Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BMS 242 - Advanced Cell and Molecular > Signalling via intracellular receptors > Flashcards

Signalling via intracellular receptors Flashcards

1
Q

Which signals can pass through the membrane to interact with intracellular receptors?

A
  • Small molecules

- Hydrophobic molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What do cell-surface receptors do?

A

Bind hydrophillic signals (can’t cross the membrane) and TRANSDUCE the signals into an intracellular response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do molecules that bind intracellular receptors get into the cell?

A

Diffuse straight through the membrane
OR
Use carrier proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which 4 molecules bind to nuclear receptors?

A

1) Steroid hormones (testosterone, cortisol, estradiol)
2) Thyroid hormones (thyroxine)
3) Retinoids (retanoic acid - Vitamin A)
4) Vitamin D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What gases bing to intracellular receptors?

A 
Nitric oxide (NO)
Carbon monoxide (CO)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are 3 properties of NO?

A

1) Very small (only 2 atoms)
2) Gaseous
3) Free radical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a free radical and what can it do?

A

Unpaired electron in the outer shell
Very reactive
Can damage other proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are other nitric gases that are quite stable?

A 
Nitrogen Dioxide (NO2)
Nitrous Oxide (N2O)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How is NO made?

A
  • Substrate of L-arginine (an amino acid)
  • 2 successive oxidations
  • Producing L-citrulline, NO and water
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What enzyme produces NO from L-arginine?

A

NOS (Nitric oxide synthase)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is important about NOS?

A

Comes in various varieties, which are specific for function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is cNOS?

A

Constitutive NOS - when transcribed in the cell they are expressed all of the time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is the enzymatic activity of cNOS induced?

How long does the activity last for?

A

By Ca2+/Calmodulin

Activity is short-lived

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How much NO does cNOS produce?

A

Very small amounts (picomoles)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the 2 representatives of cNOS?

A

eNOS (endothelial)

nNOS (neural)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where is eNOS present?

A

At the CELL MEMBRANE

Expressed in:

  • Endothelium
  • Cardiac myocytes
  • Osteoblasts/osteoclasts
  • Platelets
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is nNOS present?

A

In the CYTOSOL

Expressed in:

  • CNA
  • NANC neurons
  • ENS
  • Retina
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is eNOs important in?

A

Vasculature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is iNOS?

A

Inducible NOS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How is iNOS different to cNOS?

A

Expression is inducible but the enzymatic activity is constitutive

Where as cNOS - the expression is constitutive but the enzymatic activity is regulated

iNOS also has a long-lasting effect and produces more NO

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

When is iNOS transcriptionally induced?

A

In response to pathological stimuli (LPS, IFN-g, IL-1)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Where is iNOS expressed?

A
  • Macrophages and Kupffer cells
  • Neutrophills
  • Fibroblasts
  • Vascular smooth muscle and endothelial cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What activates eNOS?

What does this cause?

A

Ach release from autonomic nerve terminals

Causes:
1) eNOs to act on L-arginine to make L-citrulline and NO

2) NO binds to guanylyl cyclase and converts GTP to cGMP
3) cGMP then binds to cGMP-dependant protein kinase (PKG) to acitvate it
4) PKG acts on myosin light chain phosphatase
4) MLCP removes phosphate from myosin light chain to cause RELAXATION OF THE MUSCLE

24
Q

What does NO released from eNOS inhibit?

