Protein Post-translational Modification

Question 1

Which pathway of protein secretion is not regulated and is an ongoing process?

Answer 1

Constitutive edge collagen from fibroblasts or albumin from hepatocytes

Question 2

What’s the most abundant protein in the body?

Answer 2

Collagen 25-35 % of protein in the body

Question 3

Where is collagen commonly found?

Answer 3

Connective tissue extracellular matrix

Question 4

What is the basic unit of collagen

Answer 4

Tropcollagen which is 3 polypetides 1000 amino acids long in a right handed triple helix. Each peptide is an alpha chain with a glycine every third amino acid.

Question 5

Why is glycine so important?

Answer 5

Small r group so fits in the middle of the triple helix

Question 6

Other than glycerine what other amino acids are common in collagen?

Answer 6

Proline and hysdroxyproline

Question 7

What stabilises the structure of tropcollagen?

Answer 7

H bonds between alpha chains

Question 8

What type of collagen is most abundant?

Answer 8

Type I

Question 9

Type 1 collagen consist of which alpha chains?

Answer 9

Two alpha 1 chains and an aplha 2 chain

Question 10

Where is type I collagen found..

Answer 10

Skin
Tendons and ligaments
Bone

Question 11

Where do you find type II collagen?

Answer 11

Cartilage and intervertebral discs

Question 12

Type IV collagen is found where?

Answer 12

In the basement membrane

Question 13

What type of collagen is in the cardiovascular system?

Answer 13

Type III

Question 14

Why don’t we make collagen in the cell? Why must Procollagen be secreted?

Answer 14

Collagen is way too big

Question 15

Where is a lot of the alpha chain modification of collagen done?

Answer 15

The ER

Question 16

What’s the first step in collagen post translational modification?

Answer 16

Signal peptide cleaved

Question 17

What happens to the lysine and proline residues in the ER.

Answer 17

Hydroxyl action

Question 18

Vitamin c is required for intracellular manufacture of Procollagen, how?

Answer 18

Lyvuitamin C and Fe2+ are needed to hydroxyl ate proline. With out this hydrogen bonding stabilising the triple helix is not possible.

Question 19

Does the triple helix span the entire Procollagen molecule?

Answer 19

No the c and n terminus have some amino acids not involved in forming helices

Question 20

Does procollagen contain disulphide binds?

Answer 20

Yes in the no helical regions

Question 21

How is collagen secreted?

Answer 21

Exocytosis

Question 22

Is collagen a protein with. Sugars attached or not?

Answer 22

I linked glycosilation

Question 23

What is cleaved outside the cell on Procollagen?

Answer 23

N and c termini

Question 24

List ten nomenclature given to the molecule for collagen during modification.

Answer 24

Pre procollagen
Procollagen
Tropcollagen
Collagen

Question 25

How so a collagen fibre made?

Answer 25

Tropical laden covalently bond

Question 26

Why does collagen show banding Histological,y?

Answer 26

Gaps between tropcollagennor mid fibre section

Question 27

What is the cross ,ink between tropcollagennor?

Answer 27

A Aldo’s cross link from two lysine residues which were oxidised to make aldehydes
Derivatives to react with one another

Question 28

What enzyme helps bind tropcollagen and what does it need to function

Answer 28

Vitamin B6 and Cu++ in the extracellular spence

Question 29

Why is Procollagen cleaved to tropcollagennor outside the cell?

Answer 29

Peptidase for n and termini outside cell

Question 30

Is the predicted length of collagen from its genre the same as the final molecule

Answer 30

No lots is cleaved off and the. To make a fibre lost of peptides are combined