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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
GDP
Guanosine diphosphate + free phosphate (Pi)
26
What are the 3 heterodimer subunits?
1. Alpha 2. Beta 3. Gamma
27
Alpha s
Stimulation of adenylyl cyclase
28
Alpha i
Inhibition of adenylyl cyclase
29
Alpha q/11
Stimulation of PLC
30
What kind of energy activity does Alpha have?
GTPase activity GTP bound = active GDP bound = inactive
31
What do beta and gamma subunits act as?
Dimers
32
What are G proteins made up of? (3)
Alpha, beta and gamma subunits
33
G protein signalling general mechanisms (8)
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 7. Intrinsic GTPase of alpha converts GTP to GDP 8. Subunits re-associate (repeat)
34
What does alpha s effect? (3)
1. Adenylyl cyclase 2. Ca channels 3. K channels
35
What does alpha i effect? (3)
1. Adenylyl cyclase 2. Ca channels 3. K channels
36
What does alpha q effect? (1)
PLC-beta
37
ATP
Adenosine triphosphate
38
cAMP
Cyclic adenosine monophosphate
39
What is cAMP used for? (2)
1. Initiates the activation of protein kinase | 2. Regulates the passage of Ca through ion channels (2nd messenger)
40
G alpha s-AC coupled signalling steps (5)
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
PKA
Protein kinase A
42
CREB
cAMP response element binding protein
43
What do kinases do?
Add Pi
44
What do phosphotases do?
Remove Pi
45
What do cholera toxins do?
They block GTPase activity of alpha subunit and so cAMP stimulation constant
46
What are the agonistic effects of epinephrine? (chain reaction= AC, cAMP, PKA, proteins)
The activation if AC leads to the activation of cAMP which activates PKA which leads to increase activity for phosphorylation of proteins
47
What causes the phosphorylation of CREB?
PKA
48
What happens after the activation of PLC?
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
What is PIP2?
Minor phospholipid component of the cell membrane
50
G q -PLC coupled signalling steps (4)
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 4. PKC numerous substrates effects the nucleus
51
What do c-jun and c-fos make up?
They make a heterodimer which makes an important TF through activating AP1 - important in growth, cancer and oncogene
52
Desensitization of the beta-adrenergic receptor in g protein signalling steps (4)
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
BARK
Beta-adrenergic receptor kinase | --> A GPCR kinase
54
What does arrestin do?
It inhibits AC from binding and interacting with g alpha protein
55
Signalling complexes
Adds phosphate to substrate that recruit other proteins
56
Phosphorylation cascade
Adds phosphate to proteins that are also kinases
57
Growth factor receptors - signalling complexes steps (5)
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
Name 2 accessory proteins
1. SH2 | 2. SH3
59
What does SH2 do?
Recognizes phosphorylated tyrosines
60
What does SH3 do?
Recognizes proline rich sequences
61
SH2
Src homology domain (type 2)
62
SH3
Src homology domain (type 3)
63
PI3K
Phosphoinositide 3-kinase
64
PDK
PIP3-dependent kinase
65
PKB
Protein kinase B
66
GRB2
Growth factor receptor bound protein
67
SOS
Son of sevenless
68
MEK
Mitogen activated protein kinase
69
ERK
Extracellular signal-regulated kinase
70
MAPK
Microtubule associated protein kinase
71
MAPK pathway activated does what?
Mitogen activated protein kinase
72
PRL
Prolactin
73
What happens when a hormone binds to a cytokine receptor?
It dimerizes
74
JAK2
Janus kinase
75
STAT
Signal transducer and activators of transcription
76
What are 3 examples of STAT-binding DNA regulatory elements?
1. SIE 2. GAS 3. ISRA
77
What does JAK2 do?
It phosphorylates the STAT protein
78
What does guanylyly cyclase require?
GTP
79
What are the 2 major classes of GC?
1. Membrane bound | 2. Soluble
80
GC
Guanylyl cyclase
81
What are cytokines and what do they do?
They are small secreted proteins which mediate and regulate immunity, inflammation and hematopoiesis
82
Where are iNOS most likely found?
In inflammatory cells of the immune system
83
What is hepcidin and what does it do?
It is a polypeptide hormone that controls body iron levels
84
Where is hepcidin released from and when?
From the liver and when iron levels are high and there is inflammation
85
Why does hepcidin bind to ferroportin?
In order to control iron release from the gut, liver and WBCs
86
What happens when ferroportin binds?
It causes phosphorylation and ubiquinated and broken down (with the help from JAK2)

Bio 432 (19 decks)

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