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Fundamentals Of Living Cells > Receptor Mechanism > Flashcards

Receptor Mechanism Flashcards

1
Q

What does acetylcholine do in the salivary gland?

A

Secretion

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2
Q

What does acetylcholine do in the heart muscle?

A

Decreased rate and force of contraction

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3
Q

What does acetylcholine do in the skeletal muscle?

A

Contraction

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4
Q

What model do receptors work under?

A

Lock and key model

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5
Q

What’s the fastest receptor?

A

Ligand gated ion channel

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6
Q

What’s the slowest receptor?

A

Nuclear

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7
Q

Give examples of ligand gated ion channel agonists

A
  • nicotinic cholinoceptor 5HT3
  • acetylcholine 5HT
  • gamma amino butyrate acid (gaba) glycine
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8
Q

How many similar proteins does a ligand gated ion receptor have?

A

5

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9
Q

Where is the amino acid terminus in a ligand gated ion channel?

A

External

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10
Q

How many transmembrane domains do ligand gated ion channels have?

A

4

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11
Q

Which amino acids form domains and which form the chains between domains?

A

Hydrophobic amino acids form domains

Hydrophilic amino acids form the Chains

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12
Q

How many transmembrane domains do nicotinic acetylcholine have per protein?

A

4

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13
Q

What is the nicomic acetylcholine made up of?

A

2 alpha subunits
1 beta subunit
1 gamma subunit
1 delta subunit

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14
Q

How do the agonists activate the ligand gated ion channel?

A

Bind to the alpha subunits which causes a molecular kink

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15
Q

How do nicotinic and 5HT3 depolarise?

A

Na/Ca influx

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16
Q

How does GABAa and glycine hyperpolarise?

A

Chloride influx

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17
Q

What is the nicotinic acetylcholine receptor made up of in adult skeletal muscle?

A 
Alpha 1 
Epsilon
Alpha 1
Beta 1
Delta
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18
Q

What is the nicotinic acetylcholine receptor made up of in foetal skeletal muscle?

A 
Alpha 1
Gamma
Beta 1
Alpha 1
Delta
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19
Q

What’s the difference in function between nicotinic acetylcholine receptors in adult and foetal skeletal muscle

A

Adult- channel is open longer and brings in different molecules

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20
Q

What is the nicotinic acetylcholine receptor made up of in the CNS?

A

Alpha 2-4 and beta 2-4

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21
Q

Give symptoms of myasthesia gravis

A
  • muscle weakness
  • drooping eyelids
  • Fatigue
  • difficulty swallowing or talking
  • exertion is hard
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22
Q

What causes myasthesia gravis?

A

Muscle nicotinic acetylcholine receptors become degraded

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23
Q

What subunit does myasthesia gravis target?

A

The alpha 1 subunit

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24
Q

How much of the proteome is made up of G protein coupled receptors?

A

8%

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25
Q

Roughly what proportion of all pharmaceutical drugs target GPCRs?

A

30%

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26
Q

What subunits make up a GPCR?

A

Alpha, beta gamma (and GDP?)

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27
Q

What happens when the agonist binds to the GPCR?

A

There is a change in the affinity of the alpha subunit, so it binds to GTP which activates it

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28
Q

What happens when the alpha subunit is activated in GPCRs?

A

It dissociates from the beta gamma and interacts with other proteins

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29
Q

How many transmembrane domains do GPCRs have?

A

7

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30
Q

What does the alpha s do from GPCRs?

A

Stimulates

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31
Q

What does the alpha I do from GPCRs?

A

Inhibits adenyl cyclase

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32
Q

What does the alpha q do from GPCRs?

A

Interacts with the PLC beta

33
Q

What does the alpha 12/13 interact with from GPCRs?

A

RhoGEF

34
Q

What does adenylate cyclase do with alpha I?

A

Takes ATP-> activated pKA (v.basic)

35
Q

What does phosphodiesterase break down?

A

cAMP

36
Q

What does Gq/11 do?

A

Increased phospholipase C activity

37
Q

What does PIP2 stand for?

A

Phosphatidylinositol

38
Q

What does IP3 stand for?

A

Inositol triphosphate

39
Q

What does DAG stand for?

A

Diacylglycerol

40
Q

What is tyrosine receptor kinase involved in?

A

Insulin
Epidermal growth factor (EGF)
Platelet derived growth factor (PDGF)

41
Q

What is JAK/STAT involved in?

A

Growth hormone

Interferon

42
Q

What is serine threonine receptor kinase involved in?

A

TGF beta

43
Q

What are nuclear receptors involved in?

