31088962 , Related PDB ids: 6N8P, 6N8Q, 6N8R, 6N8S
- Almagor L, Ufimtsev IS, Ayer A, Li J, Weis WI
- Structural insights into the aPKC regulatory switch mechanism of the human cell polarity protein lethal giant larvae 2.
- Proc Natl Acad Sci U S A. 2019 May 14. pii: 1821514116. doi:, 10.1073/pnas.1821514116.
- Metazoan cell polarity is controlled by a set of highly conserved proteins. Lethal giant larvae (Lgl) functions in apical-basal polarity through phosphorylation-dependent interactions with several other proteins as well as the plasma membrane. Phosphorylation of Lgl by atypical protein kinase C (aPKC), a component of the partitioning-defective (Par) complex in epithelial cells, excludes Lgl from the apical membrane, a crucial step in the establishment of epithelial cell polarity. We present the crystal structures of human Lgl2 in both its unphosphorylated and aPKC-phosphorylated states. Lgl2 adopts a double beta-propeller structure that is unchanged by aPKC phosphorylation of an unstructured loop in its second beta-propeller, ruling out models of phosphorylation-dependent conformational change. We demonstrate that phosphorylation controls the direct binding of purified Lgl2 to negative phospholipids in vitro. We also show that a coil-helix transition of this region that is promoted by phosphatidylinositol 4,5-bisphosphate (PIP2) is also phosphorylation-dependent, implying a highly effective phosphorylative switch for membrane association.