Intercellular junction

1. Intercellular Junction Presented By: 14-Arid-2067 14-Arid-2030 14-Arid-2070 Presented To: Dr. Riaz Hussain Pasha

2. Intercellular junctions A  cell junction is a type of structure that exists within the tissue of some multicellular organisms. specializations of the cellular margins that contribute to the adhesion or allow for communication between cells. Mostly found in epithelial tissues.

3. CONT… There are three main types: Gap junction (nexus). Tight junction (zonula occludens) Anchoring junction -Desmosome (macula adherens) -Hemidesmosome -Adheren (zonula adherens)

4. Gap Junction: It is a communicating junction. Gap junctions  consist of intercellular channels in the plasma membrane of adjacent cells. Consist of six connexon proteins arranged to form a doughnut shape structure. Play role in cardiac muscle contraction.

5. Cont… Helps in signal transfer in brain. Their size vary in different cells.

6. Tight Junction: The borders of two cells are fused together, often around the whole perimeter of each cell, forming a continuous belt like junction known as a tight junction or zonula occludens (zonula = latin for belt).  ZO-1 & ZO-2 Link transmembrane proteins (Occludin and Clauding) with Spectrin. Prevent leakage of fluid. Found in the apical region around the cell's circumference.

7. Cont… It prevent mobility of transmembrane proteins. It regulate the movement of water and solutes between epithelial layer. Lines the gastrointestinal tract.

8. Anchoring Junction: Cells within tissues anchor to one another and to extracellular fluid. There are following three types: Desmosomes Junction Hemidesmosomes Junction Adherens Juntion

9. Cont.. Junction Cytoskeletal Anchor Transmembrane Linker Ties cell to Desmosomes Intermediate Filaments Cadherin Cell Hemidesmosome Intermediate Filaments Integrins ECF Adherens Junction Actin Filaments Cadherin/Integrins Cell/ECF

10. Desmosomes: Form cell to cell junction. Known as Maculae adherens. Intracellular adaptor proteins connect to intermediate filament and form cytoplasmic plaque. Cadherin joins the cytoplasmic plaques of two cells.

11. Cont… The gap b/w this junction is 30nm Found in epidermis of skin and muscle tissues. Blistering diseases. Pemphigus. Hailey-Hailey disease.

12. Hemidesmosomes: Connect cell to extracellular fluid. Connect epithelial cells to basement membrane. Integrins are the linking proteins. Present in epidermis of skin. Epidermolysis bullosa.

13. Adheren Junction: Junctions which form junction b/w cell to cell. Also known as Zonulae adherens. Lies basal to tight junction. Microfilaments of two cells are connected by cadherins. Cytoplasmic face is linked to actin cytoskeleton. Actin myosin interaction can change the shape of the epithelium.