extracellular matrix Flashcards
collagens: explain the biosynthesis of collagen, summarise the structural and functional post-translational modifications, explain assembly and recall functions
fibrillar collagen location
abundant in bone, tendon and skin
fibrillar collagen properties
fibrous, inelastic, high tensile strength
how do fibrillar collagens exhibit high tensile strength
staggered array; successive layers formed ar right angles so resist force in all directions
structure of fibrillar collagen
3 a chains in a left-handed stiff triple helix: glycine (small)-x (proline)-y (hydroxyproline)
type I a chain structure
2 same chain, 1 different chain
type II and III a chain structure
all same a chain
a chain to collagen fibre
IC: a chain → triple helix → EC: collagen fibril → collagen fibre
fibrillar collagen biosynthesis: precursor, location, process
synthesised from procollagen in endoplasmic reticulum by hydroxylation
process of fibrillar collagen biosynthesis
procollagen (N and C-terminal propeptides not present in triple helices) → collagen (N and C-terminals removed EC) → fibrils (cross-linking)
what does hydroxylation contribute to
interchain hydrogen bonding, modifying covalent cross-links
what enzymes catalyse hydroxylation
polyl and lysyl hydroxylases
what prosthetic groups do these enzymes require
vitamin C and Fe2+
consequences of absence of these prosthetic groups
tissue instability leading to scurvy
fibril-associated collagen: type IX and XIII function
regulate fibril organisation and size
fibril-associated collagen: type IV function
forms sheet-like network in basal lamina
