title: Claudin clusters as determinants of epithelial barrier function.
abstract: Claudins are tetraspan tight junction proteins which have been attributed to primarily determine epithelial barrier function in a wide variety of different organs and tissues. Among this protein family with currently 27 members, single claudins contribute in an organ- and tissue-specific manner to defined properties such as cation-, anion- or water-selective pore functions, sealing functions or ambiguous functions. As the size of tight junction strand particles visualized by freeze-fracture electron microscopy have a diameter of approximately 10 nm, multimeric assembly of tight junction proteins appears to be a basic principle for barrier formation. Moreover, expression patterns of different tissues showed that single claudins appear to specifically co-localize with other claudins, which indicates a cluster formation within tight junction strand particles with a fixed stoichiometry. This review provides a critical view on the current understanding of tight junction protein co-localization within strands. We analyze how tissue specific differences of claudin functions could be dependent on their specific partners for barrier formation. Furthermore, a model of claudin clusters as structural and functional units within tight junction strands is provided.
authors: Department of General Physiology, St. Petersburg State University, St. Petersburg, Russia.
authors: Alexander G
authors: AG
authors: Markov
authors: Jörg R
authors: JR
authors: Aschenbach
authors: Salah
authors: S
authors: Amasheh
mesh_terms: D000818:Animals; D057167:Claudins / Q000737:chemistry / Q000502:physiology*; D004848:Epithelium / Q000502:physiology*; D005614:Freeze Fracturing; D006801:Humans; D008854:Microscopy, Electron; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000502:physiology*; D019108:Tight Junctions / Q000502:physiology*
chemical_list: D057167:Claudins; D046912:Multiprotein Complexes
keywords: membrane proteins; protein expression; protein function