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IMS > W2- Lecture 10- Post-translational Modifications Of Proteins > Flashcards

W2- Lecture 10- Post-translational Modifications Of Proteins Flashcards

1
Q

Over what no of amino acids can a poly pep time fold into a defined shape ?

A

40 AA

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2
Q

Primary secondary’s and tertiary structure of proteins

A

1- sequence of aa
2- interaction between aa e.g alpha helixes or beta sheets , loops and coils
3- 3D shape
4 - more then one protein = complex

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3
Q

What direction / terminus do we read

AA form/to ?

A

N terminus to the C terminus

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4
Q

What mutation causes sickle cell disease ?

A

mutation in hba haemoglobin/ beta globin gene sunbsitation from T to A
Glu to val
Side chain changes which causes impact

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5
Q

Where can we find the ionic bonds / electrostatic attraction ?

A

In the r group between

CO2- and NH3+

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6
Q

Where can we find the disulfide bridges ?

A

Between cysteine and SH Groups

Cys-S-S-Cys

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7
Q

What are proproteins?

A

Inactive proteins that need activation before use

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8
Q

Where is the preproinsulin fed from / into ?

A

Ribosomes feed into ER

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9
Q

Name the three steps of post translational modification of proinsulin
+ where

A 
All in ER 
1- Cleavage and removal of signal peptides 
2-Oxidation of SH groups to SS
(disulfide bridge formation )
3- Cleavage and removal of the C chain
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10
Q

Why is post translational mod of proteins important ?

A
  • to allow proteins to have a different spacial arrangement / biological activity
  • allows regulation of proteins
  • Increases protein diversity
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11
Q

Name different PTM

A

Cleavage
isomerism
Addition of Small molecules e.g phosporylation

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12
Q

Describe protein phosphorylation

A

Phosphate group donated by ATP

Catalysed by protein kinase

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13
Q

What enzyme catalysed the back reaction of phosphorylation of a protein ?

A

Phosphatase

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14
Q

Describe how pyruvate dehydrogenase is regulated by phosphorylation/ de phosphorylation

A

phosphorylation/ de phosphorylation is regulated by protein kinase

Activated by high NADH and AcetylCoA

but inhibited by pyruvate

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15
Q

Explain how EGF receptor binds with ligand and how phosphorylation takes place + impact

A
  • when binds to ligand
  • forms firmer
  • phosphorylation each other
  • activates of genes- can lead to excess cell growth
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16
Q

What is the cell cycle dependant on ?

A

Cyclin and cyclin dependant kinases

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17
Q

How do Cyclin and cyclin dependant kinases act to promote the cell cycle

A

CDK and cyclins only work when boundtogether

  • CDKs phosphorylate serine is threonine
  • promotes cycle from moving to the next step in the cycle
  • type of cyclin and concentration drive cell cycle
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18
Q

What are the two most phosphorylated AA?

A

Serine

Threonine (often associated with each other)

19
Q

What does tyrosine phosphorylation cause ?

A

Activation off signalling networks but activator gets protein protein interactions

20
Q

Detecting phosphorylated proteins

A

Phospho-specific antibodies

2d electrophoresis + western blotting

21
Q

describe protein acetylation

A

Acetyl group is donated by acetyl Coenzyme A to a lysine

Catalysed by protein acetyltransferase (PAT)

22
Q

Describe the deacetylation of a protein

A

Catalysed by protein DeACetylase (PDAC)

Where an acetyl group is removed from the amino acid lysine within a protein

23
Q

Where is the primary target for acetylation

A

Histones

24
Q

Describe protein methylation

A

Methyl group donated by S-adenosylmethionie
Catalysed by protein methyl transferase
Majorly arginine and lysine
Not all reversible

25
Q

Describe demetthylation of a protein

A

Methyl group removed
Catalysed by protein demethylase
Majorly arginine and lysine
Not all reversible

26
Q

What is the histone code hypothesis

A

That multiple histone modifications will lead to specific down stream effects

27
Q

Describe a way PTM changing chemical nature of AA

A

Citullination/deimination
Of arginine converting it to citrulline
Positive charge to neutral charge

Immune system attacked citrullinated proteins
Causing autoimmune response and arthritis

28
Q

Explain glycosilation

A

Addition. Of mono/polysaccarides or other proteins
After glycosylation = glycoprotein
Effects folding

29
Q

Name two important AA that are glycosylated for the cell surface structure

A

Asparagine - linked (N)

Or serine/Threonine- linked (o)

30
Q

Where does glycosylation take place

A

N linked ER

O linked in the golgi / cytoplasm

31
Q

Describe n linked glycosylation

A

Polysaccaride added as a 14 sugar subunit to asparagine

In the ER

32
Q

DESCRIBE O linked glycosylation

A

Sugar added one at a time
In golgi (secreted p)/ cytoplasm (cellular p )
Sugar added to hydroxyl group of serine or threonine
Rarely lysine or hydroproline are glycosylated

33
Q

How is the n linked oligosaccrides processed ?

A

Er - removes 3 glucose residues

Golgi - mannose residues removed + other sugars added

34
Q

Protein ubiquination

+aim

A 
Ubiquity attached its glycine to lysine 
Needs 3 enzymes 
Ubiquitous activating enzymes 
Ubiquitous conjugating 
Ubiquitous ligand 
(E1 , E2 , E3)
Marked for degradation in a proteasome 
(regulating proteins )
35
Q

Which enzyme removed ubiquitin from its attachment protein ?

A

Deubiquitinating enzyme (DUBs)

36
Q

Protein control everything - so by controlling it via ubuquitantion

A

You can control e.g synaptic transmission

37
Q

Name 4 types of lipidation

Aka increasing affinity to lipids

A

C-terminal glycosyl phosphatidylin (GPI)anchor
N terminal myristoylation
S-myristoylation
S-prenylation

(These aren’t mutally exclusive )

38
Q

GPCR Regulation via phosphorylation

A

Phosphorylation action on protein which recycles receptor to cell surfaces
or
Can be degraded

39
Q

Name two PTM that modify the amino acids

Reversible ?

A

Deamination
Eliminylation

Irreversible

40
Q

Name 1 PTM that causes cleavage

Reversible?

A

Proteolysis

Irreversible

41
Q

Name 2 PTM that add polypeptides

Reversible ?

A

Ubiquitylation
UBL- protein conjugation

Yes reversible

42
Q

Name 4 PTM that add complex molecules

Reversible ?

A

AMPlyation
ADP-ribosylation
Glycosylation
Isoprenylation

Reversible

43
Q

Name 3 PTM that add chemical groups

Reversible ?

A

Hydroxylation
Phosphorylation
Acetylation
Methylation

Reversible

IMS (74 decks)

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