L23 - The extracellular matrix Flashcards
What are the features of the extracellular matrix?
Regulates:
- migration
- Tissue Integrity and cell shape
- Proliferation
- Differentiation
Is an extracellular meshwork of proteins and hydrated macromolecules.
Describe the structure of collagen (Fibrous protein ECM type).
Collagen has…
~20-40 variants
- Glycine-proline hydroxyproline triplet repeats
- Triple helix with 3 alpha chains
- ## Produced by fibroblasts and epithelial cells
What happens if there is a collagen defect from ECM mutation?
Ehlers-danlos syndrome:
Vascular form & Arterial rupture
Describe the structure of Elastin (a fibrous protein). and fibrillar which is essential for the formation of elastin fibres.
Fibrillar - elastin is laid down over a microfibril scaffold of fibrillin.
What is the mutation if there is a defect in elastin/fibrillin?
Marfans syndrome: which affects bones and eyes and aortic rupture.
Describe the structure of GAGS, Glysoaminoglycans.
They are a disaccharide chain, 70-200 units long and highly charged.
Proteoglycan have 95% sugar and 80 saccharides.
Glycoproteins have 60% sugar and 15 saccharides.
What are the two ECM types of adhesion proteins?
Fibronectin and Lamin.
What is the role of integrins?
They facilitate ECM adhesion as they bind matrix through divalent cations.
Removal of cations causes cells to detach
What are focal adhesion components?
They are transmembrane receptor that provide a connection to cytoskeleton. Used in signalling.
Explain the effects of the integral related defects of aB3-integrin and B2-integrin.
aB3-intergin:
- Platelets bind fibrinogen to form mesh and clot blood.
- Causes Glanzmann’s thrombasthenia
- Leads to bleeding gums and nose bleeds.
B2-integrin:
- Leukocyte Adhesion Deficiency (LAD) syndrome
- Impaired expression
- Recurrent bacterial infections.
What are the two types of fibrous proteins and what do they do?
Collagen and elastin which provide structural integrity.
