Question 1
Question
Physical modifications are reversible
Question 2
Question
Give an example of protein oxidation
Question 3
Question
Where are proteins with oxidated modifications are nearly universally found where?
Question 4
Question
What is so useful about disulphide bonds?
Question 5
Question
Where do oxidation reactions occur?
Answer
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The golgi
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The ER
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The ribosome
Question 6
Question
Disulphide bonds assist in recovery from denaturation
Question 7
Question
In Maristoylation, what is added?
Answer
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Maristic acid
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Maristoylate
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Maristoyl-3-phosphate
Question 8
Question
Describe the substrate added in Myristoylation
Question 9
Question
What is the point of Myristoylation?
Question 10
Question
What sequence is the Myristoylation substrated added to?
Answer
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The N-terminus
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The C-terminus
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MGXXX(T/S)
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MPXXX(G/F)
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SDXXX(S/R)
Question 11
Question
The protein that performs Myristoylation is N-Myristoyl transferase
Question 12
Question
How is the Myristoylation substrate added?
Answer
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First the phenylalinine is removed
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First the methionine is removed
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First the tyrosine is removed
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Then the substrate is added to the glycine
-
Then the substrate is added to the leucine
-
Then the substrate is added to the isoleucine
Question 13
Question
Prenylation is the addition of ketones
Question 14
Question
Name the two substrates most often added in prenylation
Answer
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Farnesyl
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Geranylgeranyl
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Derisyl
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Nitrosyl
Question 15
Question
Where does prenylation occur?
Answer
-
In a CAAX box (where A should be Alanine, but anything small and hydrophobic will do)
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In a FAAX box (where A should be Isoleucine, but anything small and hydrophobic will do)
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In a CAAT box (where A should be Alanine, but anything small and hydrophobic will do)
Question 16
Question
In prenylation, the X of the sequence must be the terminal aa of the chain
Question 17
Question
Put the following in order
A- The COOH group is modified to a methyl group to make it uncharged
B- The substrate is added to the cystine
C- The last three aa are removed
Question 18
Question
Prenylation is done to proteins destined for the cytoplasm
Question 19
Question
Name the types of glycosylation
Answer
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N-linked
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O-linked
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C-Mannosylation
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Phosphoserine Linked
Question 20
Question
Glycosylation is the addition of carbohydrate chains
Question 21
Question
What is the site of N-linked glycosylation?
Answer
-
The Asn in an NX(S/T)
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The Phe in an FX(S/T)
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The Gly in a GX(S/T)
Question 22
Question
What is the residue that is attached to the amino acid?
Answer
-
Mannose
-
Glucose
-
N-acetyl-galactosamine
-
N-acetyl glucosamine
Question 23
Question
What residues are on the tips of the branches?
Question 24
Question
If the branches end with mannose, what is the process called?
Question 25
Question
Why are 3 glucose added to the sugar complex in the golgi?
Answer
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So they can be removed as markers for protein folding and transport
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So the Golgi knows they're bound for the membrane
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So the Golgi can degrade the protein as faulty
Question 26
Question
Why is it called High-Mannose Biantennary N-Glycosylation?
Answer
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Because one of the three branches is removed, giving two 'antenna'
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Because another branch is formed off the first one, giving two 'antenna'
-
Because proteins with this type of glycosylation act as receptor proteins with two antenna
Question 27
Question
Once the Biantennary complex has been formed, what happens next?
Answer
-
Mannose is removed
-
Addition of N-acetyl neuraminic acids
-
Addition of glucose
-
Removal of N-acetyl glucosamine
-
Addition of a fucose to the GlcNac bound to the amino acid
Question 28
Question
Why the complicated process of adding and removing sugars?
Answer
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It adds a date stamp to the cell- over time the NeuAc's fall off, which signals the protein for degredation
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It adds a transport signal- depending on what is added or removed, proteins are directed to different areas by carrier proteins
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It's quality control- the contortions required to add and remove all the sugars mean that the protein has folded properly
Question 29
Question
The HIV virus can use glycosylation to hide from the immune system
Question 30
Question
Why is N-linked glycosylation potentially dangerous?
Answer
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Because the immune system is programmed to ignore it, viral coat proteins can use it to hide the virus
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Because NeuAc's can be toxic in high concentrations
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Because the removal of mannose can cause the protein to misfold
Question 31
Question
HIV1-gp120 has many N-X-(T/S) sequences to be glycosylated
Question 32
Question
Where does HIV1-gp120 bind?
Answer
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CD4 receptor
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CD8 receptor
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B-lymphocyte receptors
Question 33
Question
How does the HIV virus invade the lyphocyte?
Answer
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It's only glycosylated on a very small binding site
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It's only not glycosylated on a very small binding site
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Which allows it to bind and invade