7 - Transmembrane Receptors Flashcards

1
Q

What are transmembrane receptors?

A

Transmembrane receptors are proteins that span the
thickness of the plasma membrane of the cell

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2
Q

Where is the transmembrane receptor in relation to the cell?

A

One end of the receptor is outside (extracellular domain)
and one end is inside (intracellular domain) the cell

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3
Q

What three sections of the receptor are there?

A
  1. extracellular - discriminator domain with ligand binding site
  2. transmembrane - transmembrane domain
  3. intracellular - effector domain
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4
Q

What three types of transmembrane receptors are there?

A
  1. protein kinase-coupled receptor
  2. G-protein-coupled receptor
  3. ion channel-coupled receptor
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5
Q

What effector domains do the three transmembrane receptors have?

A
  1. protein kinase-coupled receptor - 2 PK domains
  2. G-protein-coupled receptor - G protein
  3. ion channel-coupled receptor - none
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6
Q

What are drugs?

A

Drugs are receptor modulators and do not confer
new properties on cells and tissues

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7
Q

What can drugs do?

A

Drugs can enhance, diminish or block the generation,
transmission or receipt of a ligand-generated
signal by several mechanisms

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8
Q

How is the action of a drug classified?

A

The action of a drug is classified according to whether
it produces (agonist) or diminishes (antagonist)
the signal

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9
Q

What are the action pathways of drugs on receptors?

A
  1. input signal activates the ANTAGONIST, which interacts with the discriminator domain of the receptor, which is attached for the effect domain
  2. input signal activates the AGONIST, which interacts with the discriminator domain of the receptor, which is attached for the effect domain
    - there is a highly specific, non covalent interaction according to the lock-key principle (structural complementarity)
    - this may affect various signalling pathways
    -output signals are generated
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10
Q

What drugs antagonise. block, or inhibit endogenous proteins? (6)

A
  • Antagonists of Cell Surface Receptors
  • Antagonists of Nuclear Receptors
  • Enzyme Inhibitors
  • Ion Channel Blockers
  • Transport Inhibitors
  • Inhibitors of Signal Transduction Proteins
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11
Q

What drugs activate endogenous proteins?

A
  • Agonists of Cell Surface Receptors
  • Agonists of Nuclear Receptors
  • Enzyme Activators
  • Ion Channel Openers
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12
Q

How do drugs use sites on the receptor? (agonists and antagonists, allosteric agonists and antagonists, and other drugs)

A
  1. Agonists and antagonists compete with
    hormones/neurotransmitters for binding sites
  2. Allosteric agonists or antagonists enhance or
    block the signal by binding to allosteric sites
    that influence signal transmission
  3. Other drugs can block signal transduction
    within the membrane or at intracellular signal
    reception points
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13
Q

What mechanisms are used for the recognition of a drug or hormone by a receptor?

A

The recognition of a drug or hormone by a receptor
uses non-covalent mechanisms, such as hydrogen
bonds, electrostatic forces, hydrophobic and Van der
Waals forces

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14
Q

What chemical bonds are involved in drug actions (from strongest of weakest)?

A
  1. covalent
  2. ionic
  3. hydrogen
  4. hydrophobic
  5. van der Waals
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15
Q

Properties of most drug-receptor interactions

A
  • reversible
  • weak chemical bonds
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16
Q

Properties of irreversible drug-receptor interactions

A
  • not common
  • strong chemical bonds (covalent)
  • e.g. aspirin, anti-tumour drugs
  • usually undesirable
  • reversal of effects/toxicity
  • mutagenicity/carcinogenicity
17
Q

What four methods are used for studying cell signalling pathways>

A
  1. activation
  2. inhibition
  3. interaction
  4. cellular localisation
18
Q

What is involved in the ACTIVATION method for studying cell signalling pathways?

A
  • activator
  • constitutively active mutant transgene
19
Q

What is involved in the INHIBITION method for studying cell signalling pathways?

A
  • inhibitor
  • dominant-negative mutant
  • anti-sense mRNA
  • siRNA
  • gene knockout
20
Q

What is involved in the INTERACTION method for studying cell signalling pathways?

A
  • co-immunoprecipitation
  • yeast two-hybrid system
  • fluorescence resonance energy transfer (FRET)
21
Q

What is involved in the CELLULAR LOCALISATION method for studying cell signalling pathways?

A
  • cell fractionation
  • immunohistochemistry
  • GFP tagging