The complex three-dimensional arrangement of cells in any multicellular organism is defined and maintained by interactions of cells with each other and the extracellular matrix. Cell-cell junctions are specialized structures where the multi-protein complexes on one cell interact with the multi-protein complexes on another  cell. These cell junctions are classified  into three main types based on their function — occluding, anchoring, and gap junctions.
Occluding or Tight Junctions
Tight...

The complex three-dimensional arrangement of cells in any multicellular organism is defined and maintained by interactions of cells with each other and the extracellular matrix. Cell-cell junctions are specialized structures where the multi-protein complexes on one cell interact with the multi-protein complexes on another  cell. These cell junctions are classified  into three main types based on their function — occluding, anchoring, and gap junctions.
Occluding or Tight Junctions
Tight...

Strong contact points between adjacent cells anchor them to each other, forming tissues. Such anchoring junctions are of two types –  adherens junctions and desmosomes. Adherens junctions are abundant in tissues such as  epithelium and endothelium, forming a continuous zone of adhesion called the adhesion belt. In other tissues, such as  heart muscle, they appear as clusters, linking the cells to produce coordinated heart muscle contraction.
Adherens Junctions are Dynamic
The endothelial cells...

Anchoring junctions are multiprotein complexes that help cells connect to other cells and the extracellular matrix. Anchoring junctions are present on the lateral and basal surfaces of cells, providing strong and flexible connections. Focal adhesions are often formed due to cell interactions with the ECM substrata, which initiate signal transduction via kinase cascades and other mechanisms. Together, they provide stability and tissue integrity. There are three types of anchoring junctions:...

Tight junctions are molecular seals between cells that prevent the leaking of fluids, ions, and other small solutes across cavities and compartments in multicellular organisms. They are mainly composed of claudin and occludin transmembrane proteins, and other proteins such as tricellulin and JAM (junctional adhesion molecule). All these proteins are 4-pass transmembrane proteins, except JAM, which is a single-pass transmembrane protein belonging to the immunoglobulin superfamily. The...

Contact-dependent signaling, as the name suggests, requires that communicating cells be in direct contact with each other. This is achieved either through receptor-ligand interactions or by specialized cytoplasmic channels that allow the flow of small molecules between cells. In animal cells, channels called gap junctions facilitate contact-dependent signaling in certain tissues, whereas, plasmodesmata perform a similar function in plants.
Gap Junctions
In animal cells, gap junctions are formed...