intercellular junction

Intercellular Junction

Presented By:

14-Arid-2067

14-Arid-2030

14-Arid-2070

Presented To:

Dr. Riaz Hussain Pasha

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.

CONT…

There are three main types:

• Gap junction (nexus).

• Tight junction (zonula occludens)

• Anchoring junction

-Desmosome (macula adherens)

-Hemidesmosome

-Adheren (zonula adherens)

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.

Cont…

• Helps in signal transfer in brain.

• Their size vary in different cells.

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.

Cont…

• It prevent mobility of transmembrane proteins.

• It regulate the movement of water and solutes

between epithelial layer.

• Lines the gastrointestinal tract.

Anchoring Junction:

• Cells within tissues anchor to one another and

to extracellular fluid.

• There are following three types:

1. Desmosomes Junction

2. Hemidesmosomes Junction

3. Adherens Juntion

Cont..

Junction Cytoskeletal

Anchor

Transmembrane

Linker

Ties cell to

Desmosomes Intermediate

Filaments

Cadherin Cell

Hemidesmosome Intermediate

Filaments

Integrins ECF

Adherens

Junction

Actin Filaments Cadherin/Integri

ns

Cell/ECF

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.

Cont…

• The gap b/w this junction is 30nm

• Found in epidermis of skin and muscle tissues.

• Blistering diseases.

• Pemphigus.

• Hailey-Hailey disease.

Hemidesmosomes:

• Connect cell to extracellular fluid.

• Connect epithelial cells to basement

membrane.

• Integrins are the linking proteins.

• Present in epidermis of skin.

• Epidermolysis bullosa.

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.