PSL 310 Unit 1: Cell-Cell Junctions

Junctional complex

Holds cells together laterally

Apical surface

Faces outside/external environment

Basal surface

Faces tissue/blood, basal faces blood

Three major components of junctional complex

Adhering junction, tight junction, desmosome

Adhering junction

Also called belt junction, actin filaments line inner circumference of cell like a belt, attached to integral membrane proteins that touch each other in the extracellular space

What are the junctions mostly mediated by?

Calcium

Desmosome

Integral mmebrane proteins connected to proteins on inside of cell, intermediate filaments connected to intracellular protein, filaments course throughout the cell, dissipates forces and reduces tearing

What parts of a junctional complex hold cells together?

Adhering junction and desmosomes

Tight junction

Also called occluding junction, prevents things from getting between cells in the intercellular space, prevents things from getting into the tissue/blood

Where are tight junctions located?

Closer to the apical surface, highest up in the gap

Gap junctions

Not part of junctional complex, allow cell to communicate things in cytoplasm between each other like cAMP and calcium

Hemidesmosome

On basal surface, half a desmosome with integral membrane proteins that attach to collagen filaments in extracellular matrix, essentially hold down cells to connective tissue