Post Translational Modifications, protein Targetting And Collagen Biosynthesis Flashcards

1
Q

How many helixes are on collagen

A

3
Every third amino acid would be glycine
Also large amount is Serine and proline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where are the hydrogen bonds and why would then be there

A

Within the helix structure
Would allow increased stability in the molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What would be needed for hydroxylation

A

Vitamins c

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does hydroxylation help with

A

Thermostability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the two terminals that’s would be found within the procollagen

A

N terminal
C terminal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What terminal would have the disulfide bonds

A

The C terminal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What causes scurvy and what are some of the symptoms

A

Deficiency of vitamin c or ascortic acid
Weakness, poor healing, gum disease, anaemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is osteogenesis imperfecta

A

The mutation in the COL1A1 or COL1A2 genes
Would have glycine substituted for a bulkier amino acid
Not having the correct folding of the molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is elders-Danlos syndrome

A

Stretchy skin
Mutation in the collagen type V or deficiency in the Lysyl oxidase enzymes (not allowing the cores bridges to form)
Would effect the extra cellular cleavage, the cross link formation and stability would be effected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the steps that would allow the formation of the cross bridges

A

Lysine residues
Lysyl oxidase and oxygen forming the aldehyde derivatives
Formation of the Aldo’s cross links (thought to be spontaneous)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What cleaves the terminals on pro-collagen to form tropocollagen

A

Collagen peptidase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is needed for collagen to enter the endoplasmic reticulum

A

The signalling function that would soon be cleaved off (signal pepsidase)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What stages would occur I the extracellular

A

Cleavage of the n and c terminals to for tropocollagen
The formation of the cross bridges

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How would preproinsulin go to proinsulin

A

Cleavage of the signalling function
Formation of the disulfide bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How would proinsulin go to insulin

A

The cleavage of the C-terminal in the Golgi apparatus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What enzyme is used for the formation of the disulfide bonds

A

Protein disulphide isomerase

17
Q

How can the formation of the disulphide bonds be seen as a redox reaction

A

At first the substrate would be reduced (contains H+) the enzyme would be oxidised.
When the bond formed the substrate would be oxidised as would lose H+ but the enzyme would be reduced as would gain the H+ from the substrate

18
Q

What happens when a protein is misfolded and why

A

Move to the cytosol and would be degraded
If not would build, making it toxic
Damage of the ER

19
Q

How would proteins move into the cells from free ribosomes

A

Signalling element on amino acids (SKL- serine, lysine, leucine)
Attaches to the receptor PTSIR (cytosolic protein receptor)
Would attach to the protein tetramer
Move it to the membrane receptor protein (pex14p)
PTSIR and the tetramer would then move through the membrane
Complex released and the PTSIR moves out (by atp hydrolysis)
Reused

20
Q

How would proteins enter the ER across the membrane

A

The ribosome would attach to the SRPs (signal receptor proteins) these are GTPS
Attaches to another SRP on the membrane
The ribosome soon released (GTP GOES TO GDP AND PI)
This allows the translocon to open
Signal function cleaved off (signal peptidase)

21
Q

What would change if a protein was being made FOR the membrane

A

Added a signal anchor transfer sequence

22
Q

What is O-linked glycosylation

A

Sugar would be added to the OH group of serine of Theronine

23
Q

What is N-linked glycosylation

A

The sugar would be added to the amino acid (asparagine)

24
Q

What are the four things required for protein sorting

A

Signalling function
Receptor
Translocation machinery
The energy (ATP)

25
What re the functions of the endoplasmic reticulum
Hydroxylation Glycosylation Proper folding of the protein Insertion of the protein into the membrane Protein cleavage
26
What can cause protein misfolding
Mutation Protein incorrectly associated with a subunit Protein can also get stuck in its misfolded form
27
What are the functions of the chaperones
Monitor the misfolding Increase transcription of the chaperones Decrease translation of the protein Retain the misfolded protein on the ER
28
What is the difference between the Cis face and the Trans face of the Golgi
Cis face is the side closest to the ER and the nucleus Trans face is the side that is the closest to the membrane of the cell
29
How would the level of C terminal cleaved be different in diabetics
Would be low Diabetics would not produce their own insulin So would not have a lot of the cleaving of the C terminal
30
What is the difference between PEX14 and PTS1R
Both would be used for the transport of a protein into the membrane PEX14 would be the receptor on the perioxisome PTS1R would be the complex that would recognise the signalling sequence (SKL in the case of catalase) and carry the protein through the membrane
31
What protein does the SKL (serine leucine lysine) sequence refer too
Catalase
32
Why is important glycosylation
Protein stability Protein folding Deficiency in N-linked (one the amine of asparagine) would lead to inherited diseases (congenital disorders or glycosylation) Allows interaction with other proteins
33
Where does N-linked glycosylation happen
In the ER
34
Where does O-linked glycosylation happen
In the golgi
35
What amino acids normally undergo hydroxylation
Lysine and proline (in the ER) Can form proline hydroxylase