title: Fractionation of the epithelial apical junctional complex: reassessment of protein distributions in different substructures.
abstract: The epithelial apical junctional complex (AJC) is an important regulator of cell structure and function. The AJC is compartmentalized into substructures comprising the tight and adherens junctions, and other membrane complexes containing the membrane proteins nectin, junctional adhesion molecule, and crumbs. In addition, many peripheral membrane proteins localize to the AJC. Studies of isolated proteins indicate a complex map of potential binding partners in which there is extensive overlap in the interactions between proteins in different AJC substructures. As an alternative to a direct search for specific protein-protein interactions, we sought to separate membrane substructures of the AJC in iodixanol density gradients and define their protein constituents. Results show that the AJC can be fractured into membrane substructures that contain specific membrane and peripheral membrane proteins. The composition of each substructure reveals a more limited overlap in common proteins than predicted from the inventory of potential interactions; some of the overlapping proteins may be involved in stepwise recruitment and assembly of AJC substructures.
authors.affiliation: Department of Molecular and Cellular Physiology, Beckman Center for Molecular and Genetic Medicine, Stanford University School of Medicine, Stanford, CA 94305-5435, USA.
authors.forename: Roger
authors.initials: R
authors.lastname: Vogelmann
authors.forename: W James
authors.initials: WJ
authors.lastname: Nelson
mesh_terms: D000818:Animals; D019921:Biotinylation; D015153:Blotting, Western; D002448:Cell Adhesion; D002451:Cell Compartmentation; D002458:Cell Fractionation; D002460:Cell Line; D016764:Cell Polarity; D002499:Centrifugation, Density Gradient; D003287:Contrast Media / Q000494:pharmacology; D004058:Diffusion; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D004847:Epithelial Cells / Q000737:chemistry* / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D018613:Microscopy, Confocal; D011485:Protein Binding; D011506:Proteins / Q000032:analysis* / Q000378:metabolism; D013347:Subcellular Fractions; D019108:Tight Junctions / Q000737:chemistry* / Q000378:metabolism*; D014283:Triiodobenzoic Acids / Q000494:pharmacology
chemical_list: D003287:Contrast Media; D011506:Proteins; D014283:Triiodobenzoic Acids; C044834:iodixanol