The Investigation of cis- and trans-Interactions Between Claudins

OVERVIEW Claudins control the paracellular permeability of the tight junctions in epithelial and endothelial cells forming single cell layers. Several claudins may constitute a network of strands, establishing a continuous barrier within the intercellular clefts of the monolayer. Depending on the claudin composition of a given tissue, the intracellular space may be tight for any solute or permeable for compounds of different molecular weight or differently charged ions. These functions are largely based on intermolecular claudin claudin interactions. Strand formation between claudins requires two components: a longitudinal association along the plasma membrane of the cell-cis-interaction-and an interplay from one cell surface to the next one-trans-interaction. This chapter is aimed at reviewing methods for the analysis of cis- and trans-interacting claudins.