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Pharmacology Test 1 > Membrane-Bound Receptors > Flashcards

Membrane-Bound Receptors Flashcards

1
Q

What is a receptor?

A

Protein or group of proteins, usually embedded in cell membrane that allows cell to collect information about its surroundings

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2
Q

What is a ligand?

A

A chemical messenger (small molecule or peptide) that binds and stabilizes conformation of receptor.

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3
Q

What is a conformation change?

A

Change in shape of receptor that induces some downstream signal transduction

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4
Q

What are receptors roles in normal physiological processes?

A

Point of control. Receptor function is regulated by molecules supplied by body.

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5
Q

Can a drug make a cell perform a new function it does not normally do?

A

No

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6
Q

What is potency of a drug?

A

Affinity of the drug for a receptor. I.E. How tightly the receptor binds

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7
Q

What is the efficacy of a drug?

A

The intrinsic activity of the rug; magnitude of drug’s effect.

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8
Q

What is an agonist?

A

Drug combines with receptor to stimulate target organ. Stabilizes the receptor in active conformation.

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9
Q

What is an antagonist?

A

Drug combines with receptor, but interferes with naturally occurring agonist or agonist drug.

  • Simply interferes with agonist binding. The normal conformation fluctuation continue as if nothing was there.
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10
Q

A ligand that binds to a receptor and activates it is called an _____

A

agonist

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11
Q

A ligand that binds to a receptor and prevents it from activating is called an ____

A

antagonist

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12
Q

What does it mean when a drug binds to an orthosteric site?

A

Drug acts on main binding site of the receptor. “Traditional” way

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13
Q

What does it mean when a drug binds to an allosteric site?

A

Drug acts on an accessory binding site of a receptor. Stimulates the receptor in a “non traditional” way

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14
Q

What is a pore blocker?

A

Physically obstructs the channel (i.e. ion blocker). Local anesthetics use this as 1 mechanism of action

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15
Q

What is the benefit for allosteric drugs?

A

Tends to be less side effects. It is hard not to overdo it with an orthosteric binding site.

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16
Q

Is a receptor in a static state inside the body?

A

No, the receptor fluctuates between different natural conformations. Some are associated with pharmacological activity, some are not. They can fluctuate between:

1) Active
2) Partially active
3) Inactive

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17
Q

What is a partial agonist?

A

Weakly stabilizes the active state (~50% of time) or stabilize partially active state.

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18
Q

What is an inverse agonist?

A

Holds receptor in inactive state reversing baseline receptor activity. Stabilizes inactive form. AKA Supraantagonist.

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19
Q

What is noncompetitive antagonism?

A

Drug forms covalent bond. No matter what dose you give of agonist, you won’t be able to overcome the antagonist, thereby reducing efficacy.

The higher the dose of antagnoism, the greater decrease in efficacy when agonist given.

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20
Q

What is competitive antagonism?

A

Antagonist that forms weaker bonds (i.e. ionic, van der waals, H bonds). These “pop off and on” the receptor. In this case, when competitive antagonist given, enough dose of agonist drug will allow you to achieve same efficacy.

Most molecules wins in competitive antagonism.

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21
Q

What is the location of ligand-gated ion channels?

A

Membrane

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22
Q

How fast does a ligand gated channel act?

A

Milliseconds

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23
Q

Examples of ligand gated ion channel?

A

Nicotinic ACh receptor GABA(a) receptor

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24
Q

What is the effector of ligand-gated ion channels?

A

Ion channel

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25
Q

What is coupling of ligand gated ion channel?

A

Direct

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26
Q

What is the structure of ligand gated ion channels?

A

Oligomeric assembly of subunits surrounding a central pore

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27
Q

What is the location of G-protein coupled receptors on the cell?

A

Membrane

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28
Q

What are the effectors for G-protein coupled receptors?

A

Channel or enzyme. Usually both at same time

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29
Q

What is coupling for g-protein coupled receptors?

A

G protein or arrestin

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30
Q

What are examples of G protein-coupled receptors?

A

Muscarinic ACh receptor

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31
Q

What is the structure of G protein-coupled receptors?

A

Monomeric or oligomeric assembly of subunits comprising seven transmembrane helices with intracellular G protein-coupling domain

32
Q

What is the location of receptor kinases?

A

Membrane

33
Q

What is the effector for receptor kinases?

A

Protein kinases

34
Q

What is the coupling for receptor kinases?

A

Direct

35
Q

What are examples of receptor kinases?

A

Insulin, growth factors, cytokine receptors

36
Q

What is the time scale for kinase linked receptors?

A

Hours

37
Q

What is time scale for G protein coupled receptors?

A

Seconds

38
Q

What is another name for ligand-gated ion channels?

A

Ionotropic receptors.

39
Q

What is another name for G protein-coupled receptors?

