title: aPKC phosphorylation of Bazooka defines the apical/lateral border in Drosophila epithelial cells.
abstract: Bazooka (PAR-3), PAR-6, and aPKC form a complex that plays a key role in the polarization of many cell types. In epithelial cells, however, Bazooka localizes below PAR-6 and aPKC at the apical/lateral junction. Here, we show that Baz is excluded from the apical aPKC domain in epithelia by aPKC phosphorylation, which disrupts the Baz/aPKC interaction. Removal of Baz from the complex is epithelial-specific because it also requires the Crumbs complex, which prevents the Baz/PAR-6 interaction. In the absence of Crumbs or aPKC phosphorylation of Baz, mislocalized Baz recruits adherens junction components apically, leading to a loss of the apical domain and an expansion of lateral. Thus, apical exclusion of Baz by Crumbs and aPKC defines the apical/lateral border. Although Baz acts as an aPKC targeting and specificity factor in nonepithelial cells, our results reveal that it performs a complementary function in positioning the adherens junction in epithelia.
authors.affiliation: The Gurdon Institute and the Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.
authors.forename: Eurico
authors.initials: E
authors.lastname: Morais-de-Sá
authors.forename: Vincent
authors.initials: V
authors.lastname: Mirouse
authors.forename: Daniel
authors.initials: D
authors.lastname: St Johnston
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism*; D005260:Female; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D006080:Ovarian Follicle / Q000378:metabolism; D010053:Ovary / Q000166:cytology / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D017434:Protein Structure, Tertiary
chemical_list: D029721:Drosophila Proteins; D047908:Intracellular Signaling Peptides and Proteins; C400774:baz protein, Drosophila; C115015:PKC-3 protein; C532584:Par-6 protein, Drosophila; D011493:Protein Kinase C