Collagen Synthesis

Question 1

In collagen, what are the X and Y amino acids most often?

Answer 1

Proline- X

Hydroxylisine/Hydroxyproline- Y

Question 2

How many alpha chains are present in collagen?

Answer 2

3

Question 3

What formation of chains does collagen form?

Answer 3

Triple helix

Question 4

In collagen, which is every 3rd amino acid?

Answer 4

Glycine

Question 5

Which types of collagen, out of I, II, III, form fibrils and which form fibres?

Answer 5

All 3 form fibrils

Only type I and II form fibres

Question 6

Characteristics of type I collagen and where it’s found

Answer 6

High tensile strength

Bone, skin, tendons, BV’s

Question 7

Characteristics of type II collagen and where it’s found

Answer 7

Cartilagenous
Don’t form fibres
Forms elastic and hyaline cartilage

Question 8

Name and characteristics of type III collagen and where it’s found

Answer 8

Reticullin
Forms fibres
Skin, BV’s, lymphatic system

Question 9

What is the name of collagen when it is initially synthesised?

Answer 9

Preprocollagen

Question 10

Where is collagen precursor synthesised and secreted from?

Answer 10

Fibroblasts

Question 11

Is the signal sequence on collagen precursor cleaved or retained? If so by what?

Answer 11

Cleaved

Signal peptidase

Question 12

After cleavage of signal peptide, what is collagen precursor chains called?

Answer 12

Pro α Chains

Question 13

Why is it important that the collagen chains are hydroxylated?

Answer 13

More OH- groups
TF more H bonds form
TF stronger structure

Question 14

What modifications occur to collagen in the RER? (In brief)

Answer 14

Hydroxylation (of selected proline + lysine)
Addition of Galactose
N-linked glycosylation

Question 15

Where does O linked glycosylation of collagen occur?

Answer 15

Golgi body

Question 16

What is the final thing that happens to collagen in RER, before exocytosis?

Answer 16

Chains align and disulphide bonds form

Forms a triple helix

Question 17

What is N-linked glycosylation?

Answer 17

Where a sugar (glucose) is linked onto a chain by forming a bond with the nitrogen in the sugar ring

Question 18

What is O-linked glycosylation?

Answer 18

Where sugar (glucose) is added to chain by forming a bond with the oxygen present in the sugar

Question 19

Which residues in collagen α chains are selectively hydroxylated? What are they then called?

Answer 19

Proline- Hydroxyproline

Lysine- hydroxylysine

Question 20

What enzyme catalyses hydroxylation in collagen synthesis?

Answer 20

Prolyl hydroxylase

Question 21

Which enzyme catalyses the formation of covalent cross link between collagen fibrils?

Answer 21

Lysyl Oxidase

Question 22

What co-factors are required for the enzyme that catalyses hydroxylation of collagen residues? Name the enzyme too

Answer 22

Prolyl hydroxylase
Vitamin C
Fe2+ ions

Question 23

What is the general/basic structure of alpha collagen chains?

Answer 23

Glycine-X-Y

Question 24

What is tropocollagen?

Answer 24

Collagen FIBRILS that have had their N&C terminal propeptides removed?

Question 25

Once finished in the Golgi, what happens to procollagen?

Answer 25

Transported out of Golgi by transport vesicle N&C terminal peptides removed To form tropocollagen Collagen FIBRILS aggregate to form FIBRES Lysyl oxidase catalyses formation of covalent bonds

Question 26

Which residues are selectively N-linked glycosylated and have galactose added to?

Answer 26

Hydrolysine | Proline

Question 27

Which enzyme catalyses the removal of N&C terminal propeptides?

Answer 27

Procollagen peptidase

Question 28

What modification to collagen occurs in the Golgi?

Answer 28

O-linked glycosylation

Question 29

Once tropocollagen has formed, what happens?

Answer 29

Lysyl oxidase catalyses formation of covalent cross links between collagen FIBRILS to form collagen FIBRES

Question 30

Which enzyme catalyses the formation of covalent cross links between collagen fibrils forming collagen fibres?

Answer 30

Lysyl oxidase

Question 31

What does CHANDPORC stand for?

Answer 31

Cleavage, hydroxylation, addition of galactose, n-linked glycosylation, disulphide bond formation, procollagen, o-linked glycosylation, removal of N + C propeptides chains, covalent bond formation