A

Metabotropic

40
Q

What is the structure of a receptor kinase?

A

Single transmembrane helix linking extracellular receptor domain to intracellular kinase domain`

41
Q

Where is location of nuclear receptors?

A

Intracellular

42
Q

What is effector of nuclear receptors?

A

Gene transcription

43
Q

What is coupling of nuclear receptors?

A

Via DNA

44
Q

What are examples of nuclear receptors?

A

Steroids, birth control

45
Q

What is time scale for nuclear receptors?

A

Hours

46
Q

What is structure of nuclear receptors?

A

Monomeric structure with receptor and DNA-binding domains

47
Q

What do ion channels do?

A

Allow ions to move

48
Q

What is the resting membrane potential of membrane?

A

Around -70 mV

49
Q

What does excitatory mean?

A

Inside of cells’ charge approaches 0mV

  • generally by letting positive ions into cell
50
Q

What does inhibitory mean?

A

Inside of cell’s charge becomes more negative

-Generally by letting negative (mainly chloride) into the cell. (as well as K out)

51
Q

What are some properties of ligand gated ion channels?

A
  • Fast transmission
  • Composed of several subunits around central ion pore.
  • Agonist binding opens pore
52
Q

What are major families of ligand gated ion channels?

A
  • Cys-loop receptors
  • Ionotropic glutamate receptors
53
Q

Examples of cys-loop receptors?

A

Nicotinic Ach, 5HT-3 (serotonin) receptors, GABAa receptors, Glycine receptors, histamine, alcohol (Pentamer structure)

54
Q

Examples of ionotropic glutamate receptors

A

AMPA

NMDA Kainate (tetramer structure)

55
Q

What are cys-loop structures named for?

A

Loop formed by disulfide bond between two cysteines near N-terminus

56
Q

What are cys-loop receptors made of?

A

5 subunits around central pore alpha, beta, gamma, delta, epsilon

57
Q

What are examples of excitatory cys-loop receptors?

A

Nicotinic ACh, serotonin receptors

58
Q

What are examples of inhibitory cys-lop receptors

A

Glycine, GABA

59
Q

What generally obstructs ion pore in ligand gated channel cys-loop receptors?

A

Second transmembrane of alpha subunit. Agonist binding changes conformation. moving obstruction and allowing ions to flow through.

60
Q

What are examples of drugs that affect cys-loop receptors?

A

Nicotinic ACh: Nicotine, Chantix

GABAa: Ambien, barbituates, benzos, alcohol

61
Q

What is the reason for coadministration of barbituates, benzos, alcohol being so dangerous?

A

They all bind to separate sites on GABAa receptors. They do not compete for binding sites, so each additional drug causes inhibition of receptor

62
Q

What are drugs that effect glutamate receptors?

A

NMDA: Ketamine

AMPA: aniracetam (cognition enhancer)

63
Q

What is structure of nicotinic ACh receptors at NMJ?

A

two alpha (α), one beta (β), gamma (γ), delta (δ) subunit

64
Q

What is structure of channel for neuronal nAChRs

A

Only alpha and beta

65
Q

What do excitatory nicotinic ACh receptors allow to pass?

A

Na, K and some Ca ions

66
Q

What do nAChRs do in brain?

A

Nicotinic ACh receptors upregulate in response to chronic nicotine (like smoking)

67
Q

What are NaChR activation states?

A

Closed, desensitized, open

68
Q

What are examples of ionotropic glutamate receptors?

A

AMPS, NMDA, Kainate

69
Q

What do excitatory glutamate receptors allow to pass?

A

Na, K

NMDA can also pass Ca ions

70
Q

What are glutamate receptors comprised of?

A
  • Composed of four subunits
    • each subunit has four transmembrane domains
    • second TM domain forms ion pore
  • Each subunit has binding site- not all binding sites are for glutamate
71
Q

What is required to bind to NMDA receptor for the channel to open?

A
  • 2 Glutamate
  • 2 glycine
  • all four must be boudn for channel to open
72
Q

What is long term potentiation?

A

The more often neuron fires, the stronger the synapse gets

-Implicated in learning and memory

73
Q

What is blocking NMDA receptors at RMP?

A

Mg ion

74
Q

What causes Mg ion blocking NMDA receptors to move?

A

Depolarization of membrane by AMPA receptors

75
Q

What passes through NMDAr once open?

A

Ca

76
Q

What happens to Calcium that passes through NMDAr?

A

Activates CaMKII (Ca-calmodulin kinase II) which leads to more AMPAr’s being inserted into synapse.

More AMPArs= stronger synapse

77
Q

What is another name for NMDAr’s?

A

“Coincidence detectors” since it requires pre and post synaptic events in order to depolarie.

Pharmacology Test 1 (3 decks)

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