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Specifications

Clone Host Grade Applications Polyclonal Rabbit Purified E B IF

Tight junctions are specialized regions of cell-cell contact that are particularly abundant in luminal epithelial cell sheets. 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 are presumed to interact with each other to form a sort of "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 so-called "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. Confinement of, for example, the glucose symport to apical surfaces allows glucose to be transported vectorially from the lumen, through the cell, and into the bloodstream. Several peripheral membrane proteins are associated with tight junctions including ZO-1, ZO-2, ZO-3 (members of membrane-associated guanylate-kinase family), cingulin, the 7H6 antigen, Rab-3b, symplekin. While their precise functions are not known, roles for these proteins have been suggested in tight junction assembly and maintenance; signal transduction; and the regulation of tight junction permeability. Furthermore, 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 kD 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. Fortunately, a closer examination of isolated tight junctions uncovered two related ~22 kD, 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. 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.
Catalog #	C5838-16A
Applications	Suitable for use in ELISA, Western Blot and Immunofluorescence. Other applications have not been tested.
Recommended Dilution	ELISA (Immunogen): 0.1-1ug/ml
	Western Blot (Canine, Human and Rat): 0.5-2ug/ml
	Immunofluorescence (Rat): 1-3ug/ml
	Optimal dilutions to be determined by the researcher.
Storage and Stability	May be stored at 4°C for short-term only. For long-term storage and to avoid repeated freezing and thawing, add sterile glycerol (40-50%), aliquot and store at -20°C. Aliquots are stable for at least 12 months at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer..
CAS Number	N/A
Clone Type	Polyclonal
Isotype	IgG
Host	Rabbit
Source	Rat
Concentration	0.25mg/ml
Form	Supplied as a liquid in PBS, pH 7.4, 0.1% sodium azide.
Purity	Purified by epitope affinity chromatography.
Immunogen	Synthetic peptide derived from the C-terminus of the human Claudin-2 protein.
Specificity	Recognizes rat Claudin 2 protein at ~22kD and does not appear to cross-react with related endogenous proteins. Reactivity was confirmed by Western Blot with rat kidney and by immunostaining of rat small intestine. Species Crossreactivity: human and canine
Important Note	This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications without the expressed written authorization of United States Biological.