The Par3/Par6/aPKC complex and epithelial cell polarity

•The Par3/Par6/aPKC complex is a major cell polarity regulatory engine in all eukaryotes.•The Par complex functions as a hub interacting with many other cell polarity factors.•Epithelia is an ideal model system for studying the Par complex function.

Apical–basal polarity is the basic organizing principle of epithelial cells, and endows epithelial cells to function as defensive barriers and as mediators of vectorial transport of nutrients in and out of organisms. Apical–basal polarity is controlled by a number of conserved polarity factors that regulate cytoskeletal organizations, asymmetric distributions of cellular components, and directional transports across cells. Polarity factors often occupy specific membrane regions in response to the adhesion forces generated by cell–cell and cell–extracellular matrix interactions. Both internal polarity factors and the external extracellular matrices play fundamental roles in epithelial cell polarity establishment and maintenance. This review focuses on recent developments of the Par3/Par6/aPKC complex and its interacting proteins in epithelial cell polarity.