A

Glucocorticoid

Thyroid hormone

44
Q

What are enzyme-linked receptors involved in the regulation of?

A 
Cell growth
Division
Differentiation
Survival
Migration
45
Q

What is inappropriate enzyme linked receptor activity associated with?

A

Disease including cancer

46
Q

What does activation of enzyme-linked receptors lead to?

A

Actuation of receptor kinases

Activation of multiple signalling pathways

47
Q

What does dimerisation of tyrosine kinase linked receptors do?

A

Brings together two receptor molecules allowing autophosphorylation of specific tyrosine residues

48
Q

Can all tyrosine residues be phosphorylated?

A

No

49
Q

What does phosphorylation of tyrosine residues form?

A

Docking domains

50
Q

What do the proteins that bind to the docking domain of tyrosine kinase linked receptors recognise?

A

A specific AA sequence that includes a phosphorylated tyrosine residue

51
Q

What is a motif in tyrosine kinase linked receptors?

A

Specific AAs including a phosphorylated tyrosine residue

52
Q

What happens when grb-2 binds to the tyrosine through its SH2 domains?

A

Undergoes a conformational change which allows it to bind to another protein called GEF through the SH3 domain

53
Q

How is RAS GTP made from GEF?

A

RAS binds to GEF

GDP swapped for GTP

54
Q

What is ras?

A

Membrane associated protein that is bound to GDP

55
Q

What does PI3-kinase phosphorylate?

A

PIP2 to PIP3

56
Q

What does the insulin receptor consist of?

A

2 alpha chains

2 beta chains

57
Q

What are the subunits joined by in insulin receptors?

A

Disulfide bridges

58
Q

What happens to the insulin receptors when the insulin isn’t bound?

A

It doesnt allow the phosphorylation of receptors

59
Q

What happens in the insulin receptor when insulin is bound

A

There is a conformational change to the receptor which allows autophosphorylation to take place

60
Q

How does the insulin receptor substrate bind in the insulin receptor?

A

SH2 domain

61
Q

What do insulin receptors lead to in the liver and muscles?

A

Glycogen synthesis or protein synthesis

62
Q

What can insulin receptors lead to?

A

Stimulation of glucose transporters which increase glucose uptake

63
Q

What other proteins can insulin substrates recruit

A

Ras and phospholipase c

64
Q

How are phosphatase activated?

A

As a result of the receptor activation

65
Q

What do kinases add?

A

Phosphates

66
Q

What do phosphatase remove?

A

Phosphates

67
Q

What facilitates the inactivation of the molecules?

A

PTEN

68
Q

What enzyme is ras acted on by to speed up the inactivation?

A

GTPase activating protein (GAP) binds to the activated Ras and stimulates the GTPases which leads to the dissociation of GTP

69
Q

What can mutations in key regulatory mechanisms lead to?

A

Increase in receptor expression
Loss of phosphatase activity
Loss of GTPase activity
Loss of phosphatase activity

70
Q

What is jak-STAT signalling pathway activated by?

A

Growth hormone

71
Q

Give the JAK-STAT signalling pathway

A

Jaks cross-phosphorylate each other on tyrosine
Activated jaks phosphorylate receptors on tyrosine
STATs dock on phosphotyrosines and jaks phosphorylate them
STATs dissociate from receptors and dimerise via SH2 domain
Travels to the nucleus where it will stimulate and regulate the gene regulatory protiens

72
Q

What does the serine-threonine kinase require the presence of?

A

Two different types of receptor

73
Q

What is the serine-threonine kinase domain?

A

Type 2 receptor, by binding of TGF beta undergoes a conformational change

74
Q

What are intracellular receptors activated by?

A

Molecules that readily pass across the cell membrane and are largely insoluble in aqueous environments

75
Q

Give some intracellular receptor activators

A

Thyroid and steroid hormones and glucocorticoids

76
Q

What are the intracellular receptor activators delivered bound to?

A

Globulin including vit D

77
Q

In steroid receptors what does the binding of cortisol to a glucocorticoid receptor lead to?

A

Dissociation of the heat shock protein and the glucocorticoid receptor bound to the cortisol

78
Q

What does the glucocorticoid receptor- cortisol complex do in the nucleus?

A

Binds with the glucocorticoid response element which leads to an increase in gene transcription

79
Q

How do thyroid hormone receptors work?

A

T3 delivered to the cell bound to a binding globulin. Then it diffuses across the plasma membrane into the nucleus where it binds to the thyroid hormone receptor

Fundamentals Of Living Cells (41 decks)

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