Planar cell polarity (PCP) studies in the fly have identified several key proteins, such as Strabismus (Stbm), that are required for planar polarity decisions and act by forming asymmetrically localized complexes. In a study of how Stbm functions in this process, Bastock et al. now show, on , that Stbm localizes preferentially to the proximal edge of wing cells in the adherens junction zone where other PCP proteins, such as Dishevelled (Dsh) and Prickle (Pk),also localize. Here, Stbm binds directly to Dsh and Pk to recruit them to cell membranes – in its absence, both proteins become mislocalized. In a two-step model, the authors propose that Stbm acts with Frizzled and Flamingo to apicolaterally localize other PCP proteins, including Dsh and Pk. Dsh and Pk then mediate the asymmetric localization of these proteins to the proximal-distal axis.
