Tight junction
From Biocrawler, the free encyclopedia.
Tight junctions are joints between cells in an epithelium. They do 3 things:
- Hold cells together
- Separate apical membranes and basolateral membranes
- Prevent the movement of solutes and water between cells
They are formed by connexin proteins, joining the cytoskeletons of the adjacant cells. Epithelia are classed as 'tight' or 'leaky' depending on the ability of the tight junctions to prevent water and solute movement: tight epithelia have tight junctions that prevent most movement between cells, leaky epithelia do not.
An example of a tight epithelium is the distal convoluted tubule, part of the nephron in the kidney. An example of a leaky epithelium is the proximal convoluted tubule.
