Extracellular Matrix Biology 2

Question 1

Describe ECM molecules

Answer 1

very large

modular proteins that have many domains and are multifunctional/adhesive

Question 2

What is the structure of laminins?

Answer 2

3 polypeptide chains (alpha, beta and gamma), very large, multi adhesive

Question 3

What is the function of laminins?

Answer 3

interact with cell surface receptors and other basement membrane components, and self associate

Question 4

Describe congenital muscular dystrophy

Answer 4

absence of alpha 2 in laminin 2 causing hypotonia and weakness from birth

Question 5

What are fibronectins?

Answer 5

family of glycoproteins of ECM and body fluids that can exist as an insoluble fibrillar matrix or soluble plasma protein due to alternate splicing

Question 6

What is the structure of fibronectins?

Answer 6

multiadhesive large multi domain molecule

Question 7

What is the function of fibronectins?

Answer 7

regulate cell adhesion and migration in embryogenesis
tissue repair
mechanical continuum with actin cytoskeleton
promotes blood clotting

Question 8

What is the structure of proteoglycans?

Answer 8

core protein with 1+ glycosaminoglycan chains are covalently attached

Question 9

How are GAGs related to their function?

Answer 9

large volume compared to mass so hydrated gels are resistant to compression

Question 10

What are the families of proteoglycans? with examples

Answer 10

basement membrane e.g. perlecan
aggregating (interact with hyaluronan) e.g. aggrecan
small leucine rich e.g. decorin
cell surface e.g. syndecan

Question 11

What is the structure on GAG chains?

Answer 11

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

Question 12

What are the 4 groups of GAG chains? with examples

Answer 12

hyaluronan
chondroitin sulfate and dermatan sulfate e.g. decorin
heparan sulfate e.g. syndecan
keratan sulfate

Question 13

What is the hyaluronan structure?

Answer 13

simple carb chain not attached to core protein, unsulfated

Question 14

Where is hyaluronan synthesised?

Answer 14

cell surface

Question 15

What does decorin do?

Answer 15

binds to collagen fibers for fiber formation

makes sure collagen fibres of similar diameter

Question 16

Define cartilage matrix

Answer 16

filaments of proteoglycan network with embedded collagen fibrils

Question 17

Where is rich in aggrecan?

Answer 17

hyaline cartilage that cushions the end of long bones

Question 18

What is the function of aggrecan? how does this happen?

Answer 18

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

Question 19

What is specific to the structure of aggrecan?

Answer 19

large number of sulphated and carboxylated GAGs creating negative charge

Question 20

What is osteoarthritis?

Answer 20

loss of ECM in joints so loss of cartilage and bones rub