Explain the relationship between ECM and the connective tissue
-Complex network of proteins and carbohydrates filling spaces between cells >Connective tissue is rich in ECM
Describe the different forms of connective tissue
>Collagen (I,II,III,IV) - tensile strength >Multi-adhesive glycoproteins (fibronectin, fibrinogen, laminins) >Proteoglycans (Aggrecan, decorin, perlecan) Basement membrane = collagen IV + laminin
Explain the assembly and recall the function of collagen
Most abundant protein (at least 28 types) Major protein in skin, tendons and bones Allows the resistance of tensile force Produced by fibroblasts
Summarise the structural and functional post-translational modifications of collagen
-3 alpha chains in a helical structure -every 3rd position is glycine, no room for other side chain residues -successive layers perpendicular to each other (resist tensile force in all directions) -In skin, mature bone and cornea
Explain the biosynthesis of collagen
- 3 alpha chains come together to form procollagen, undergo covalent modifications (triple-helical pro-callagen) = secreted
- Extracellular peptidase remove propeptides (N + C), produce left handed fibrillar collagen
- molecules for lateral bonds to create fibrils
- Lysine and hydroxylysine are modified when forming covalent cross-linkages
Describe the structure of laminins
Explain how abnormalities in the ECM can result in disorders
Osteoarthritis
- erosive disease = degradation of ECM
- absorbant properties of cartilage is lost
- aggrecan cleaved by aggrecanases and metalloproteinase
- lost in synovial fluid
Explain the significance of modifieed amino acids within collagen
- Hydroxyl group contributes to the interchain H bond formation
- lysine + hydroxylysine = modified in covalent cross linkages
- require vit C and Iron
- Tensile and stability
Recall the function and composition of elastic fibres
-Core protein of elastin and microfibrils rich infibrillin
