This antibody is specific for the 22 kDa Claudin-3 protein. Reactivity has been confirmed with mouse liver and lung homogenates, canine MDCK and human MCF-7 cell lysates by western blotting, and with formalin-fixed, paraffin-embedded (FFPE) human normal colon and colon cancer tissues by immunohistochemistry. For best results in immunohistochemistry with formalin-fixed, paraffin-embedded (FFPE) tissues, heat induced epitope retrieval (HIER) with citrate buffer, pH 6.0, is required prior to staining.
Claudin 1-8 proteins are a family of transmembrane proteins associated with tight junctions. Tight junctions are specialized regions of cell to cell contact; made up of a network of strands to act as a molecular gasket for preventing the leakage of ions, water etc. between cells. They are abundant in luminal epithelial sheets where they maintain epithelial cell polarity. Different tissues exhibit different claudin composition. In freeze-fracture electron micrographs, tight junctions are visualized as belt-like bands of anastomosing sealing strands (TJ strands) that completely encircle the lateral surfaces of each cell. TJ strands on adjacent cells interact with each other to form a ""molecular gasket"" that prevents ions, water and other molecules from leaking between cells and thus, from one side of the sheet to the other. In addition to this ""barrier"" function, the ""fence"" function of tight junctions plays an important role in maintaining epithelial cell-polarity by blocking the diffusion of membrane proteins between apical (luminal) and basolateral cell surfaces. Several peripheral membrane proteins are associated with tight junctions including ZO-1, ZO-2, ZO-3, cingulin, the 7H6 antigen, Rab-3b, and symplekin. Suggested roles for these proteins include involvement in tight junction assembly and maintenance, signal transduction, and the regulation of tight junction permeability. A growing body of evidence suggests that actin filaments play a major role in regulating tight junction permeability. Until recently, the only transmembrane protein known to be associated with tight junctions was occludin, an ~65 kDa protein with four transmembrane domains. Despite widespread expectation, a critical structural role for occludin in TJ strands was ruled out by the observation of apparently normal tight junctions formed between cells disrupted at both occludin alleles. A closer examination of isolated tight junctions uncovered two related ~22 kDa, four-transmembrane domain proteins, claudin-1 and claudin-2, with no similarity to occludin. In contrast to occludin, which induces only a small number of short strands at cell-cell contact sites when introduced into fibroblasts lacking tight junctions, claudin-1 and -2 induce networks of strands characteristic of true tight junctions.8,9 Though inconclusive, these findings suggest that claudin-1 and -2 are major structural components of TJ strands and that occludin plays some other accessory role. Excitement in the tight junction field continues to rise following the recent discovery of claudins -3, -4, -5, -6, -7, and -8 and experiments suggesting that tight junctions in different tissues are comprised of different sets of claudin family proteins.
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Protein Aliases: C7orf1; Claudin-3; Clostridium perfringens enterotoxin receptor 2; CPE-R 2; CPE-R2; CPE-receptor 2; CPETR2; HRVP1; integral membrane protein claudin-3; Rat ventral prostate.1 protein homolog; ventral prostate.1 protein homolog; ventral prostate.1-like protein
Gene Aliases: AI182374; C7orf1; CLDN3; CPE-R2; CPETR2; HRVP1; mRVP1; RVP1