Lgl antagonizes Par complex membrane association to enable neural stem cell asymmetric division.

The Par complex regulates cell polarity in diverse animal cells, but how it is restricted to a specific membrane domain remains unclear. The tumor suppressor Lethal giant larvae (Lgl) is thought to inhibit Par complex membrane binding, yet in metaphase Drosophila neural stem cells (NSCs), Lgl is cytoplasmic while the Par complex is apically polarized, raising the question of how Lgl controls Par localization when it is not on the membrane. Using live imaging, we found that Lgl and atypical Protein Kinase C (aPKC) exhibit tightly coordinated, opposing membrane dynamics: aPKC displaces Lgl at mitotic entry, while Lgl displaces aPKC at mitotic exit. In Lgl-depleted NSCs, aPKC is not fully cleared from the membrane after mitosis, and this residual aPKC persists into the subsequent division, disrupting Miranda polarization. Apical aPKC recruitment still occurs, indicating that Lgl is not required for Par polarization per se, but rather for ensuring aPKC absence from the basal membrane before mitosis. These findings reveal a temporal mode of mutual antagonism between Lgl and the Par complex that may license proper asymmetric division.