ECM Flashcards
what is scurvy?
lack of vitamin C (cofactor for hydroxylases)
unstable PROcollagen
tender skin, vessels, tendons.
What is fibrosis?
excessive deposition of type 1 & 3 collagen by fibroblasts.
loss of oxygen exchange in lung due to decreased mechanical response.
outline the structure of laminin.
X shaped trimer glycop of 3 polypeptides (alpha, beta, gamma)
short arms bind one another –> sheet.
Outline the structure of insoluble fibronectin.
FN dimers cross linked by disulphide bonds
at CELL SURFACE when integrins link FN to actin cytoskeleton
Linkage –> tension, exposing FN binding sites.
what is the role of plasma FN?
How are FN levels linked to tumours?
clusters platelets & recruits fibroblasts to assemble new matrix close to wound site.
increased levels linked to apoptosis resistance, + invasion.
outline the synthesis of collagen.
in ER lumen undergoes post translational modification (hydroxylation of Lys & Pro residues –> stable helix formation)
3 proto alpha chains form soluble procollagen
Golgi - oligosaccharides added
Outside - peptidases remove loose ends
lysyl oxidase acts on lys & OHlys to produce fibrils.
lateral interactions of alpha helices –> fibrils.
what are th functions of GAGs?
trap cations & water so resist compression
occupy space
link collagen fibres to form network
combine with calcium hydroxyapatite in bones
What is structure of Elastin?
Alternating segments along pp chain of hydrophobic regions, &alpha helical segments (cross-linked to adjacent molecules by covalent Lys residues)
each segment encoded by different exon.
Describe the structure of MMPs…
common domain = pro-peptide, C-terminal linked to catalytic domain by flexible hinge region
pro-peptide has conserved cys which interacts with zinc in active site, preventing substrate binding –> cleaved for active form!!
how do the basal and reticular lamina differ?
nearest epithelia, composed of laminin & collagen IV
nearest CT, connects basal lamina to it.
