Post-Translational Modifications Flashcards

Chapter 4

1
Q

Signal trasnducts requires ____ in some components of the cell in response to an incoming signal.

A

change

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2
Q

What kind of changes can PTMs provide for the protein?

A

rapid, specific, and tightly regulated changes

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3
Q

What is the functional consequence of PTM?

A

it changes the activity of the modified proteins (signaling currency)

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4
Q

What does PTM increase in the function of proteins?

A

it increases the functional diversity

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5
Q

What kind of modification is this an example of?

A

phosphorylation

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6
Q

What kind of modification is this an example of?

A

phosphorylation

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7
Q

What kind of modification is this an example of?

A

phosphorylation

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8
Q

What kind of modification is this an example of?

A

acetylation/deacetylation

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9
Q

What kind of modification is this an example of?

A

N-methylation

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10
Q

What kind of modification is this an example of?

A

N-methylation

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11
Q

What kind of modification is this an example of?

A

O-methylation

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12
Q

What kind of modification is this an example of?

A

Hydroxylation

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13
Q

What does glycosylation affect in proteins?

A

folding, trafficking, and function

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14
Q

Which type of glycosylation occurs on the hydroxyl group of ser/thr?

A

O-glycosylation

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15
Q

What type of glycosylation occurs on the amino group of asparagine?

A

N-glycosylation

polar

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16
Q

The addition of a single N-acetyl gluosamine (GlcNac) to ser/thr on cytosolic and nuclear proteins.

A

GlcNAcylation

transferase/hydrolase

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17
Q

Examples of simple fatty acids in lipid modification

A
  • myristate
  • palmitate
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18
Q

Examples of complex lipid groups in lipid modification

A
  • farnesyl group
  • geranylgeranyl group
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19
Q

S-palmitoylation to ____ is more dynamic and may play an active role in signaling.

A

cystine

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20
Q

What is ubiquitylation?

A

it is where Gly on ubiquitin interacts with Lys on a protein and binds to the substrate for modification

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21
Q

What is proteolysis?

A

The final process of protein degredation after ubiquitylation where the protein is degraded into peptide fragments

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22
Q

Describe the process of proteolysis of preproinsulin in the pancreas

A

1) preproinsulin - A chain, B chain, and C chain
2) proinsulin - Disulfide bonds form between A and B chains
3) insulin - Two disulfide bonds cut out the C chain

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23
Q

What catalyzes the rotation of a proline group about a peptide bond?

A

peptidyl prolyl cis-trans isomeras (PPIase)

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24
Q

What are some examples of the physical structure which PTMs can change?

A
  • shape
  • charge
  • hydrophobicity of the surface

global effect on proteins

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25
Q

What effect of protein modification (M) is depicted below?

A

change conformation, activity

26
Q

What effect of protein modification (M) is depicted below?

A

promote protein binding

27
Q

What effect of protein modification (M) is depicted below?

A

prevent protein binding

28
Q

What effect of protein modification (M) is depicted below?

A

change subcellular localization

29
Q

What effect of protein modification (M) is depicted below?

A

change proteolytic stability

30
Q

What is the writer and what is the eraser in this case?

A
  • writer - tyrosine kinase
  • eraser - tyrosine phosphatase

reader - SH2 domain

31
Q

What is the writer and what is the eraser in this case?

A
  • writer - histone acetyl transferase
  • eraser - histone deacetylase

reader - bromo domain

32
Q

What is the writer and what is the eraser in this case?

A
  • writer - ubiquitin ligase
  • eraser - deubiquitinase

reader - UIM domain

33
Q

What is the process where combination of modification site can result in a great number of potential molecular states of a single protein?

A

combinatorial complexity

34
Q

What is the formula for number of possible state per modification type?

A

2^n
(modification type)^(# of sites)

35
Q

One amino acid residue can be subjected to many different modifying enzymes, resulting in a ____.

A

competition

36
Q

Phosphorylation on Thr6 of histone H3 prevents the ability of LSD I (lysine demethylase) to bind, preserving methylation of Lys4. This would mean that this modification is ____.

A

antagonistic

ex. phosphorylation stimulated by androgen signaling

37
Q

What is p53 and what is it’s role in PTM?

A

p53 is a tumor supressor gene and has a wide variety of PTMs. Controls gene expression.

38
Q

Phosphorylation prevents p53 ____.

A

degradation

39
Q

NLS

A

nuclear localization signal

40
Q

NES

A

nuclear exocytosis signal

41
Q

What is unique about receptor tyrosine kinases (RTKs) in regards to their phosphorylation?

A

they can self-phosphorylate

42
Q

What can cause a foramtion of a large multicomponent signaling structure?

A

extensive phosphorylation

43
Q

List the steps that take place in this image.

A

1) ligand binding
2) receptor dimerization & catalytic domain activation
3) trans-phosphorylation and specific Y residues
4) effector recruitment to the cell surface

44
Q

What do all phosphospecific binding domain have that interacts with a phosphate group?

A

a positively charged pocket

45
Q

Nonspecific phosphatases coupled with ____ binding domains initiate the selection of substrates by kinases.

A

specific phosphoprotein

46
Q

What diverse mode of multiple phosphorylation is depicted?

A

priming

must be readily phosphorylated by another kinase

47
Q

What diverse mode of multiple phosphorylation is depicted?

A

processive phosphorylation

high processitivity; multiple phosphorylation events

48
Q

What diverse mode of multiple phosphorylation is depicted?

A

distributive phosphorylation

low processitivity; multiple rounds

49
Q

In multicellular organisms, which phosphorylations are the most common?
What are the other three residues which can be phosphorylated?

A
  • ser, thr, and tyr
  • his, asp, arg
50
Q

What is the ability of bacteria to swim towards or away from environmental cues?

A

chemotaxis

51
Q

List the bond that is formed between each residue.
* histidine
* aspartate
* ser, thr, tyr

A
  • phosphoramidate
  • acyl phosphate
  • phosphoester
52
Q

High energy bonds are ____ susceptible to hydrolysis.

A

more

53
Q

Ub

E1 activating enzyme works by…

A

attaching C-term of ub to a Cys on E1

54
Q

Ub

E2 ubiquitin conjugating enzyme works by…

A

activated ub gets attached to Cys on E2

55
Q

Ub

E3 ubiquitin ligase enzyme works by…

A

determining the specificity of substrate to be ubiquitylated

56
Q

Small hydrophobic patch on the surface of ubiquitin surrounding Ile41.

A

ubiquitin binding domain (UBDs)

57
Q

SUMO

A

small ubiquitin-like modifier

58
Q

Four isoforms of SUMO:
* trident
* K
* x
* D or E

A
  • hydrophobic
  • lysine
  • any amino acid
  • acidic residue
59
Q

Basic unit of chromatin

A

nucleosome

60
Q

What units make up the histone core?

A
  • H2A
  • H2B
  • H3
  • H4
    All of these x2

H1 is the clamp

61
Q

Histone modification is highly ____ and is subject to change over a ____ time scale.

A

dynamic; short

62
Q

____ is generally associated with transcriptionally active chromatin.

A

lysine acetylation