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BMS 242 - Core Phys/pharm > Receptor theory I > Flashcards

Receptor theory I Flashcards

1
Q

What 4 target proteins can drugs bind to?

A
  • Receptors
  • Enzymes
  • Transporters/carriers
  • Ion channels
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2
Q

What are receptors?

A
  • Translate extracellular message –> intracellular change

- Recognise and respond to endogenous chemicals

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3
Q

How are receptors identified and classified?

A

Structure, pharmacology and signalling

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4
Q

What are examples of endogenous compounds which receptors respond to?

A

Neurotranmitters and neuropeptides

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5
Q

What can happen if increase the concentration of a drug high enough, with a receptor that is doesn’t normally bind to?

What does this show?

A

Eventually will bind to the receptor - shows that no receptor is 100% specified

And that no drug acts with TOTAL specificity

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6
Q

How many transmembrane domains do G-protein receptors have?

A

7

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7
Q

How many transmembrane domains do ligand-gated receptors have?

A

4

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8
Q

How many transmembrane domains do kinase-linked receptors have?

A

1

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9
Q

How many transmembrane domains do nuclear receptors have?

A

0

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10
Q

What is another name for GPCR?

A

Metabotropic

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11
Q

What is another name for ligand-gated channels?

A

Ionotropic

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12
Q

Where are the N’ and C’ terminus of a GPCR?

A

N extracellular

C intracellular

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13
Q

Where are the N’ and C’ terminus of a ligand-gated channel?

A

Both extracellular

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14
Q

Where are the N’ and C’ terminus of a kinase-linked receptor?

A

N is intracellular

C is extracellular

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15
Q

What is the structure of a GPCR?

A
  • 3 intracellular loops
  • 7 transmembrane domains
  • N’ extracellular
  • C’ intracellular
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16
Q

How does the signalling of a GPCR occur? (heterotrimeric)

A

Through a cascade:

1) Ligand bind, activate GPCR
2) Creates Gprotein docking region
3) G protein bind
4) GDP released from Gprotein
5) GTP bind to Gprotein
6) alpha subunit dissociates from BY subunits
7) Activates other proteins/receptors

17
Q

What are the different alpha subunits of a Gprotein and what do they cause to happen?

A

1) Gs
- Stimulates adenylyl cyclase and guanylyl cyclase

2) Gi
- Inhibits AC ad GC

3) Gq
- Stimulates phospholipase C

18
Q

What are the 2 different types of Gprotein and how are they different?

A

1) Monomeric - made of one protein

2) Heterotrimeric - made of 3 DIFFERENT proteins (alpha, beta, gamma)

19
Q

How is the signalling of a heterotrimeric Gprotein stopped?

A

1) a subunit self hydrolyses GTP –> GDP
2) a subunit becomes inactivated
3) a subunit has high affinity for the BY subunit

20
Q

What do the BY subunit of the Gprotein activate?

A

Ligand-gated ion channels

21
Q

Which Gprotien subunits are bound to the plasma membrane?

A

alpha and gamma

22
Q

What does arrestin do?

A

Binds the the GPCR and stops the signalling

23
Q

What does phospholipase C do when is activated?

A

1) Hydrolyses PIP2 (membrane bound) into DAG (membrane bound) and IP3 (Cytosolic messenger)

2) IP3 diffuses into the ER
3) Releases Ca2+ stored in the ER into the cytosol

4) Ca2+ bind to receptors and cause further signalling events

5) Ca2+ causes PKC to move to the plasma membRane
6) PKC activated by DAG and bound CA2+

24
Q

What does activated protein kinases do?

A

Phosphorylates target proteins on serine and threonine residues

25
Q

What is PKA activated by?

A

ATP

26
Q

What is PKC activated by?

A

Calcium

27
Q

What are the 2 different types of kinase-linked receptors?

A

1) Receptors can BE a tyrosine kinase

2) Receptors can be ASSOCIATED with a tyrosine kinase

28
Q

What is an example of a monomeric Gprotein?

A

Ras GTPase

29
Q

What are Ras GTPases activated by?

A
  • Activating Ras-GEF

- Inhibiting Ras-GAP

30
Q

What is Ras-GEF and what do they do?

A
  • Guanine nucleotide exchange factors
  • Promote exchange of bound GDP –> GTP
  • Activate Ras
31
Q

What is Ras-GAP and what do they do?

A
  • GTPase - activating proteins
  • Increase speed of GTP synthesis
    Inactivate Ras
32
Q

What are Ras GTPases activated by

A

GDP–> GTP

33
Q

What are the downstream targets of receptor tyrosine kinases?

A

1) Map kinases, through a monomeric Gprotein (Ras GTPase)
2) PI3 kinases
3) Phospholipase C (gamma)

34
Q

What are the stages which occur when a receptor tyrosine kinase is activated?

A

1) Autophosphorylation or crossphorylation at the kinase domain
2) Then, can phosphorylate each other at tyrosine residues
3) Provides binding/docking/activation sites for other signalling molecules

35
Q

Examples of GPCR?

A
  • Muscarinic acetylcholine receptors
  • Rhodopsin
  • Opiate receptors
  • Dopamine receptors
  • Canaboid receptors
36
Q

Examples of kinase-linked receptors?

A
  • Cytokines
  • Chemokines
  • Growth factors

BMS 242 - Core Phys/pharm (13 decks)

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