title: Epithelial junctions and polarity: complexes and kinases.
abstract: OBJECTIVE
  An enormous body of research has been focused on exploring the mechanisms through which epithelial cells establish their characteristic polarity. It is clear that under normal circumstances cell-cell contacts mediated by the calcium-dependent adhesion proteins of the intercellular adhesion junctions are required to initiate complete polarization. Furthermore, formation of the tight, or occluding, junctions that limit paracellular permeability has long been thought to help to establish polarity by preventing the diffusion of membrane proteins between the two plasmalemmal domains. This review will discuss several selected kinases and protein complexes and highlight their relevance to transporting epithelial cell polarization.
  
  
  RESULTS
  Recent work has shed new light on the roles of junctional complexes in establishing and maintaining epithelial cell polarity. In addition, work from several laboratories suggests that the formation of these junctions is tied to processes that regulate cellular energy metabolism.
  
  
  CONCLUSIONS
  Junctional complexes and energy sensing kinases constitute a novel class of machinery whose capacity to generate and modulate epithelial cell polarity is likely to have wide ranging and important physiological ramifications.
authors.affiliation: Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06525-8026, USA. Michael.caplan@yale.edu
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Caplan
authors.forename: Patricia
authors.initials: P
authors.lastname: Seo-Mayer
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000502:physiology; D000818:Animals; D016764:Cell Polarity / Q000502:physiology*; D004847:Epithelial Cells / Q000502:physiology*; D006801:Humans; D007365:Intercellular Junctions / Q000502:physiology*; D046912:Multiprotein Complexes / Q000502:physiology*; D010770:Phosphotransferases / Q000502:physiology*; D019108:Tight Junctions / Q000502:physiology
chemical_list: D046912:Multiprotein Complexes; D010770:Phosphotransferases; D055372:AMP-Activated Protein Kinases