CELL ADHESIONS (1).pptx BSc Botany

2.  INTRODUCTION
 TYPES OF CELL ADHESION MOLECULES (CAMS)
 MAJOR FAMILIES OF CELL ADHESION MOLECULES (CAM)
I. Integrin
II. Cadherin
III. Selectin
IV. Immunoglobin superfamily CAM’s
 CELL JUNCTIONS
I. Gap junction
II. Tight junction
III. Desmosomes
IV. Hemidesmosomes
V. adherens
 CONCLUSION
 REFRENCE

3. ADHESION Refers to “STICKINESS”
CELL ADHESION – HOW CELLS STICK TO ONE ANOTHER
 Cell-cell
 Cell-extracellular matrix
Cell adhesion is the ability of a single cell to stick to another cell or an
extracellular matrix (ECM). Cell adhesion molecules are proteins that help
in cell adhesion.

4. If the cell adhesion molecules
between two neighboring cells
are the identical.
(Cadherin-Cadherin)
If the cell adhesion molecules
between two neighboring cell
are not identical.
(Selectin-Mucin)
If the cell adhesion molecules
between two neighboring cell
requires an extracellular linker
molecule.

5. These cell adhesion molecules
can be divided into 4 major
families:
1. Integrin
2. Selectin
3. Cadherin superfamily
4. Immunoglobin superfamily

10. THERE ARE THREE MAIN
TYPES:
 Tight junction (zonula occludens)
 Gap junction
 Anchoring junction
i. Desmosome (macula adherens)
ii. Hemidesmosome
iii. Adheren (zonula adherens)

12.  It like a tunnel between two neighboring cells
 It allows water and ions flow between this gap tunnels.
 Consist of six connexon proteins arranged to form a doughnut shape structure.
 A gap junction located in neurons referred to as an electrical synapse are important in
neurotransmitter release
 E.G: Cardiac Muscle cells, Neurons, smooth muscle

13.  Also known as Zona Occludens.
 It connects two cells together like a glue.
 Prevent leakage of fluid.
 It regulate the movement of water and solutes between epithelial layer
 The borders of two cells are fused together, often around the whole perimeter of each cell, forming a continuous
belt..
 E.g.: Urinary Bladder, Intestine and kidney

14.  Known as Maculae adherens.
 Form cell to cell junction.
 Intracellular adaptor proteins connect to intermediate filament and form cytoplasmic plaque.
 Cadherin joins the cytoplasmic plaques of two cells.
 The cell adhesion proteins of the desmosome, desmoglein and desmocollin, are members of the cadherin family.
 On the cytoplasmic side of the plasma membrane, there are two dense structures
• The Outer Dense Plaque - where the cytoplasmic domains of the cadherins attach to desmoplakin via
plakoglobin and plakophillin.
• The Inner Dense Plaque - where desmoplakin attaches to the intermediate filaments of the cell.

15.  Connect cell to extracellular fluid.
 Hemidesmosomes look like half-desmosomes that attach cells to the underlying basal lamina.
 Rather than using desmogleins, hemidesmosomes use desmopenetrin cell adhesion proteins,which are members of
Integrin family.
 The integrin molecule attach to one of many multi-adhesive proteins such as laminin, resident within the extracellular
matrix, thereby forming one of many potential adhesions between cell and matrix.

16.  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.

17.  CELL ADHESION – HOW CELLS STICK TO ONE ANOTHER
 cell interaction is of 2 types
 Cell-cell
 Cell-extracellular matrix
 Cam molecules help in cell adhesion
 Types of cell adhesion molecules
 Homophylic
 Heterophylic
 Through extra cellular matrix
 Families of cam molecules
 Integrin
 Cadherin superfamily
 Selectin
 Immunoglobin superfamily
 Cell junctions- sites where cell adhesions take place
 Types of cell junctions
 Tight junction (zonula occludens)
 Gap junction
 Anchoring junction
 -Desmosome (macula adherens)
 -Hemidesmosome
 -Adheren (zonula adherens)