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IMS > Post translational modification > Flashcards

Post translational modification Flashcards

1
Q

What does Tertiary Folding result in?

A

Fibrous or Globular Proteins

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2
Q

What are Pro Proteins?

A

Inactive peptides or Proteins that need PTM to activate them

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3
Q

During Insulin Production, what modification takes place during PTM?

A
  1. Cleavage and Removal of signal peptide by signal peptidase in ER
  2. Oxidation of -SH groups to SS ( disulphide bridges) in ER
  3. Cleavage and Removal of C chain in ER
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4
Q

What 2 main types can PTM divide into?

A
  1. Processing ( Proteolytic Cleavage)

2. Covalent Modification ( Chemical post translation)

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5
Q

During Translation, what Covalent modifications would take place to a 20AA peptide that is synthesized?

A

Chemical process would change;

a) Spatial structure
b) Biological activity

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6
Q

Some PTM Proteins are Reversible, What does this result in?

A

Rapid Dynamic regulation of Protein Activity, by controlling balance of Reverse PTM’s

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7
Q

Which Popular PTM Proteins are reversible?

A

Acetylation, Methylation, Phosphorylation

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8
Q

List 3 Biological Processes of PTM proteins Controlling their activities?

A
  1. Metabolism
  2. Cellular Signalling
  3. Gene Transcription
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9
Q

What is PTM a Key Mechanism to Increase? and Why?

A

Proteomic Diversity , Increases Complexity of Proteome

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10
Q

What are the 3 Structural Changes (Classification) of PTM Proteins?

A
  1. Proteolytic Cleavage
  2. Proline Isomerisation
  3. Addition of Small Functional Groups
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11
Q

What is Proteolytic Cleavage?

A

One or Several AA removed from N-Terminus of a Protein. OR Protein Peptide bond Cleaved Internally

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12
Q

What is Proline Isomerisation?

A

Change in Proline Residue Spatial Confirmation (Between Cis and Trans)

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13
Q

List some Examples of Small functional groups in Addition to PTM Proteins?

A

Phosphorylation, Acetylation, Methylation, Hydroxylation

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14
Q

What is Protein Phosphorylation?

A

A Phosphate Group (donated by ATP) is transferred to an Acceptor Protein

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15
Q

What is Protein Phosphorylation Catalyzed by?

A

Protein Kinase

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16
Q

Give a Example of a Reversible Protein Phosphorylation and its Mechanism?

A

Pyruvate Dehydrogenase - Activated by NAD+ and ACh, Inhibited by Pyruvate

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17
Q

What Protein is the Cell cycle Controlled by?

A

Cyclins and their Cyclin Dependant Kinases

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18
Q

What are the 3 most Common Phosphorylated AA’s?

A
  1. Serine
  2. Threonine
  3. Tyrosine
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19
Q

What does the Phosphorylated AA Tyrosine do?

A

Binds specific proteins, promoting Protein:Protein Interactions as part of signalling networks

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20
Q

What 2 Methods can be used to Detect Phosphorylated Proteins?

A
  1. Proteolysis

2. 2D-gel Electrophoresis

21
Q

What is Protein Acetylation?

A

An Acetyl group ( donated by acetyl-CoA) transferred to Acceptor AA lysine

22
Q

What is Protein Acetylation Catalyzed by?

A

Protein AcetylTransferase (PAT)

23
Q

What is the Process of Protein Deacytylation Catalayzed by?

A

Protein DeACetylase (PDAC)

24
Q

What do Protein Acetylation target most?

A

Histones

25
Q

Why is the Reversible Histone Acytelation important?

A

Controls Gene Transcription

26
Q

What is Protein Methylation?

A

A Methyl group (donated by S-adenosylmethionine) is transferred to an Acceptor Protein

27
Q

What is Protein Methylation Catalyzed by?

A

Protein Methyltransferase

28
Q

What is the Process of Protein Methylation Catalyzed by?

A

Protein Demethylase

29
Q

What are the 2 Major AA methylated?

A

Arginine and Lysine

30
Q

What is the best example of Protein Methylation?

A

N-Methylation of arginine and lysine side chains of Histones in Gene Regulation

31
Q

Give an Example of PTM involving changes in Chemical nature of AA?

A

Citrullination of Argenine converting it to Citrulline. The Immune system attacks Citrullinated Proteins which can cause Arthiritis

32
Q

Give an Example of a PTM additional Large Functional Group?

A

Glycosylation, Fatty Acids

33
Q

What is Protein Glycosylation?

A

Process of adding -mono or -poly saccharides to a protein

34
Q

What are Glycosylated Proteins called?

A

Glycoproteins

35
Q

What does Protein Glycosylation, have a significant effect on?

A

Protein Folding, Conformation, Distribution, Stability and Activity

36
Q

What are some Biological Functions of Glycosated Proteins?

A

Protein Stability, Trafficking and Recognition

37
Q

What two kinds of Olygosaccharides are major structural components of cell surface and secreted proteins?

A

Carbohydrates in the form of aspargine linked (N-linked) or serine/threonine linked ( O-linked)

38
Q

What modifications occur to N-linked glycosylation in the ER?

A

Polysaccharide added as a 14 sugar unit to aspargine residue of the new synthesised polypeptide

39
Q

What modifications occur to O-linked glycosylation in the Golgi/Cytoplasm?

A

Sugar added one at a time to hydroxyl group of serine/threonine.
Golgi - secreted proteins
Cytoplasm - cellular proteins

40
Q

What is Protein PolyUbiquitination?

A

Small protein containing 76 AA

41
Q

What is the process of Protein PolyUbiquitination?

A

Last glycine in Ubiquitin attached to lysine in proteins

42
Q

What does the attachment to a -mono or -poly ubiquitin chain do to the biological functions of a protein?

A
  • mono = change protein structure

- poly = marks protein for degradation in a proteasome

43
Q

What 3 enzymes does Ubiquitination require?

A

E1 - activating enzymes
E2 - conjugating
E3 - ligase

44
Q

What is a Proteasome and its function?

A

Large protein complexes inside all Eukaryotes and Archea

Main function to degrade unneeded/damaged proteins

45
Q

What is the main biological function of PolyUbiquitination and proteasomes?

A

Remove damage and misfolded proteins
Control lifespan of proteins
Control multicellular processes

46
Q

What is lipidation?

A

method to target proteins to membranes in organelles

47
Q

What are the 4 types of lipidation?

A

C-Terminal glycosyl (GPI)
N-Terminal Myristoylation
S-Myristoylation
S-Prenylation

48
Q

How is PTM relevant to medicine?

A

Defects in PTM and cell signalling - pathobiology

Enzymes controlling PTM - therapeutics

IMS (53 decks)

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