Which junction type is primarily linked to intermediate filaments in epithelial cells?

• A. Tight junctions
• B. Adherens junctions
• C. Gap junctions
• D. Desmosomes

Answer: (D)

Desmosomes anchor intermediate filaments to neighboring cells, giving epithelial tissue its mechanical strength. In epithelia, keratins (a type of intermediate filament) are linked across cells by desmosomes, whose cadherins (desmoglein and desmocollin) connect to plaque proteins like desmoplakin that attach to the intermediate filaments. This arrangement resists pulling and stretching, which is crucial for maintaining tissue integrity in areas subject to stress.

Tight junctions sit at the very top of the cell surface and seal gaps between cells, with connections to actin filaments. Adherens junctions connect to the actin cytoskeleton through E-cadherin and catenins, forming belts that help maintain cell–cell junction stability. Gap junctions create channels for direct intercellular communication via connexins, not for anchoring intermediate filaments.