Extracellular Matrix Biology 2 Flashcards
Describe ECM molecules
very large
modular proteins that have many domains and are multifunctional/adhesive
What is the structure of laminins?
3 polypeptide chains (alpha, beta and gamma), very large, multi adhesive
What is the function of laminins?
interact with cell surface receptors and other basement membrane components, and self associate
Describe congenital muscular dystrophy
absence of alpha 2 in laminin 2 causing hypotonia and weakness from birth
What are fibronectins?
family of glycoproteins of ECM and body fluids that can exist as an insoluble fibrillar matrix or soluble plasma protein due to alternate splicing
What is the structure of fibronectins?
multiadhesive large multi domain molecule
What is the function of fibronectins?
regulate cell adhesion and migration in embryogenesis
tissue repair
mechanical continuum with actin cytoskeleton
promotes blood clotting
What is the structure of proteoglycans?
core protein with 1+ glycosaminoglycan chains are covalently attached
How are GAGs related to their function?
large volume compared to mass so hydrated gels are resistant to compression
What are the families of proteoglycans? with examples
basement membrane e.g. perlecan
aggregating (interact with hyaluronan) e.g. aggrecan
small leucine rich e.g. decorin
cell surface e.g. syndecan
What is the structure on GAG chains?
long unbranched sugar with repeating disaccharides, one of the 2 sugars is always an amino sugar
some are slated of carboxylated to increase negative charge
What are the 4 groups of GAG chains? with examples
hyaluronan
chondroitin sulfate and dermatan sulfate e.g. decorin
heparan sulfate e.g. syndecan
keratan sulfate
What is the hyaluronan structure?
simple carb chain not attached to core protein, unsulfated
Where is hyaluronan synthesised?
cell surface
What does decorin do?
binds to collagen fibers for fiber formation
makes sure collagen fibres of similar diameter
Define cartilage matrix
filaments of proteoglycan network with embedded collagen fibrils
Where is rich in aggrecan?
hyaline cartilage that cushions the end of long bones
What is the function of aggrecan? how does this happen?
resist compressive forces attract cations that as osmotically active due to negative charge
this causes a large amount of water to be retained
under compression water is lost and regained once pressure reduced
What is specific to the structure of aggrecan?
large number of sulphated and carboxylated GAGs creating negative charge
What is osteoarthritis?
loss of ECM in joints so loss of cartilage and bones rub
