1. Tight Junctions Occluding junctions
Sealing strands are rows of transmembrane proteins

2. Transcellular Transport
Essential for segregating transport proteins

3. Anchoring Junctions
Attach cytoskeleton to neighboring cell or to extracellular matrix
Intracellular anchor proteins
Transmembrane adhesion proteins

4. Adherens Junctions Connect actin filaments in neighboring cells
Cadherin transmembrane adhesion proteins
Catenin anchor proteins

5. Desmosomes Connect intermediate filaments in neighboring cells
Cadherin transmembrane adhesion proteins
Complex of anchoring proteins
Pemphigus autoimmune disease

6. Focal Adhesions Connect actin filaments to extracellular matrix
Integrin transmembrane adhesion proteins
Various anchor proteins

7. Hemidesmosomes Connect intermediate filaments to basal lamina
Integrin transmembrane adhesion proteins
Plectin anchor protein

8. Types Of Anchoring Junctions
Junction Transmembrane Extracellular Cytoskeletal Intracellular
Adhesion Protein Attachment Attachment Anchor
Protein
Cell-Cell
Adherens cadherins cadherin actin filaments catenins
Junction (E-cadherin) (a- and b-)
Desmosome cadherins cadherin intermediate catenins,
(desmoglein, desmocollin) filaments desmoplakin
Cell-Matirx
Focal integrins extracellular actin filaments talin, vinculin,
adhesion matrix proteins others
Hemi- integrin a6b4 extracellular intermediate plectin
desmosome matrix proteins filaments

9. Gap Junctions Communicating junctions
Channels composed of connexin transmembrane proteins

10. Junctional Complex
Same relative positions of three junctions in most epithelium

11. Glycosaminoglycans
Unbranched polysaccharide chain with repeating disaccharide unit
Large volume, high negative charge result in gel-like form

12. Hyaluronan
Simple GAG
Not usually linked to protein

13. Proteoglycans Most GAGs covalently attached to protein
Synthesized in Golgi apparatus
Link tetrasaccharide added to serine; other sugars added one at a time

14. Diversity Of Proteoglycans
Extensive variation in types and number of GAG chains

15. Collagens Triple helix from three collagen a chains
Rich in proline and glycine
Proline- ring, stabilizes helix
Glycine- small, tight chain packing
Multiple a chains associate in different combinations

16. Synthesis of Collagens
Synthesized as pro-a-chain precursors
Cleavage of pro-peptides following secretion
Self-assembly into fibrils and aggregation into fibers

18. Hydroxylation In Collagen
Certain lysine and proline residues
Form interchain hyrodrogen bonds
Requires vitamin C; deficiency results in easy bruising, petechiae, scurvy

19. Cross-Linking Of Collagen
Occurs between lysine residues of separate molecules to strengthen fibrils

20. Genetic Diseases Affecting Collagen
Affected
Disease Collagen Mutant Phenotype
Osteogenesis imperfecta I weak bones, fractures
Chondrodysplasias II cartilage deficiency
Ehlers-Danlos syndrome III fragile skin & blood vessels, loose joints

21. Elastin Elastin molecules are cross-linked
Molecules in network expand and contract

22. Fibronectin
Multiple binding sites for extracellular matrix and cell surface molecules

23. Laminin Component of basal lamina
Composed of a, b, and g chains that form distinct isoforms

24. Basal Lamina
Sheet-like networks of laminin and type IV collagen