Ask a Teacher

Search



A SHORT NOTE ABOUT TIGHT JUNCTION?
Tight junctions are multiprotein complexes that mediate cell-cell adhesion and regulate transportation through the extra-cellular matrix. Tight Junctions form the closest contact between adjacent cells known in nature. Found in the apical region around the cell's circumference.
Because tight junctions encircle the cell and attach it tightly to its neighbors, these junctions act as a barrier preventing molecules from diffusing across an epithelial sheet between adjacent cells. When situations occur where molecules need get through the layer their transport is a multi-step process, involving several signal pathways, regulation of junction proteins, and alternations in cytoskeletal organization. Tight junctions are a major regulator of permeability, expressing different levels of "tightness" based on location and chemical stimuli. The 'looser' the connection, the greater the variety of molecules that can get across the epithelial sheet.

Transmembrane proteins of the tight junctions are responsive to glycoprotein immunoglobin G (IgG) from cells and to surface antigens on bacteria. Binding of these molecules act as chemical stimuli regulating the tightness of the connections. Recognizing these particular molecules is important becauseof the role signaling plays in the secondary immune response.


comments powered by Disqus