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Bcem 431 > Lecture 12 > Flashcards

Lecture 12 Flashcards

1
Q

What is citrullination

A

An Argenine deamination PTM

Enzyme PAD makes the postive charge guanidinuim become neutral by turning =nh2+ into =O

Still polar

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2
Q

PAD and all of its isoforms are

A

Calcium dependent

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3
Q

What are NETs

A

Neutrophil extracellular traps

Form due to histone citrullination

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4
Q

What is lytic net formation

A

This is dependent on the ROS stress pathway (reactive oxygen species)

The ROS pathway activates pad 4

Pad 4 citrullinates histones

Chromatin decondenses and forms NETs

Neutrophil gets lysed to remove the NET and the trapped material

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5
Q

What things use lytic net formation

A

Fungus and bacteria since viruses are too small

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6
Q

What is (non lytic) net pathway

A

Activated by bacteria like e coli

The cell has TLR receptors (toll like receptors) thatt tecongize s.aureus or r coli

This receptor activate PAD 4 and nets are made

But the nets get secreted out of the cell

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7
Q

Histones can also act as

A

Antimocrobials

They can be secreted at part of the nets because they have anti microbial properties

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8
Q

What prevents citrullination on histones

A

Prior Methylation of the arg side chains

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9
Q

What happens to histones during various infections

A

Citrullination of them increases

This leads to the NETosis pathway

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10
Q

What is a disease caused by too much or a specific cltrullinated protein

A

MS- multiple sclerosis

What there’s too much myelin basic protien

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11
Q

Where does cirulination generally occur when it is a problem

A

Should only be inside the cell

If happen outside cell this is a sign that something is wrong and the proteins are recognized as non self by the immune system

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12
Q

What is special about rheumatoid arthritis patients and cirullinated proteins

A

They have antibodies against these proteins in their blood

These antibodies can be used as bio markers to diagnose people

Because the citrullinated protiens are recognized as non self by the immune system

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13
Q

What diseases are caused by citrullination

A

Sepsis

Kidney disease

Periodontis

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14
Q

What is special about some Covid patients and netosis

A

The netosis pathway in them leads to blood clotting

They need more respiratory support and have less survival

This is rare

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15
Q

What is special about some Covid patients and netosis

A

The netosis pathway in them leads to blood clotting

They need more respiratory support and have less survival

This is rate

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16
Q

What are the three ways to target proteins toward cell membranes

what do these all occur on

A

Myristoylation

Palmitoylation

Prenylation (also called hers geranyl geranylation )

All on cysteines

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17
Q

Where does myrisotylation occur

When is is done and is it reversible

A

Only at the n terminal glycine , intracellular

Done during protein folding (cotranslational)

Irreversible

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18
Q

What enzyme puts myristoyl groups onto the glycine

A

N-myristoyltransferase

Makes the protein a peripheral membrane protein

19
Q

Give an example of something that’s been myristoylated

A

Recoverin

20
Q

What is recoverin

A

A calcium myristoyl switch protein

Meaning when binding calcium, it exposes its hidden mysristotl group

Then gets anchored to the membrane

21
Q

How does recoverin function in dark

In light

A

It’s found in photoreceptors in the eye

It regulates the activity of rhodopsin kinase (phosohylrates rhodopsin to inactivate it)

In dark: recoverin binds ca, inhibits rhodopsin kinase. So now rhodopsin works and light response is longer

In light: ca low, recoverin not active. Rhodopsin kinase active, rhodopsin inactive and dark state is prolonged

22
Q

What is the holo and apo state of recoverin

A

Holo: ca bound, mystical exposed

Apo: no ca, myristoyl buried

23
Q

Recovering has how many EF hands

How many of them actually bind to ca

A

4
2

24
Q

What type of bond is myristoyl

A

Peptide

25
Q

What is palmitoylation

A

A palmitoyl group added posttranslationally

Added to cysteines

Reversible (enzyme can add and remove)

26
Q

For myristoyl group, what have they evolved to recognize and use to bind to membranes

A

Calcium

27
Q

For myristoyl group, what have they evolved to recognize and use to bind to membranes

A

Calcium

28
Q

What enzyme does palmitoylation

A

Palimtoyl transferase

29
Q

What enzyme removes the palmitoylation group

A

Palmitoyl thioesterase

30
Q

What an example of something that gets palmitoylated

A

The beta adrenergic receptor (a type of GPCR)

31
Q

Where are the n and c term domain of the beta adrenergic receptor

How many tranmembrane helices are there

A

N term is extracellular

C term is intracellular

7 transmembrane helices

32
Q

Where is the beta adrenergic receptor anchored

A

Near the C term by one single cysteine

33
Q

What happens if you mutate the cysteine residue that anchors the palmitoyl group in the beta adrenergic receptor

A

The beta adrenergic response stops functioning properly because it’s only held by that one residue

34
Q

What happens if you mutate the cysteine residue that anchors the palmitoyl group in the beta adrenergic receptor

A

The beta adrenergic response stops functioning properly because it’s only held by that one residue

35
Q

What is prenylation

What is the motif

A

Irreversible

Happens cotranslationally

CaaX Caa-X-C or C-C

A is an aliphatic amino acid

36
Q

What are the aliphatic amino acids

A

Alanine , valine , leucine, isoleucine, methionine, glycine

So nonpolar aa

37
Q

What are the three reaction that involve prnylation

A

A farnesyl transferase (prenyl transferase) has its substrate farnesyl pyrophosphate and adds it to cysteine

A Caax protease removes aax

CaaX methyltranferase adds a methyl group to the c term end

38
Q

What are the three reaction that involve prnylation

A

A farnesyl transferase (prenyl transferase) has its substrate farnesyl pyrophosphate and adds it to cysteine

A Caax protease removes aax

CaaX methyltranferase adds a methyl group to the c term end

39
Q

Slide 20

A

Okay

40
Q

Most lakmoat all lipidatwd proteins are

A

Anchored to the membrane

41
Q

Where do GPI anchors PTM happen

A

In the ER, not on the cell membrane

Attached to the c terminal end of the proteins

Bind to the membrane by the lipid group phospholipase c (PLC)

42
Q

Anything made in the et is destined to be

A

On the outside our the cell so they will all be extracellulr

43
Q

All gpi anchored proteins

A

pre proteins

Because they have a c terminal gpi anchor signal (which the gpi anchors to)

Only needs one cleavage so preprotien

It need to be cleaved twice it preproprotien

Bcem 431 (26 decks)

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