Structure

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• A collagen molecule is a protein with a repeating amino acid sequence (Gly-X-Y)_n.
  • The first amino acid of this triplet is glycine (collagen is comprised of ⅓ glycine).
  • Position X: most commonly proline (also common: lysine, hydroxylysine)
  • Position Y: most commonly hydroxyproline (also common: hydroxylysine, lysine)

Types

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See Osteogenesis imperfecta

Tip

• Compare with ligaments, which are made of elastin.
• Ligaments attach bone to bone, and tendons attach muscle to bone.
• Connect presence of elastin with Marfan syndrome
  • FBN1 can disrupt the normal regulation of TGF-β → Tall stature
  • Skin → Skin hyperextensibility
  • Large arteries → aortic dilation, aneurysms, or dissection
  • Elastic ligaments → Joint hypermobility
  • Lung → Increased risk of spontaneous pneumothorax

Deficient in vascular type of Ehlers-Danlos syndrome (threE D).

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See Goodpasture syndrome