INTERCELLULAR CONNECTION-TIGHT JUNCTION

SUMMARY

1. Junctions that tie cells together and endow tissue with strength & stability.

2. Types: zonula occludens (tight junction), zonula adherens, desmosome, hemi-desmosome & focal adhesions (attach cells to their basal laminas).

3. Characteristically surround the apical margins of cells in epithelia, e.g. intestinal mucosa, walls of renal tubules.

4. 3 main families of transmembrane proteins: occludin, junctional adhesion molecules (JAM), claudins; and several proteins that interact from the cytosolic side.

5. Restrict molecular movement across the epithelium & prevents the movement of proteins in the plane of the membrane.

6. Tight junctions permit the passage of some ions & solutes between adjacent cells (paracellular pathway), the degree of leakiness depending on their protein makeup.

Reference(s)

Barrett, K.E., Barman, S.M., Brooks, H.L., X, J. and Ganong, W.F. (2019). Ganong’s review of medical physiology. 26th ed. New York: Mcgraw-Hill Education