Junctions

belts that encircle the cells near the apical surface of the junctional complex

Contain adherens, whose extracellular sections overlap with the extracellular sections of cadherins on adjacent membranes

Calcium-dependent (due to cadherin overlap)

Associated with actin

the cytoplasmic domains of cadherin will interact with catenins and thus the actin of the cytoskeleton

• Forms continuous sheets
• Located at the very apical end of the junctional complex between adjacent epithelial cells
• Make contact at intermittent points
• -          contain integral proteins that run mostly parallel to one another and to the membrane and form continuous fibrils that completely encircle the cell
• made of both occluding and claudin, which are present together within the linear fibrils

• Sites between animal cells that come very close to one another without making direct contact
• The cleft between cells is spanned by very fine strands that are actually molecular pipelines that pass through adjoining plasma membrane and open into the cytoplasm of the other cell
• Composed of an integral membrane protein called connexin, which can organize itself into connexons, which has six connexins arranged in a ring around the annulus
• Tightly connected through noncovalent interactions

• Disc-shaped that contain cadherins with a different domain structure from those in adherens junctions
• -          To distinguish them, they are called demogleins and desmocollins
• Dense cytoplasmic plaque on the inner surface with intermediate filaments linked to the cytoplasmic domain of desmosomal cadherins by more proteins
• Calcium-dependent

• Dense plaque on the inner surface of plasma membrane with keratin-containing (intermediate filaments) extending out toward the cytoplasm
• Consists of the protein keratin, which serve a supportive function
• keratin filaments are linked to the ECM by membrane-spanning integrins, which transmit signals from the ECM

• Binds cells to its neighbor through connection of cadherins in the extracellular portions near the apical surface
• Cells held by calcium-dependent linkages
• Connect the external environment to the actin cytoskeleton
• Provides a pathway for signals

• Regulates passage
• Impermeability to water
• Blood brain barrier
• Binds cells into continuous sheets
• Transmits signals
• Fences to maintain the polarized character of epithelial cells by blocking diffusion of integral proteins
• Involved in signaling pathways

• Connect cytoplasm
• Intercellular communication
• Nonselective but can be gated and respond to voltage or cytosolic calcium ion concentration
• Involved in stimulation of cardiac and smooth muscle
• Allow cells to cooperate metabolically by sharing key metabolites and coenzymes

• Link cells across an extracellular gap
• Its plaques serve as anchorage for looping intermediate filaments
• Structural continuity and tensile strength

• Anchors the basal layer to the underlying basement membrane
• Transmits signals

near the apical surface of cells

epithelial cells

animal cells

in cells under mechanical stress, such as the cervix

inner surface of the plasma membrane