Scaffolding protein that facilitates the localization of proteins to the cell membrane (PubMed:11927608, PubMed:16678097, PubMed:22006950). Required for the correct formation of tight junctions and epithelial apico-basal polarity (PubMed:11927608, PubMed:16678097). Positively regulates epithelial cell microtubule elongation and cell migration, possibly via facilitating localization of PRKCI/aPKC and PAR3D/PAR3 at the leading edge of migrating cells (By similarity). Plays a role in the correct reorientation of the microtubule-organizing center during epithelial migration (By similarity). May regulate the surface expression and/or function of ASIC3 in sensory neurons (By similarity). May recruit ARHGEF18 to apical cell-cell boundaries (PubMed:22006950).