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Cell junctions are large, multi-protein complexes that can link cells to the extracellular matrix forming cell-matrix junctions, or act as contact points between neighboring cells in tissues to form cell-cell junctions.

Cells typically have three main types of cell-cell junctions - tight, anchoring, and gap junctions, each with a distinct structure and function.

Consider the columnar epithelium. The tight junctions near the apices of these cells hold adjacent plasma membranes together and function as a barrier to the flow of molecules through the intercellular spaces.

Below this apical portion are two types of anchoring junctions— the adherens junctions and desmosomes.

Together, these anchoring junctions form an interconnected cytoskeletal network across cells that helps to resist mechanical forces.

The third type, gap junctions, are dispersed throughout the plasma membrane, particularly towards the basal end. These junctions act as communication channels between adjacent cells, allowing molecules and ions to pass through.