Cell adhesion molecules (CAMs) are proteins located on the cell surface that help cells stick to each other and their surroundings. CAMs are classified into five major families: cadherins, Ig superfamily, selectins, integrins, and mucins. Cadherins are calcium-dependent molecules that form desmosomes and exhibit homophilic adhesion. Integrins are heterodimeric proteins that participate in cell-cell adhesion and binding of cells to the extracellular matrix. Malfunctions in CAMs can lead to diseases like breast cancer and leukocyte adhesion deficiency syndrome.

1. MBBS, MPHIL BIOCHEMISTRY, CHPE, Pgt of
PhD BIOCHEMISTRY

5. ⦁ Cell adhesion molecules (CAMs) are glycoproteins
located on the cell surface. These proteins are typically
trans membrane receptors and are composed of three
domains:
⦁ intracellular domain......with cytoskeleton
⦁ trans membrane domain...with CAMs
⦁ extracellular domain...with extracellular matrix
⦁ CAMs are involved in binding with other cells or with
the extracellular matrix (ECM).
⦁ It help the cells to stick to each other and to their
surroundings.

6. ⦁ Cell adhesion receptors enable cells to recognize and
bind molecules on other cells or in the extracellular
matrix.
⦁ Cell adhesion receptors can form
⦁ Homophilic (or homotypic) adhesions – between same
type of molecules( Cadherin – cadherin)
⦁ Heterophilic (or heterotypic) adhesions –between
different type of molecules(Selectins – mucins)

7. Most of the cell adhesion molecules belong to five major
protein families:
 Cadherins
IgSuper family
 Selctins
 Integrins
 Mucins

8. ⦁ The cadherins are calcium-dependent adhesion
molecules plays important role in cell adhesion by
forming desmosomes.
⦁ Sub classes
 Neural (N)-Cadherin
 Placental(P)- Cadherin
 Epithelial(E)-Cadherin
• They exhibit homophilic adhesion.
• The failure of cadherin
mediated cell-cell adhesion
cascade in breast cancer.
.

9. ⦁ The Ig superfamily
CAMs are calcium-
independent trans
membrane
glycoproteins.
⦁
• It function by both
homophilic and
heterophilic binding
• Involved in recognition,
binding or adhesion
processes of cells.

10. ◦ Intracellular adhesion molecule 1(ICAM1; CD54)
◦ Intercellular adhesion molecule 2 (ICAM2),
◦ Vascular cell adhesion molecule1 (VCAM1;
CD106),
◦ Platelet endothelial cell adhesion molecule 1
(PECAM 1; CD31)
 All possess an extracellular region known as
immunoglobulin domains.

11. • The selectins are a family of
divalent cation dependent
glycoproteins.
•They are carbohydrate-binding
proteins.
⦁ Members includes:
Endothelial (E)-selectin
Leukocyte (L)-selectin
Platelet (P)-selectin
• It plays an important role in
many host defense
mechanisms.

12. Integrins are a diverse and large group of
heterodimeric glycoproteins.
alpha and beta..
both participate in
binding.
 Eight sub families..
β1 through β8.
• Integrins participate in cell-cell adhesion
• In binding and interactions of cells with
components of the extracellular matrix such as
fibronectin.

14.  1) In 'outside–in' signaling, Integrins behave
like signaling receptors. Binding of Ligands
changes the conformation of the integrin and
contributes to integrin clustering. This leads to
intracellular signals that control cell polarity,
cytoskeleton structure, gene expression and
cell survival and proliferation.

15.  In 'inside–out' signaling, an intracellular
activator, such as talin, binds to the β-integrin
tail, leading to conformational changes that
result in integrin activation.
 Inside–out signaling controls adhesion
strength and enables sufficiently strong
interactions between integrins and extracellular
matrix (ECM) proteins to allow integrins to
transmit the forces required for cell migration
and ECM remodeling and assembly.

16. ⦁The Mucins are the group of
serine and threonine-rich
protein and hydroxyproline
enabling post-translational O-
glycosylation.
⦁Their extended structure allows
them to present as binding site for
selectins

17. Involvement in inflammation
Tumorigenesis
Establishment of the blood-brain
barrier
Involvement in lymphocyte homing
In regulation of apoptosis.

18. ⦁ Special interactions between molecule expressed on the
surface of (receptor) and molecule on the surface of
potential target cells (ligands) are important mechanism in
cell-cell communication. These surface molecules collectively
called cell adhesion molecule.
⦁ They are classified into five major families.
⦁ Despite of their various role, malfunctioning of CAMs leads to
breast cancer, leukocyte adhesion deficiency (LAD)
syndrome , epithelial cell cancer
Summary