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Bio 432 > Topic 3 - Mechanisms of Hormone Action -- Surface Receptors > Flashcards

Topic 3 - Mechanisms of Hormone Action -- Surface Receptors Flashcards

1
Q

What does the rate of association equal?

A

Rate of dissociation

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2
Q

[H]

A

Concentration of free hormone

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3
Q

[R]

A

Concentration of receptor

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4
Q

[HR]

A

Concentration of hormone-receptor complex or bound hormone

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5
Q

Kd

A

Equilibrium dissociation constant (defines affinity)

–> concentration of free H when 50% R are bound

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6
Q

What does the receptor tell you?

A

How sensitive the hormone was

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7
Q

What gets tagged with fluorescent?

A

The hormone

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8
Q

How do you find the receptors?

A

Use antibodies with fluorescent tags

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9
Q

What does Kd tell us?

A

Tells us how sensitive or how many receptors there are of the binding constant of the receptor to its hormone

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10
Q

What is the common form of most receptors?

A

Open and not bound (until more substrate is added)

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11
Q

What happens to the affinity when you have a low [H]?

A

You get a higher affinity

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12
Q

What happens to the [H] when you have a low affinity?

A

High [H]

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13
Q

Where would you find Ro on a graph?

A

X-intercept

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14
Q

What is the formula for slope on a scatchard plot

A
  • 1/Kd
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15
Q

What are the axis labels on a scatchard plot?

A 
y = [HR]/[H]
x = [HR]
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16
Q

ICYP

A

Iodocyanopindolo

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17
Q

What is a pindolol?

A

Nonselective beta blocker

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18
Q

What is ICYP, and what is its derivative used for?

A

It is a Beta1 receptor antagonist and its derivative is used in mapping the distribution of beta adrenoreceptors in the body

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19
Q

Where is ICYP produced?

A

In the adrenal medulla

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20
Q

What are the 5 main types of cell surface receptors?

A
  1. 7 transmembrane domain
    - GPCR
    - AC
    - PLC
  2. Growth factor receptor
    - tyrosine kinase domain attached
  3. Cytokine receptors
    - tyrosine kinase separate
  4. Guanylyl cyclase receptors
    - cyclase attached
  5. Novel cell surface receptors
    - ferroportin
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21
Q

AC

A

Adenylyl cyclase

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22
Q

PLC

A

Phospholipase C

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23
Q

G-protein receptor disease

A

Mutations in G protein receptors important pathology in endocrine disorders; often need homozygous mutation to have loss of function since excess receptors; also could have gain of function, if mutation causes constitutive activation; a single point mutation may also alter binding specificity or receptor desensitization

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24
Q

GTP

A

Guanosine triphosphate

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25
Q

GDP

A

Guanosine diphosphate + free phosphate (Pi)

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26
Q

What are the 3 heterodimer subunits?

A
  1. Alpha
  2. Beta
  3. Gamma
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27
Q

Alpha s

A

Stimulation of adenylyl cyclase

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28
Q

Alpha i

A

Inhibition of adenylyl cyclase

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29
Q

Alpha q/11

A

Stimulation of PLC

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30
Q

What kind of energy activity does Alpha have?

A

GTPase activity
GTP bound = active
GDP bound = inactive

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31
Q

What do beta and gamma subunits act as?

A

Dimers

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32
Q

What are G proteins made up of? (3)

A

Alpha, beta and gamma subunits

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33
Q

G protein signalling general mechanisms (8)

A
  1. Inactive complex
  2. Ligand binds creating a conformation change in receptor
  3. Receptor g-protein complex forms and GDP dissociates from alpha
  4. GTP binds
  5. G alpha -GTP dissociates from receptor and beta/gamma subunits
    6a. G alpha-GTP acts on the effectors (eg. PLC, AC)
    6b. beta/gamma can also act on effectors
  6. Intrinsic GTPase of alpha converts GTP to GDP
  7. Subunits re-associate (repeat)
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34
Q

What does alpha s effect? (3)

A
  1. Adenylyl cyclase
  2. Ca channels
  3. K channels
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35
Q

What does alpha i effect? (3)

A
  1. Adenylyl cyclase
  2. Ca channels
  3. K channels
36
Q

What does alpha q effect? (1)

A

PLC-beta

37
Q

ATP

A

Adenosine triphosphate

38
Q

cAMP

A

Cyclic adenosine monophosphate

39
Q

What is cAMP used for? (2)

A
  1. Initiates the activation of protein kinase

2. Regulates the passage of Ca through ion channels (2nd messenger)

40
Q

G alpha s-AC coupled signalling steps (5)

A
  1. Epinephrine binds beta-adrenergic receptor with G alpha s
  2. AC activated to produce cAMP from ATP
  3. cAMP binds to inhibitory subunit of PKA and releases enzyme
  4. PKA phosphorylates substrates
  5. CREB binds to consensus CRE
41
Q

PKA

A

Protein kinase A

42
Q

CREB

A

cAMP response element binding protein

43
Q

What do kinases do?

