Cell Junctions and Adhesions
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Transcript of Cell Junctions and Adhesions
CELL JUNCTIONS AND ADHESIONS
AMITHBABU.C.BMScD-ENDO
INTRODUCTION-CELL JUNCTION
What are cell junctions?
What are the three most common types of cell junctions?
INTRODUCTION-CELL JUNCTION
CELL JUNCTIONS
They are classified into 3 main groups1.Tight junctions2.Anchoring junction =adhesion belt , desmosome and hemidesmosome3.Gap junction
CELL JUNCTIONWhat do all adhesive
junctions have in common?
Where are adhesive junctions most commonly found?
Cell Junctions
What distinguishes a tight junction?
Where are tight junctions found?
CELL JUNCTION
What is special about gap junctions?
FUNCTIONAL CLASSIFICATION
Seal cells of an epithelial sheet to create a permeability barrier
Apical vs. Basolateral sortingMolecular Composition Claudin: Transmembrane Occludin: Transmembrane ZO Proteins: Plasma Membrane. Actin cytoskeleton attachment
TIGHT/OCCLUDING JUNCTIONS
(ZONULA OCCLUDENS)
ADHERENS JUNCTIONS
What are adherent junctions
DESMOSOMES
HEMIDESMOSOMES“HALF-DESMOSOMES”
Distribute forces on an epithelium to the basal lamina
Integrins mediate basal lamina adhesionAnchor proteins link integrins to
intermediate filaments via plectin
HEMIDESMOSOMES
De: DesmosomeHD: HemidesmosomeLD: Lamina Densa
GAP JUNCTIONSWhat are gap junctions ?
What are their functions?
COMMUNICATINGGAP JUNCTIONS
GAP JUNCTIONS
CELL ADHESION
What is cell adhesion?
FORMING THE CONNECTIONS BETWEENCELLS
Cell adhesion receptors enable cells to recognize and bind molecules on other cells or in the extracellular matrix
Ligands can be other cell adhesion receptors (receptor receptor contact) or extracellular matrix molecules Make cells stick to other cells or extracellular matrixCell adhesion receptors also activate intracellular
signalling pathways (primarily for cell death/survival but also secretion etc.)
CLASSIFICATION
Integrin familySelectin family Immunoglobulin (Ig) superfamilyCadherin family Mucin-like familyOther adhesion molecules
CELL ADHESIONWhat are the
different categories of adhesion receptors?
What is the difference between homophilic and heterophilic interactions?
CELL ADHESIONWhat characteristics do all CAMs
share?
In what kinds of adhesion events do the CAMs participate?
CELL ADHESION SUMMARY