Receptors and signalling molecules as drug targets Flashcards

1
Q

What are the 4 super-families of receptors?

A

Ligand-gated ion channels
G protein-coupled receptors
Kinase-linked receptors
Nuclear receptors

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2
Q

How fast does a response occur in a ligand-gated ion channel?

A

Within milliseconds

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3
Q

Which ions are nicotinic acetylcholine receptors permeable to?

A

Na+, K+ and Ca2+

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4
Q

What 2 full agonists act on nicotinic acetylcholine receptors?

A

Acetylcholine
Nicotine

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5
Q

What is the use of varenicline?

A

It blocks nicotine binding to the α4ß2 nACh receptor and exerts partial agonist activity at the receptor. This makes it a useful drug to reduce nicotine cravings

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6
Q

How fast does a response occur in a G protein-coupled receptor?

A

Within seconds

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7
Q

What category of receptors are an example of G protein-coupled receptors?

A

Adrenoceptors

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8
Q

What are the different types of adrenoceptor?

A

α1- adrenoceptors
α2 - adrenoceptors
ß1 - adrenoceptors
ß2 - adrenoceptors
ß3 - adrenoceptors

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9
Q

What physiological effects are caused by activation of α1 adrenoceptors?

A

Vasoconstriction of blood vessels

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10
Q

What physiological effects are caused by activation of α2 adrenoceptors?

A

Presynaptic inhibition of noradrenaline in the CNS and relaxation of the GI tract

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11
Q

What physiological effects are caused by activation of ß1 adrenoceptors?

A

Increased heart rate and cardiac muscle contraction

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12
Q

What physiological effects are caused by activation of ß2 adrenoceptors?

A

Dilation of the bronchi
increased heart rate and cardiac muscle contraction

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13
Q

What physiological effects are caused by activation of ß3 adrenoceptors?

A

Thermogenesis in skeletal muscle and lipolysis

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14
Q

What occurs when adrenaline binds to the ß2 adrenoceptor?

A

The receptor causes the replacement of GDP with GTP, which is connected to Gαs and Gßγ
The Gαs and GTP then activates adenylyl cyclase
This converts AMP into cAMP (cyclic)
This activates Protein Kinase A
This causes inhibition of MLCK activity which in turn causes bronchodilation

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15
Q

What occurs when adrenaline binds to α2 adrenoceptors?

A

The receptor causes the replacement of GDP with GTP, which is connected to Gαi and Gßγ
The Gαi and GTP inhibit the action of adenylyl cyclase
This prevents formation of cAMP
The Gßγ stimulated the opening of K+ ion channels
These both cause relaxation of the GI tract

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16
Q

What occurs when adrenaline binds to α1-adrenoceptors?

A

The receptor causes the replacement of GDP with GTP, which is connected to Gαq and Gßγ
The Gαq and GTP activate the enzyme Phospholipase C
This allows for the conversion of PIP2 to DAG and IP3
This increases levels of Ca2+
This causes vasoconstriction

17
Q

How is salbutamol used in the treatment of acute symptoms of asthma?

A

It binds to and activates ß2-adrenoceptors, leading to bronchodilation

18
Q

What occurs due to overexposure to salbutamol?

A

Receptors are down-regulated and are internalised to decrease activation of receptors
Phosphodiesterases also terminate the action of cAMP

19
Q

How is theophylline used in the treatment of COPD?

A

It is a phosphodiesterase inhibitor, so allows for continued cAMP action, meaning long lasting bronchodilation

20
Q

How long after activation, does a response occur in a kinase-linked receptor?

A

In hours

21
Q

What occurs in response to activation of an insulin kinase-linked receptor?

A

Insulin binds to the receptor and causes a conformational change
This allows binding of relay proteins to the protein kinases
This allows many different cellular responses

22
Q

What is an example of a nuclear receptor?

A

Steroid receptors

23
Q

How do steroid receptors work?

A

Steroid hormones can pass through the cell membrane
Here, they bind to the steroid receptors
This complex then moves through the nuclear pores and into the nucleus
Here, it binds to a ligand-binding domain sites on chromatin, activating transcription

24
Q

What is the use of Sodium valproate?

A

It is a broad spectrum anti-epileptic drug

25
Q

How does sodium valproate work?

A

It is a weak inhibitor of GABA transaminase, increasing GABA levels.
GABA is a inhibitory neurotransmitter
It is also an inhibitor of succinic semialdehyde dehydrogenase, which indirectly increases GABA levels
It also has other means of increasing GABA levels and decreasing nerve stimulation that causes seizures

26
Q

What are the uses of Ethosuximide?

A

They are used to treat one absence seizures

27
Q

What is the method of action of ethosuxamide?

A

It blocks off T-type voltage gated Ca2+ channels in the synaptic knob

28
Q

What is serotonin also known as?

A

5-HT

29
Q

What is an SERT?

A

A seretonin transporter

30
Q

What is an SSRI?

A

A selective seretonin reuptake inhibitor

31
Q

What are some examples of SSRIs?

A

Citalopram
Escitalopram
Fluoxetine
Fluvoxamine
Paroxetine
Sertraline

32
Q

How many proteins form the Nicotinic Acetylcholine receptors?

A

5