Extracellular Matrix (Reynolds)

Question 1

ECM contains many structural ____ and _____.

Answer 1

proteins

proteoglycans

Question 2

proteins in the ECM include

Answer 2

collagens fibers
elastin
fibronectin

Question 3

_______ are high highly charged protein/saccharide polymers which prevent compression on ECM

Answer 3

proteoglycans

Question 4

Which of the GAGs will never form a proteoglycan because it lacks a protein core and sulfate group?

Answer 4

hyaluronic acid, longest of the GAGs

Question 5

Collagen is made from a triple helix structure called?

Answer 5

Tropocollagen

Question 6

the sequence of collagen includes Gly-X-Y, where X is ___ and Y is ___.

Answer 6

X- proline

Y- hydroxyproline

Question 7

collagen can be categorized into two classes of ___ and non____.

Answer 7

fibrillar and non fibrillar

Question 8

what is the main function of the basement membrane? and what types of collagen is it made from?

Answer 8

mainly prevents migration of cells between tissues, made from type 4 and 7

Question 9

Collagen synthesis starts as _____, which migrates via signal sequence to the ______.

When the signal sequence is removed, it forms?

Answer 9

preprocollagen, migrates to the ER

Procollagen

Question 10

Overall collagen synthesis:

Answer 10

Preprocollagen (w/ signal sequence) to ER –>

procollagen (with signal sequence removed) –>

tropocollagen (when disulfide
linkages occur) –>

mature collagen.

Question 11

Scurvy is linked to defects in collagen synthesis because of a lack of?

Answer 11

vitamin C, b/c its a cofactor for producing hydroxyproline

Question 12

a defect in collagen synthesis with Type 1 collagen can lead to?

Answer 12

osteogensis imprefect (brittle bone disease)

Question 13

What protein is primarily responsible for the stretchy nature of vessels, lungs, ligaments and skin.

Answer 13

elastin!

Question 14

Elastin monomers forms 2D structures called

Answer 14

desmosines.

Question 15

what protein acts as a attachment point for other cellular and ECM components?

Answer 15

fibronectin

Question 16

What are the gel-forming portion of the ECM?

Answer 16

proteoglycans!

Question 17

a defect in the degradation of proteoglycans is called?

Answer 17

mucopolysaccharidosis,

affecting lysosomes

Question 18

multiple proteoglycans can interact to produce a large macromolecular structure called/

Answer 18

aggrecans , often have collagen and other cells embedded within

Question 19

what is the function of proteoglycans?

Answer 19

gives rigidity/flexibility/compressibility to ECM

allows tissues to withstand torsion/ shock

they have very large negative charges, which causes h2o to flow into ECM, causing swelling/stiffness of ECM

Question 20

What proteins are responsible for digesting structural components of the ECM?

(remodeling of ECM)

Answer 20

Matrix metalloproteases! (MMPs)

very specific, can degrade collagen, elastin, fibronectin, protein core of proteoglycans…

Question 21

A deficiency in ___ will impair Matrix Metalloprotease function.

Answer 21

Zinc! zinc is involved with protelytic activity

Question 22

to activate a zymogen MMP, what must be removed?

Answer 22

propeptide domain, contains a cysteine switch.

When propeptide domain is still attached to MMP, cysteine switch binds to Zinc=inactive

Question 23

Defects in Enamelysin or MMP-20 are implicated in the disease?

Answer 23

amelogenesis imprefect

enamel is thin, weak, discolored

Question 24

What are the two main proteins that signal cells to release MMPs to remodel the ECM?

Answer 24

• integrin receptors

- cytokine and growth factors

Question 25

___ are thought to be involved in inflammatory processes in body. They signal cells to secret MMPs for ECM remodeling.

Answer 25

cytokines .