A

Platelet aggregation and vascular smooth muscle proliferation

25
In the CNS, what is nNOS tethered close to in the cytosol? Why?
NMDA-type glutamate receptor on the postsynaptic membrane So that nNOS can respond to Ca2+ increases near the open channels
26
What is the process of nNOS activation and what does this cause?
1) Glutamate produced by presynapse 2) Glutamate bind NDMA glutamate receptor - releases Ca2+ 3) Ca2+ acitvates nNOs - synthesises NO 4) NO diffuses into the presynaptic terminal to activate glutamate production 5) Forms a positive feedback loop
27
What does the positive feedback loop of NO in the brain cause?
Long-term potentiation and memory | synaptic plasticity
28
What does NO do in the immune system?
- Kills bacteria an parasites | - Programmed cell death
29
What does iNOS do?
Triggers death at very high levels of NO | Cytostatic and cytotoxic agent
30
What causes rheumatoid arthritis, Crohn's disease and asthma?
- Inappropriately elevated levels of NO - causing inflammatory responses - Necrosis
31
What can nitroglycerine be used as? (2 things)
1) Dynamite (when mixed with fine clay) | 2) Angina treatment
32
How does nitroglycerine treat angina?
Administered as a spray | Rapidly breaks down in vivo to generate NO - relaxes blood vessels and lowers blood pressure
33
What does PDE5 do?
Recycles cGMP into GMP and then GTP, even when there is NO present (causes GTP-->cGMP) This prevents the build up of cGMP (which normally binds to cGMP-dependant protein kinase to produce smooth muscle contraction)
34
What is an inhibitor of PDE5? What is the consequence of this?
Viagra - cGMP builds up - Smooth muscles relax - More blood flow to the blood vessels
35
What is PDE5?
Phosphodiesterase 5
36
What makes the signalling molecules that bind to nuclear receptors hydrophobic?
Many carbon rings
37
What is the structure of a nuclear receptor?
1) Transcriptional activating domain 2) DNA-binding domain 3) Regulatory domain/ligand binding domain
38
What does the regulatory domain of a nuclear receptor bind?
1) Inhibitory proteins | 2) Bind the ligand
39
What does binding of the regulatory domain to an inhibitory protein do? (nuclear receptor)
Holds the receptor in an inactive state
40
What does binding of the regulatory domain to the ligand do? (nuclear receptor)
- Removes the inhibitory protein - Resulting in a conformational change - Binding coactivators
41
What drives the different effects between ligands in different tissues, in regards to a nuclear receptor? How?
Coactivators: - Nuclear receptors are the same in each tissue - Coactivators are tissue specific and modify the activit of the ligand
42
What does the DNA binding domain of the estrogen receptor consist of?
Zinc fingers
43
What are the biding sites divided into? What receptors bind here?
Inverted repeat (palindromic) - homodimers Direct repeat (tandem) - heterodimers
44
How do glucocorticoid and estrogen receprtors bind to DNA?
- Bind as symmetric homodimers to an inverted repeat DNA site - Bind palindromic sequence - 2 proteins face each other (mirror image of binding sequence) - Sequence separated by 3 nucleotides
45
How do receptors for Vitamin D, retanoic acid and thyroid hormone bind to DNA?
- As heterodimers to tandem repeats
46
What do the nuclear family members that form heterodimer bind to? What is important about this factor
RXR (retanoid X receptor) RXR is present and active all of the time, but can only activate transcription when there is a pairing of the second receptor
47
What is important in the response element of heterodimers?
The spacing between direct repeats
48
Where are homodimeric receptors found? Why are they found here?
In the cytoplasm in the absence of the ligand (in their inactive state) Anchored to the cytoplasm by inhibitor proteins, including Hsp90
49
What does hormone binding to homodimeric receptors cause?
Release of inhibitor protein - allowing them to enter the nucleus
50
Where are heterodimeric receptors located?
Exclusively in the nucleus at their binding site
51
How do heterodimeic receptors act in the absence and presence of the ligand? How do they do this?
Absense - Repressors by recruiting histone deacetylases Presence - activators by recruiting histone acetylases
52
How do the nuclear receptor family function? How is this different to insulin receptors?
Entirely by transcriptional regulation Insulin receptors also have a faster response - translocation
53
What is the response of nuclear receptors broken down into? Describe each stage
1) Early primary response - Receptors activate transcription of primary response genes 2) Delayed secondary response - Some primary response genes encode transcription factors and activates secondary response genes to create secondary response proteins
54
What are primary response genes?
Genes that are directly activated by the nuclear receptor
55
When does the early response occur?
1-6 hours after activation
56
When does the delayed response occur?
6-48 hours after activation

BMS 242 - Advanced Cell and Molecular (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions