Fig. 4.

Plekhg5 is apically localized in the superficial epithelial cells. (A) GFP-tagged Plekhg5 protein is detected at the apical cell cortex in the superficial epithelial cells (arrows), but is diffuse in deeper ectodermal cells. (B) Plekhg5 contains a PH domain and a PBM in addition to the GEF domain. Analyses of the deletion mutants that lack one of these domains reveal that removal of the PH domain, but not the PBM motif, abolishes the ability of the protein to induce ectopic blastopore lip. In addition, a point mutation that alters the conserved threonine 365 residue in the GEF domain into phenylalanine also results in non-functional Plekhg5. Numbers in each image indicate embryos exhibiting the ectopic blastopore lip-like morphology over the total number of embryos. (C) Deletion of the PH domain, but not the PBM, results in loss of apical accumulation of the proteins. The T365F GEF mutant protein can be recruited to the cell junctions in epithelial cells (arrows), but is not enriched at the apical cell cortex.