Identification of phosphorylation sites on Numb and Miranda by atypical protein kinase c

摘要

In drosophila, as for vertebrates, asymmetric cell divisions play an important role in the development of the nervous system resulting in segregation of specific proteins following cell division. In neuroblasts and sensory organ precursors, the fate determinant Numb localizes asymmetrically into the anterior daughter cell, where it influences cell fate by repressing the signal transduction pathway of the Notch receptor. Cortical membrane localization of mammalian Numb is dynamically regulated in response to PKC dependent signaling pathways1,2. In the present investigation, mass spectrometry was used to identify the phosphorylation sites of two potential substrates of aPKC: Numb, and Miranda. The functional significance of phosphorylation sites on asymmetric cell localization was obtained through site mutagenesis experiments.