Differentiate the types of occluding junctions.
Tight junctions are only found in vertebrates, while septate junctions are mainly found in invertebrates.
Name the three types of cell junctions.
Occluding junctions, anchoring junctions and communicating junctions.
A single epithelial cell has tight junctions, but also carrier proteins on both sides. Name and localize them.
Na+ driven glucose symports would be located on the microvilli on the lumen of the gut. Near the basolateral surface are passive glucose carrier proteins.
What are the two types of tight junctions proteins? Describe the tight junctions structure.
Claudins and occludins. Tight junctions allow anchorage to the actin filaments through ZO proteins (zonula occludens).
Each occludin & claudin are arranged in identical ways (N & C termini in the cytosol, 4 TM regions & thus 2 extracellular loops).
Claudin gene mutations can cause specific diseases. True or False?
True.
Describe anchoring junctions.
Allows cell-cell & cell-matrix adhesion.
For actin filaments: cell-cell = adherens; cell-matrix = focal adhesions.
For intermediate filaments: cell-cell = desmosomes; cell-matrix = hemidesmosomes.
