W3- Lecture 13.3- Receptors (pharma) Flashcards

1
Q

Describe the structure of a kinase linked receptor (enzyme linked receptor)

A

Binding domain
Trans domain
Catalytic domain

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2
Q

Describe an enzyme linked reaction

A

Ligand binding
Receptor dimerisation
Activation of catalytic domain, tyrosine residues become phosphorylated

Accessory proteins bind to complex (e.g. Proteins containing SH2 domains)
Intracellular pathways are activated (kinase cascade)
Transcription factors are activated

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3
Q

Describe insulin activation of receptor tyrosine kinase

A

Insulin
binds to the α subunits of the insulin receptor
produces a conformational change in the receptor
activates tyrosine kinase in the β subunit, which causes autophosphorylation

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4
Q

What can activated tyrosine kinase phosphorylate ?

A

proteins or enzymes that are involved in the physiological actions of insulin (decrease in blood glucose) including protein kinases, phosphatases, phospholipases, and G proteins

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5
Q

Describe how receptor tyrosine kinase causes the suppression/synthesis of RNA

A

RTK activates a cascade of protein phosphorylation events that end up phosphorylation of transcription factors
Phosphorylated transcription factors enter the nucleus and bind to DNA
This activates or suppresses RNA for specific genes which contains transcription factors binding sites on their prompter region

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6
Q

How long do the effects last of RTK on gene expression ?

A

long lasting effects on cell activity (Hours/days/ weeks )

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7
Q

Name 4 classes of enzyme-linked reactions

A

Receptor tyrosine kinases (RTK)

Receptor serine/threonine kinases

Cytokine receptors

Guanylyl cyclase-linked receptors

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8
Q

How are the following different to RTK

Receptor serine/threonine kinases
Cytokine receptors
Guanylyl cyclase-linked receptors

A

RTK- has tyrosine kinase enzyme activity + growth factor receptor + insulin receptor

Receptor serine/threonine kinases-kinase phosphorylates serine residues on target proteins

Cytokine receptors-Lack their own tyrosine kinase activity but ligand binding causes receptors to activate cytosolic tyrosine kinases

Guanylyl cyclase-linked receptors-intrinsic enzyme activity causes cGMP (cyclic GMP) formation

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9
Q

Nuclear receptor
Type of protein
Found where
Structure

A

Globular protein
Found in cytosol
Binding domain -Transmembrane domain - DNA binding domain (zinc finger )

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10
Q

Name a drug that treats COVID and acts on the Nuclear receptors
Exact receptor
+ effect

A

dexamethasone
Acts on the glucocorticoid receptor agonist (steroidal)
Inflammation, immunosuppressant

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11
Q

Short description of how a Nuclear receptor acts

A

Ligand activated (transcriptional factors)
Receptor enters nucleus
Initiates gene transcription/ repression
Long term

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12
Q

Name two ligands that can bind to a nuclear receptor

Why ?

A

Steroid + thyroid hormones

They have to be able to pass the membrane

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13
Q

Name 1 nuclear receptor agonist

Action + use

A

Dexamethasone is a glucocorticoid receptor agonist, activation inhibits cycloxygenase-2 transcription and is a commonly used anti-inflammatory agent

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14
Q

Name one nuclear receptor antagonist

Action + use

A

Tamoxifen is an oestrogen receptor antagonist used in breast cancer therapy

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