What are intercellular junctions and why are they important?

Hey,

A cell junction is a type of structure that exists within the tissue of a multicellular organism. They consist of protein complexes and provide contact between neighbouring cells, between a cell and the extracellular matrix, or they build up the paracellular barrier of epithelia and control the paracellular transport.

Plasmodesmata are microscopic channels which go across the cell walls of plant cells, enabling transport of water and minerals and communication between them. These junctions are found only in plants, not animals cells.

Tight junctions are the closely associated areas of two cells whose membranes join together forming a virtually impermeable barrier to fluid. It is a type of junctional complex present only in vertebrates.

Desmosomes are molecular complexes of cell adhesion proteins and linking proteins that attach the cell surface adhesion proteins to intracellular keratin cytoskeletal filaments.

A gap junction is a specialized intercellular connection between a multitude of animal cell-types. It directly connects the cytoplasm of two cells, which allows various molecules and ions to pass freely between cells. This is very similar to plasmodesmata that are found in plants.