Desmosomes and Adherens Junctions

Desmosomes and adherens junctions are the principal anchoring junctions that hold cells together mechanically. Both are built on cadherin adhesion proteins, but they couple to different cytoskeletal systems: adherens junctions link to the actin filament network, while desmosomes anchor the intermediate filaments, together giving tissues the strength to resist stretching and shear.

Definition

Adherens junctions and desmosomes are anchoring cell junctions in which cadherin-family adhesion proteins bind cells together and, through cytoplasmic plaque proteins, connect to the cytoskeleton: classical cadherins and catenins link adherens junctions to actin filaments, while desmosomal cadherins and plakins link desmosomes to intermediate filaments.

Scope

This topic covers the two cadherin-based anchoring junctions—the adherens junction (zonula adherens) and the desmosome (macula adherens)—including their adhesion proteins, the cytoplasmic plaque proteins that connect them to the cytoskeleton, and their contrasting links to actin versus intermediate filaments. It is treated as a reference and educational entry rather than clinical guidance.

Key concepts

• Anchoring junctions
• Adherens junction (zonula adherens)
• Desmosome (macula adherens)
• Classical cadherins and catenins
• Desmosomal cadherins (desmogleins, desmocollins)
• Plaque proteins (plakoglobin, plakophilin, desmoplakin)
• Actin filament versus intermediate filament anchorage

Mechanisms

Both junctions use calcium-dependent cadherins whose extracellular domains mediate adhesion between cells and whose cytoplasmic tails recruit plaque proteins that link to the cytoskeleton. In the adherens junction, classical cadherins (such as E-cadherin) bind beta-catenin and p120-catenin, and through alpha-catenin connect to the actin filament network, forming a continuous adhesion belt near the apical pole. In the desmosome, desmosomal cadherins (desmogleins and desmocollins) engage plaque proteins—plakoglobin, plakophilin, and desmoplakin—that anchor intermediate filaments, producing spot-like rivets that distribute mechanical stress across the tissue. This division of labour means adherens junctions and desmosomes complement one another, the former contractile and dynamic, the latter providing robust, load-bearing attachment.

Clinical relevance

Because desmosomes and adherens junctions provide the mechanical cohesion of epithelia and cardiac muscle, their components are studied in the context of tissue integrity. This entry presents structure and mechanism for reference and education and is not a basis for diagnosis or treatment.

History

Desmosomes and the intermediate (adherens) junction were defined morphologically by Farquhar and Palade (1963) as distinct elements of the epithelial junctional complex. Identification of the cadherins by Takeichi and colleagues and the dissection of the catenin and plaque-protein machinery later established both junctions as cadherin-based adhesion systems differing mainly in their cytoskeletal partners.

Key figures

• Masatoshi Takeichi
• Barry Gumbiner
• William Weis
• Andrew Kowalczyk
• Marilyn Farquhar

Seminal works

• farquhar-palade-1963
• yap-1997
• meng-takeichi-2009
• delva-2009

Frequently asked questions

How do desmosomes differ from adherens junctions?

Both are cadherin-based anchoring junctions, but adherens junctions connect to the actin filament network and often form a continuous belt, whereas desmosomes use specialised desmosomal cadherins and plaque proteins to anchor intermediate filaments at spot-like sites.

What role does calcium play in these junctions?

The cadherins that mediate adhesion in both junctions are calcium-dependent; calcium binding rigidifies their extracellular domains and is required for them to bind partner cadherins on neighbouring cells.