Evidence has been found of a role for Drosophila Psn in Notch processing.
Notch acts as a transmembrane cell-surface receptor for intercellular signals during development.
It has been proposed that signal transduction involves cleavage and transport of the Notch intracellular domain to the nucleus. To investigate the involvement of presenilin in proteolysis of Notch protein, an in vivo assay was used for ligand-dependent cleavage and nuclear access of the intracellular domain of Drosophila Notch. Both alleles are predicted to cause premature termination and appear to be null alleles. To generate embryos with no Psn activity, both maternal and zygotic Psn activity were removed by generating Psn minus embryos derived from Psn minus germ cells. In both Psn minus and Notch minus embryos, clusters of neuroblasts segregate at the positions normally occupied by single neuroblasts, as revealed by Hunchback staining.