An evolutionarily conserved PB domain in Lgl mediates its PM targeting. (A) Lgl contains a conserved PB domain. (Bottom) Surface and cartoon models of Sro7 structure (Protein Data Bank accession no. 2OAJ; Hattendorf et al., 2007) rendered by PyMOL software. β sheets are in green to highlight the WD40 blades, of which each contains four β sheets. The “loop” in between WD40 blade 10 and 11 is in magenta. (Top) Alignment of the loop regions between 10D and 11A β sheets in Lgl or Sro7. Positively charged Lys and Arg residues within the loop sequences are in red, and PB domains are boxed. Blue arrowheads point to the conserved Ser residues (in blue) that can be phosphorylated by aPKC (Ser residues in green numbers are also Aurora kinase phosphorylation sites). Ser residues were numbered based on Drosophila Lgl (dLgl) isoform A (gi24464586). hLgl1/2, human Lgl1/2 (gi 62912476 and 40674459); mLgl1/2, mouse Lgl1/2 (gi 56800067 and 21703874); S_Sro7, Saccharomyces cerevisiae Sro7 (gi 6325289). Sequence alignments are modified from Hattendorf et al. (2007). Complete sequence alignments can be found in Fig. S2 by Hattendorf et al. (2007). (B) Subcellular localization of mLgl::GFP (WT), mLgl^ΔPB::GFP (ΔPB), mLgl^K6A::GFP (K6A; all six lysines mutated to alanine), and mLgl^KR13A::GFP (KR13A; all 13 lysines and arginines mutated to alanine) in HEK293 cells (n = 6). (C) GFP fused with wild-type loop of mLgl (Loop^WT::GFP), but not loops carrying K6A or KR13A mutations (Loop^K6A::GFP and Loop^KR13A::GFP, respectively), targets to the PM in HEK293 cells. Loop^WT::GFP is also nuclear (n = 6 for each sample). **, P < 0.01; ***, P < 0.001. Bars, 5 µm. Error bars represent means ± SEM.