Long description

This diagram shows a small section of epithelial tissue and the location and schematic structure of the different junction types. The tight junction holds the cells very close together via their lateral surfaces, and is situated very near the apical end of the cells. The adherens junction is present on the lateral surface further from the apical end, and links the actin filaments of adjacent cells together via membrane-spanning proteins and intracellular proteins that link these to the cytoskeleton. The gap junction, which is also on the lateral surface, holds the cells tightly together: adjacent cells are separated by a narrow gap which is spanned by channel-forming protein. Also shown are the two types of anchoring junction; both of these comprise membrane-spanning adhesion proteins, which link the cells together across the intercellular space, and are linked on their cytosolic side to intermediate filaments of the cytoskeleton. The desmosome links adjacent epithelial cells together via their lateral surfaces; and the hemidesmosome links an epithelial cell to the extracellular matrix via its basal surface.