Collagen

Question 1

What are the 4 types of collagen and where are they found?

Answer 1

Be (So Totally) Cool, Read Books

Type I
Bone, Skin, Tendon

Type II
Cartilage

Type III
Reticulin

Type IV
Basement membrane

Question 2

Briefly outline the 6 stages of collagen synthesis

Answer 2

1. Synthesis
   - Preprocollagen alpha chain translation (Gly-X-Y)
2. Hydroxylation
   - Of proline & lysine residues (needs Vit C)
3. Glycosylation
   - Of pro-alpha-chain hydroxylysine residues
   - Formation of procollagen (triple helix 3x alpha chains)
   - H and disulfide bonds
   - Problems forming helix = osteogenesis imperfecta
4. Exocytosis
   - Of procollagen
5. Proteolytic processing
   - Cleavage of disulfide rich terminals
   - Becomes Tropocollagen
   - Problems cleaving = Ehlers-Danlos Syndrome
6. Cross-Linking
   - Covalent cross-linking of tropocollagen molecules
   - Stabilised by lysyl oxidase
   - Collagen fibres formed