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Name and describe the constituents of ECM
- fibers
- collagen fibers add tensile strength elastic fibers add elasticity reticular fibers “rigid” framework
- ground substance
- withstand compression glycosaminoglycans (GAGs) proteoglycans adhesive glycoproteins
tissue fluid maintains hydration
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Describe Collagen Fibers
many different types (≈29)
most fibrillar, some amorphous (non-fibrillar)
- type I most common -
- * tough, inelastic fiber add tensile strength to CT
- *»20% of total body protein
- * stronger than steel
* reticular fibers actually type III collagen add strength to stromal elements
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What is the molecular formula, native polymer, and tissue distribution for Type 1 Collagen?
note a = alpha
[a1(l)]2a2
- skin, tendon, bone, dentin, fascia
- (high tensile strength- 90% of total body collagen)
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What is the molecular formula, native polymer, and tissue distribution for Type 2 Collagen
[a1(II)]3
cartilage, nucleus pulposus, notochord, vitreous body, cornea
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What is the molecular formula, native polymer, and tissue distribution for Type 3 Collagen
[a1(Ill)]3
- skin, uterus, blood vessels,
- reticular fibers, spleen, lymph nodes
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What is the molecular formula, native polymer, and tissue distribution for Type 4Collagen
[a1(IV)]3
basal lamina of epithelial cells, kidney glomeruli, lens capsule, etc.
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What is the molecular formula, native polymer, and tissue distribution for Type 5Collagen
[a1(VII)]3
small fibers(67 nm)
anchoring fibrils in basal laminae
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Describe formation and composition of Type 1
formed by packing of tropocollagen molecules into collagen fibrils
triple helix structurecomposed of:
a1 procollagen - 2 chains
a2 procollagen - 1 chain
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List events in collagen type 1 intracellular production
- 1. transcription of message in nucleus
- 2. translation of message (on RER)
- 3. synthesis of preprocollagen w registration peptides
- 4. cleavage of signal proteins (in RER)
- 5. hydroxylation of proline and lysine(in RER)
- 6. glycosylation of hydroxylated lysines (in RER)
- 7. formation of procollagen into secretory vesicles
- 8. movement into transfer vesicle
- 9. packaging of procollagen into secretory vessicles
- 10. transport to plasma membrane (cytoskeletal elements)
- 11. exocytosis of helical procollagen
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List sequence of extracellular events in collagen synthesis
- 11. exocytosis of helical procollagen (depends on text)
- 12. Cleavage of non-helical registration proteins to form tropocollagen.
- 13. polymerization of tropocollagen into collagen fibrils
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