An aPKC rheostat induces apical contraction in response to epithelial stretching

Apical-basal polarity in epithelial cells is controlled by a conserved set of polarity factors that define the apical, junctional and basolateral domains of the cell, but how these factors adapt to or control changes in domain sizes during cell shape changes remains unclear. Atypical protein kinase C (aPKC) is the main effector of apical identity, phosphorylating the lateral factors, Bazooka/Par-3, Lgl, Par-1 and Yurt to exclude them from the apical domain. Using analogue-sensitive aPKC in Drosophila follicle cells, we found that aPKC substrates differ over 100-fold in their sensitivity to inhibition, revealing a hierarchy of substrates, that is conserved in mammals, in which high-affinity s