Tissues 6: Extracellular matrix biology II Flashcards
Name some examples of Multi-adhesive glycoproteins
Fibronectin, Fibrinogen Laminins (basement membrane)
Name some examples of proteoglycans
Aggrecan, Versican, Decorin Perlecan (basement membrane)
What are laminins made up of? (What type of chains)
Consist of three chains, one each of an alpha, beta and gamma chain, forming a cross-shaped molecule add pic
Name diseases associated with mutations in genes coding for laminins
Specific chain mutations associated with inherited diseases such as muscular dystrophy and epidermolysis bullosa
Why are there no known mutations in genes that code for fibronectins?
No known mutations in humans - essential for life
Name some important roles for fibronectins
Important roles in regulating cell adhesion and migration in embryogenesis and tissue repair Also important for wound healing (promote blood clotting)
How is fibronectin linked with actin
Fibronectin forms a mechanical continuum with the actin of many cell types. Integrin receptors at the cell surface bind to fibronectin on the outside of the cell, and are linked to the actin cytoskeleton inside the cell. add pic
What is the function of integrins
Integrins are proteins that function mechanically, by attaching the cell cytoskeleton to the extracellular matrix (ECM),
What are Proteoglycans
Core protein to which one or more glycosaminoglycan chains are covalently attached. add pic
What are Glycosaminoglycans (GAG) chain
Glycosaminoglycans are long, unbranched sugars consisting of repeating disaccharides. GAGs occupy a huge volume relative to their mass. These hydrated gels can be very resistant to compression.
Draw the structure of fibronectin
add pic
What substance is cartalige rich in?
Rich in the proteoglycan aggrecan
Cartilage acts as a shock absorber What role does aggrecan play in the shock absorbing property of cartilage?
The GAGs (e.g. chondroitin sulfate) of aggrecan are highly sulfated. Also present are large numbers of carboxyl groups. These multiple negative charges attract cations such as Na+ that are osmotically active. Large quantities of water are therefore retained by this highly negatively charged environment. Under compressive load, water is given up, but regained once the load is reduced. Therefore, aggrecan in the cartilage matrix is perfectly suited to resist compressive forces.
Why does osteoporosis usually occur with older age?
With age aggrecan is cleaved by aggrecanases and metalloproteinases. This results in loss of aggrecan fragments to synovial fluid.
What is decerin
a snall proteoglycan
