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Cell Bio And Disease > Post Translational Modifications > Flashcards

Post Translational Modifications Flashcards

1
Q

What do ptms get added to

A

Proteins post translation

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2
Q

How is it possible there’s more proteins than mrna

A

Because of ptms

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3
Q

What is the definition of ptms

A

Covalent addition or cleavage to a terminal or aa chain

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4
Q

Ptms are said to add diversity to 21 aa, how

A

Additional of functional groups like phosphate, acetyl,methyl, carb,lipid

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5
Q

What are pluripotent stem cells and where they found

A

Stem cells (embryonic) which are taken from blastocyst and can differentiate into any type of cell

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6
Q

What 3 germ layers can pluripotent sc differentiate into

A

Ectoderm, mesoderm, endoderm

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7
Q

How are PTMs involved in pluripotency

A

Control direction and differentiation of the pluripotent sc

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8
Q

How can ptms be used to make induced psc

A

They can revert differentiated cells back via ptm of specific transcription factors

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9
Q

How are multipotent sc diff (adult sc Eg bone marrow)

A

Are limited into what type of cell they differentiate into

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10
Q

Are ptms reversible

A

Some are, some are irreversible

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11
Q

Give example of cleavage of proteins needed for activation (in er)

A

When some membrane proteins/secretory proteins produced on ribosomes in er, they enter the er and the signal peptide for localisation is cleaved by signal peptidases

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12
Q

Where other than er can more cleavage be done to activate proteins like insulin

A

Golgi transport after er

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13
Q

What is needed for insulin cleavage in Golgi for activation

A

Carboxypeptidase e (remove basic residues from c terminal) and proteases (also liberate c terminal)

This is after n terminal signal peptidase

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14
Q

When are functional groups added like ubiquitination,phos in PtMs

A

Only in response to signal like oxidative stress

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15
Q

What machine can detect ptms on proteins

A

Mass spectrometer

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16
Q

Is phosphorylation reversible ptm

A

Yes

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17
Q

How does phos both activate or deactivate

A

Can either mask bs/as on proteins or allow interaction with other proteins/molecules

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18
Q

How does protein kinase work

A

Atp hydrolysis to add a P to a hydroxyl end on a protein

The H from hydroxyl is removed (O) bond

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19
Q

What residues are usually phosphorylsted via their hydroxyl end

A

Serine, threonine, tyrosine

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20
Q

Which conserved domain do most kinases have which is homologous

A

Eukaryotic protein kinase domain

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21
Q

Is kinase activity favoured

A

Yes. Free energy when phosphate bond broken in atp

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22
Q

How do phosphatases work

A

Hydrolysis of the phosphoric acid monoester

Reforms atp

Add H back to hydroxyl group

23
Q

Explain how glycogenolysis is a phosphorylation cascade

A

Epinephrine binding

Camp activated

Activated pka

Phosphorylates phosphorylase kinase

Phosphorylase kinase then phosphorylates glycogen phosphorylase = active to breakdown glycogen

24
Q

How are monosaccharides added to hydroxyl groups on proteins in glycolysation

A

After production of monosaccharides they get added via glycosyltransferases, forming covalent glycosidic bond

25
Q

Where does most glycosylation occur (N glycans in particular)

A

Inside the er after ribosome protein production

26
Q

What is a core glycan made from

A

2 x gluNac (n acetyl glucosamine)

3x mannose

27
Q

How many different monosaccharides can be added in glycosylation to how many aa

A

13

8 diff aa

28
Q

What are some functions of glycosylation

A

Protein folding
Immunology (MHC are glycoproteins, ab)
Cell adhesion and interaction
Embryonic development

29
Q

What helps oligosaccharides transfer to the protein hydroxyls in glycosylation

A

Dolichol

30
Q

First type of glycosylation is N linked. Describe where and examples

A

Glycosylation on asparagine OH

In ER

Eg insulin receptors, extracellular matrix

31
Q

What is O linked glycosylation

A

Glycosylation at OH of serine or threonine

32
Q

Where does O linked glycosylation occur

A

Er, Golgi, cytosol and nucleus

33
Q

Give examples of O linked

A

ECM, pathogenic toxins, collagen

34
Q

Other than n and onlinked what are the other 3

A

Glypiation

C linked

Phosphoglycosylation

35
Q

What is glypiation and give example

A

Core glycan (2 gluNac,3man) added to both phospholipid and protein

= in anchor cell surface proteins

36
Q

What is c linked glycosylation

A

Mannose glycosylation

Binds to an Indole ring on tryptophan

37
Q

Where is c linked glycosylation

A

Only in mammals

ECM

38
Q

What is phosphoglycosylation

A

Glycan binds serine through a phosphodiester bond

39
Q

Which ptm can be both co translational or post translation

A

Acetylation/deacetylation

40
Q

What is acetylation related to via function

A

Gene expression

41
Q

What are the 2 types of acetylation

A

N terminal (80-90%)

Lysine acetylation

42
Q

What is n terminal acetylation

A

Acetyl added to amino group of first aa

Happens co translationally

Most proteins have n terminal acetylation (80%)

43
Q

Which enzymes involved in n terminal acetylation which happens cotranslation

A

NATs

N terminal acetyl transferases

44
Q

Give example of lysine acetylation

A

To control gene exp via chromatin remodelling. Lysine gets acetylated (HATs)

Also p53 residues get acetylated

45
Q

Which enzymes are targeted for cancer therapeutics

A

HDACs

HDAC inhibitors are used to treat T cell lymphoma

46
Q

What is the purpose of n terminal acetylation

A

Localisation and stability of proteins

47
Q

Which residues get methylated (monomethyl,di or tri)

A

Lysine or arginine

48
Q

Where is methyl donated to methylases from

A

S adenosylmethionine

49
Q

Which type of methylation is reversible

A

Carbonyl methylation

50
Q

Which methylation is irreversible

A

Nitrogen methylation

51
Q

What is arginine methylation for

A

Rna processing and txn regulation
Dna damage repair
Protein translocation

52
Q

What is lysine methylation for

A

Histone remodelling to control levels of expression
Epigentic regulation of txn

(Via HKMT)

53
Q

What is p53 rich in which allows acetylation and methylation

A

Lysine and arginine

54
Q

Why is acetylation advantageous of p53 via cbp /p300

A

It allows better access for p53 to dna makes nucleosomes less wrapped

Cell Bio And Disease (18 decks)

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