elicit suppression of bristle development with different potencies, and that phosphorylation does not engender redundant outcomes on repression in vivo. Finally, a number of novel proteins have been identified based on their interaction with the phosphorylation domain of M8 in a yeast two-hybrid screen. In conclusion, these studies suggest that E(spl) proteins serve non-redundant and, perhaps, context-specific roles.