A

Add Pi

44
Q

What do phosphotases do?

A

Remove Pi

45
Q

What do cholera toxins do?

A

They block GTPase activity of alpha subunit and so cAMP stimulation constant

46
Q

What are the agonistic effects of epinephrine? (chain reaction= AC, cAMP, PKA, proteins)

A

The activation if AC leads to the activation of cAMP which activates PKA which leads to increase activity for phosphorylation of proteins

47
Q

What causes the phosphorylation of CREB?

A

PKA

48
Q

What happens after the activation of PLC?

A

Releases PIP2 and causes the release of Ca for the sER and increase of calmodulin and free Ca as a 2nd messenger in the cell

49
Q

What is PIP2?

A

Minor phospholipid component of the cell membrane

50
Q

G q -PLC coupled signalling steps (4)

A
  1. Ligand binds receptor with G alpha q
    2a. PIP2 is cleaved to IP3; releasing Ca from ER to cytoplasm; DAG is formed
    2b. DAG may come directly from phosphatidylchlorine cleavage
    3a. Ca activates PKs; promotes secretion = causes contraction
    3b. DAG activates PKC
  2. PKC numerous substrates effects the nucleus
51
Q

What do c-jun and c-fos make up?

A

They make a heterodimer which makes an important TF through activating AP1
- important in growth, cancer and oncogene

52
Q

Desensitization of the beta-adrenergic receptor in g protein signalling steps (4)

A
  1. Activation of receptor and AC
  2. Phosphorylation of receptor by BARK
  3. Inactivate AC; arrestin binds when pylated and clocks associated with G protein
  4. Phosphatase’s remove phosphate from receptor, allows g protein association and activation of AC
53
Q

BARK

A

Beta-adrenergic receptor kinase

–> A GPCR kinase

54
Q

What does arrestin do?

A

It inhibits AC from binding and interacting with g alpha protein

55
Q

Signalling complexes

A

Adds phosphate to substrate that recruit other proteins

56
Q

Phosphorylation cascade

A

Adds phosphate to proteins that are also kinases

57
Q

Growth factor receptors - signalling complexes steps (5)

A
  1. Dimers form upon ligand binding
  2. Autophosphorylation
  3. Recruitment of accessory proteins
  4. Sh3 proteins also have tyr phosphorylation
  5. Large complexes form with complicated signalling
58
Q

Name 2 accessory proteins

A
  1. SH2

2. SH3

59
Q

What does SH2 do?

A

Recognizes phosphorylated tyrosines

60
Q

What does SH3 do?

A

Recognizes proline rich sequences

61
Q

SH2

A

Src homology domain (type 2)

62
Q

SH3

A

Src homology domain (type 3)

63
Q

PI3K

A

Phosphoinositide 3-kinase

64
Q

PDK

A

PIP3-dependent kinase

65
Q

PKB

A

Protein kinase B

66
Q

GRB2

A

Growth factor receptor bound protein

67
Q

SOS

A

Son of sevenless

68
Q

MEK

A

Mitogen activated protein kinase

69
Q

ERK

A

Extracellular signal-regulated kinase

70
Q

MAPK

A

Microtubule associated protein kinase

71
Q

MAPK pathway activated does what?

A

Mitogen activated protein kinase

72
Q

PRL

A

Prolactin

73
Q

What happens when a hormone binds to a cytokine receptor?

A

It dimerizes

74
Q

JAK2

A

Janus kinase

75
Q

STAT

A

Signal transducer and activators of transcription

76
Q

What are 3 examples of STAT-binding DNA regulatory elements?

A
  1. SIE
  2. GAS
  3. ISRA
77
Q

What does JAK2 do?

A

It phosphorylates the STAT protein

78
Q

What does guanylyly cyclase require?

A

GTP

79
Q

What are the 2 major classes of GC?

A
  1. Membrane bound

2. Soluble

80
Q

GC

A

Guanylyl cyclase

81
Q

What are cytokines and what do they do?

A

They are small secreted proteins which mediate and regulate immunity, inflammation and hematopoiesis

82
Q

Where are iNOS most likely found?

A

In inflammatory cells of the immune system

83
Q

What is hepcidin and what does it do?

A

It is a polypeptide hormone that controls body iron levels

84
Q

Where is hepcidin released from and when?

A

From the liver and when iron levels are high and there is inflammation

85
Q

Why does hepcidin bind to ferroportin?

A

In order to control iron release from the gut, liver and WBCs

86
Q

What happens when ferroportin binds?

A

It causes phosphorylation and ubiquinated and broken down (with the help from JAK2)

Bio 432 (19 decks)

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