PHAR232 - Weeks 3 & 4 Flashcards

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1
Q

Do heart beta receptors decrease with age?

A

Yes

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2
Q

What are the 2 primary groups of receptors?

A
  • Ionotropic receptors
  • Metabotropic receptors
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3
Q

Are ionotropic receptors fast or slow?

A

Fast (milliseconds)

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4
Q

Name 3 examples of ligand-gated ion channels (ionotropic)

A
  • Nicotinic ACh receptor
  • GABA-A receptor
  • NMDA glutamate receptor
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5
Q

How many ACh ions are required to bind to open up a nicotinic ACh receptor?

A

2

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6
Q

What nutritional compound is bound to stabilize NMDA glutamate receptors and must leave before glutamate can bind?

A

MG2+

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7
Q

What are the 2 main positive ions for stimulatory influx?

A

Na+
Ca2+
(depolarisation)

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8
Q

What are the key INHIBITORY ions for ligand-gated ion channels?

A

K+ = (positive efflux) e.g. hyperpolarism
Cl- (negative influx)

Making the cell more negative

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9
Q

What is the GOAL of the ligand-gated ion channels?

A

To change membrane potential
- negative (hyperpolarise) or positive (depolarise)

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10
Q

What are some examples of G-protein coupled receptors?

A

0 Noradrenaline,
- Serotonin
- Muscarinic ACh
- Opioid
- GABA-B
- Histamine
- Prostaglandins

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11
Q

How many transmembrane domains do a GPCR have?

A

7

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12
Q

What is a newer GPRC type?

A

Protease-activated receptors (PARs)

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13
Q

List Protease-activated receptors (PARs) attributes

A
  • Tehtered ligand
  • Looks like GPCR
  • Interacts with GPCR
  • REGULATION VIA PHOSPHORYLATION
  • 1 use only
  • AGONIST IS PART OF THE RECEPTOR
  • Implicated as a ‘warning system’ for diseases
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14
Q
A
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15
Q

What is the newer GPCR that is activated by H+ ions?

A

proton-sensing

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16
Q

What’s the name of GPCR that are activated by specific lipids? e.g. lysophosphatidylcholine

A

lysolipid-sensitive GPCR

  • associated with cancers
  • Inflammation
  • Apoptosis
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17
Q

What is a GPCR that is highly associated with the parathyroid hormone?

A

calcium-sensing receptors

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18
Q

What are key physical aspects of the GPCR?

A
  • Heterotrimeric: 3 individual proteins in combination (alpha, beta, gamma)
  • ## 7 transmembraine domains
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19
Q

When speaking of a beta subtype - are we talking about 1. the ion channels or 2. the G-protein subtype?

A
  1. the g-protein subtype
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20
Q

What are key things that define an alpha subunit?

A
  • GTPases
  • THEY ARE AN ENZYME
  • alpha subunit a rest has GFP bound to it
  • at rest unit = alpha + beta + gamma
  • Activation = enzyme receptor changes shape for interaction
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21
Q

Alpha subunit shape change causes ________ to be DROPPED and _______ to be taken up?

A

GDP = DROPPED
GTP = INTAKE - active

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22
Q

What ACTIVATES the alpha subunit?

A

alpha subunit + GTP = active subunit

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23
Q
A
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24
Q

How could you think of cAMP as a pinball machine?

A

Goes around turning things on and off

25
Q

How many genes have been encoded so far for alpha subunits?

A

18 genes

26
Q

How many beta subunits have been encoded?

A

5

27
Q

How many gamma subunits have been encoded?

A

12

28
Q

Learn and DRAW OUT

A

MUST KNOW THIS PROCESS - DRAW IT OUT - LEARN

29
Q

WRITE OUT EXACTLY G PROTEIN SIGNALLING CASCADE

A
30
Q

Is beta-gamma often found connected as a subunit?

A

Yes

31
Q

What do GTPase-activating proteins (GAPS) do?

A

Bind to alpha subunits or small GTPases to increase rate of cleavage of phosphate from GTP
- E.G. CUT OFF THE GTP PHOSPHATE AS FAST AS POSSIBLE

= INACTIVATION OF SUBUNIT

32
Q

Is GTPase-Activating proteins (GAPS) a catalytic effect?

A

Yes

33
Q

What is RAS known as?

A

A low molecular weight GTPase (alpha)

34
Q

If you have an increase in GTPase-activating proteins, you shorten alpha subunit time (action)

A

§

35
Q

What is the job of GAPs aka GTPase-activating proteins?

A

Cut off the alpha phosphate as fast as possible

GTP = effect
GDP = stops working

= INACTIVATION OF SUBUNIT

36
Q

What does GEFs stand for?

A

Guanine Nucleotide Exchange Factors (GEFs)

37
Q

What do GEFs do?

A

ACTIVATE G-proteins or small GTPases by PROMOTING EXCHANGE OF GDP FOR GTP

38
Q

WHat is the particular GEF identified in the development of Alzheimer’s disease?

A

Presenilin

39
Q

How many distinct GEFs have been identified?

A

8

40
Q

What are the differences between GAPs and GEFs?

A

GAPS:
- Shortens alpha subunit activity = SHORTENS EFFECT OF RECEPTOR ACTIVATION
= DISCOURAGES GPCR SIGNALLING
= ‘OFF’

GEFs:
- ENCOURAGES activation of GPCR
- INCREASES receptor activation
= ‘ON’

41
Q

What does GDIs stand for?

A

Guanine Nucleotide Dissociation Inhibitors (GDIs)

42
Q

What do GDI’s do?

A

PREVENT ACTIVATION of G-proteins or small GTPases
- Stabilises proteins in GDP-bound form

43
Q

How many GDI’s have been identified?

A

10

44
Q

What is protein kinase A highly dependent on?

A

(cAMP) dependent protein kinase

45
Q

What does a kinase do?

A

Puts a phosphate (Pi) onto a protein from ATP

46
Q

What is protein kinase A (PKA) controlled by?

A

cAMP

47
Q

What is protein kinase G controlled by?

A

cGMP

48
Q

What is protein kinase C (PKC) controlled by?

A

DAG

49
Q

What was the original G-protein found?

A

Adenylate cyclase

50
Q

What is the key responsibility of adenylate cyclase (AdCy)?

A
  • Large enzyme responsible for conversion of ATP INTO cAMP!
51
Q

How many MEMBRANE-associated enzymes is Adenylate cyclase associated with?

A

9

52
Q

How many cytoplasmic enzymes is adenylate cyclase associated with?

A

1

53
Q

Is phospholipase C a catalytic enzyme?

A

Yes

54
Q

What 2 signalling molecules does phospholipase C make?

A
  • Inositol trisphosphate (IP3)
  • Diacylglycerol (DAG)
55
Q

What was Ip3 primarily do?

A

Activated IP3 receptors on endoplasmic reticulum to promote Ca2+ release

56
Q

What does diacylglycerol (DAG) primarily do?

A

Activates protein kinase C (PKC)

57
Q

What 2 molecules does phospholipase C use to produce IP3 and DAG?

A
  • Phosphatidylinositol
  • Bisphosphate
58
Q

REVIEW AND LEARN - WRITE IT OUT

A