The role of Su(dx), an E3 class Ubiquitin ligase, in Notch pathway regulation. S.L. Mazaleyrat , D. Evans , H. Aslam , M. Fostier , M. Baron. School of Biological Sciences, University of Manchester, Manchester, United Kingdom.

   Suppressor of deltex (Su(dx)) is a negative regulator of the Notch pathway which encodes an E3 ubiquitin ligase. This class of enzyme targets specific proteins for ubiquitin-mediated degradation. Su(dx) contains three types of domain: a C2 domain necessary for membrane association, 4 WW domains which mediate protein-protein interactions and a HECT domain which catalyses the addition of multiple ubiquitin molecules to the target protein. We have investigated the nature of Su(dx) dependent regulation by the screening of a Drosophila expression library identifying several interacting proteins, also by the identification of genetic interactors and the localisation of Su(dx) within the cell. By conducting mis-expression studies we have also observed that Su(dx) over-expression results in both cell proliferation and cell differentiation phenotypes.