Post-Translational Modifications

Question 1

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

Answer 1

change

Question 2

What kind of changes can PTMs provide for the protein?

Answer 2

rapid, specific, and tightly regulated changes

Question 3

What is the functional consequence of PTM?

Answer 3

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

Question 4

What does PTM increase in the function of proteins?

Answer 4

it increases the functional diversity

Question 5

What kind of modification is this an example of?

Answer 5

phosphorylation

Question 6

What kind of modification is this an example of?

Answer 6

phosphorylation

Question 7

What kind of modification is this an example of?

Answer 7

phosphorylation

Question 8

What kind of modification is this an example of?

Answer 8

acetylation/deacetylation

Question 9

What kind of modification is this an example of?

Answer 9

N-methylation

Question 10

What kind of modification is this an example of?

Answer 10

N-methylation

Question 11

What kind of modification is this an example of?

Answer 11

O-methylation

Question 12

What kind of modification is this an example of?

Answer 12

Hydroxylation

Question 13

What does glycosylation affect in proteins?

Answer 13

folding, trafficking, and function

Question 14

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

Answer 14

O-glycosylation

Question 15

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

Answer 15

N-glycosylation

polar

Question 16

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

Answer 16

GlcNAcylation

transferase/hydrolase

Question 17

Examples of simple fatty acids in lipid modification

Answer 17

• myristate
• palmitate

Question 18

Examples of complex lipid groups in lipid modification

Answer 18

• farnesyl group
• geranylgeranyl group

Question 19

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

Answer 19

cystine

Question 20

What is ubiquitylation?

Answer 20

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

Question 21

What is proteolysis?

Answer 21

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

Question 22

Describe the process of proteolysis of preproinsulin in the pancreas

Answer 22

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

Question 23

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

Answer 23

peptidyl prolyl cis-trans isomeras (PPIase)

Question 24

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

Answer 24

• shape
• charge
• hydrophobicity of the surface

global effect on proteins

Question 25

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

Answer 25

change **conformation**, activity

Question 26

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

Answer 26

**promote** protein binding

Question 27

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

Answer 27

**prevent** protein binding

Question 28

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

Answer 28

change subcellular **localization**

Question 29

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

Answer 29

change proteolytic **stability**

Question 30

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

Answer 30

* writer - tyrosine kinase * eraser - tyrosine phosphatase | reader - SH2 domain

Question 31

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

Answer 31

* writer - histone acetyl transferase * eraser - histone deacetylase | reader - bromo domain

Question 32

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

Answer 32

* writer - ubiquitin ligase * eraser - deubiquitinase | reader - UIM domain

Question 33

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

Answer 33

combinatorial complexity

Question 34

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

Answer 34

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

Question 35

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

Answer 35

competition

Question 36

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 ____.

Answer 36

antagonistic | ex. phosphorylation stimulated by androgen signaling

Question 37

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

Answer 37

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

Question 38

Phosphorylation prevents p53 ____.

Answer 38

degradation

Question 39

NLS

Answer 39

nuclear localization signal

Question 40

NES

Answer 40

nuclear exocytosis signal

Question 41

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

Answer 41

they can self-phosphorylate

Question 42

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

Answer 42

extensive phosphorylation

Question 43

List the steps that take place in this image.

Answer 43

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

Question 44

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

Answer 44

a positively charged pocket

Question 45

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

Answer 45

specific phosphoprotein

Question 46

What diverse mode of multiple phosphorylation is depicted?

Answer 46

priming | must be readily phosphorylated by another kinase

Question 47

What diverse mode of multiple phosphorylation is depicted?

Answer 47

processive phosphorylation | high processitivity; multiple phosphorylation events

Question 48

What diverse mode of multiple phosphorylation is depicted?

Answer 48

distributive phosphorylation | low processitivity; multiple rounds

Question 49

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

Answer 49

* ser, thr, and tyr * his, asp, arg

Question 50

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

Answer 50

chemotaxis

Question 51

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

Answer 51

* phosphoramidate * acyl phosphate * phosphoester

Question 52

High energy bonds are ____ susceptible to hydrolysis.

Answer 52

more

Question 53

# Ub E1 activating enzyme works by...

Answer 53

attaching C-term of ub to a Cys on E1

Question 54

# Ub E2 ubiquitin conjugating enzyme works by...

Answer 54

activated ub gets attached to Cys on E2

Question 55

# Ub E3 ubiquitin ligase enzyme works by...

Answer 55

determining the specificity of substrate to be ubiquitylated

Question 56

Small hydrophobic patch on the surface of ubiquitin surrounding Ile41.

Answer 56

ubiquitin binding domain (UBDs)

Question 57

SUMO

Answer 57

small ubiquitin-like modifier

Question 58

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

Answer 58

* hydrophobic * lysine * any amino acid * acidic residue

Question 59

Basic unit of chromatin

Answer 59

nucleosome

Question 60

What units make up the histone core?

Answer 60

* H2A * H2B * H3 * H4 *All of these x2* H1 is the clamp

Question 61

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

Answer 61

dynamic; short

Question 62

____ is generally associated with transcriptionally active chromatin.

Answer 62

lysine acetylation