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PHAR0002 > RTKs > Flashcards

RTKs Flashcards

1
Q

What is a dimer?

A

Molecule formed by 2 identical molecules linked together

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2
Q

What does ‘Erlotinib’ do?

A

Inhibits EGFRs (epidermal growth factor receptors)

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3
Q

What are the 3 domains of RTKs?

A
  1. Extracellular ligand-binding domain
  2. Transmembrane region
  3. Intracellular kinase domain
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4
Q

What are the 2 major types of RTK?

A

Epidermal growth factor receptor
Fibroblast growth factor receptor

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5
Q

What are RTKs?

A

Receptor tyrosine kinases

A type of plasma membrane receptor which are involved in signal transduction pathways in cells.

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6
Q

What are kinases?

A

Enzymes that catalyse the transfer of phosphate groups

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7
Q

What are fibroblast growth factor receptors associated with?

A

Angiogenesis (the process by which new blood vessels form from pre-existing ones)

Bone healing

Embryonic development

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8
Q

What are epidermal growth factor receptors associated with?

A

Signalling in the NS

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9
Q

Why is research being done into the use of RTKs as anti-cancer drugs?

A

Because they regulate cell growth & division and cancer is caused by uncontrolled cell growth & division

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10
Q

What is the function of RTKs?

A

Regulate cell growth & division

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11
Q

What do tyrosine kinases do?

A

Catalyse the transfer of phosphate groups from ATP to the amino acid tyrosine on a substrate protein

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12
Q

What is Erlotinib used in?

A

Recommended by NICE as a treatment option for non-small cell lung cancer that has progressed
Unfortunately, it has a modest effect

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13
Q

Describe diabetes mellitus type 1

A

Usually begins in childhood (juvenile onset diabetes)

Caused by a severe under-production of insulin

Often associated with destruction of beta cells of the pancreas (autoimmune)

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14
Q

What is diabetes mellitus type 1 also called?

A

Insulin-dependent diabetes mellitus (IDDM)

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15
Q

Describe diabetes mellitus type 2

A

Usually has a late onset (maturity onset diabetes)

Characterised by an impaired response to insulin in the body & impaired insulin secretion

Weight loss & diet control can be effective treatments

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16
Q

What is diabetes mellitus type 2 also called?

A

Non-insulin dependent diabetes (NIDDM)

17
Q

Describe the action of RTK activation (5 steps)

A
  1. Ligand binds to RTK - causing dimerisation
  2. Autophosphorylation - intracellular kinase domains phosphorylate each other
  3. Activated RTK interacts with (provides binding sites for) intracellular signalling proteins (e.g. SH2 domain protein)
  4. These proteins initiate a signalling cascade
  5. Which leads to a cellular response (depends on ligand and cell that the RTK is on)
18
Q

What are 3 examples of RTKs?

A

Epidermal Growth Factor Receptor (EGFR)

Insulin Receptor (IR)

Fibroblast Growth Factor Receptor (FGFR)

19
Q

What is the danger of undiagnosed and untreated diabetes mellitus?

A

Without necessary supply of energy (from glucose breakdown), the body starts to breakdown fats, leading to KETOACIDOSIS (blood becomes more acidic than the body tissues)

This can be fatal

20
Q

What is unique of the structure of the insulin RTK?

A

‘A dimer of dimers’

It is made up of 2 sets of dimers:
1. 2 identical alpha-subunits
2. 2 identical beta-subunits

Dimers linked together through disulfide bonds to form a tetramer

21
Q

Describe the mechanism of action of RTKs

A
  1. Most RTK receptors are present as individual monomers embedded in the plasma membrane, some exist as inactive dimers
  2. Agonist binds to the ligand-binding sites in the extracellular domain
  3. Causes dimerisation (2 receptor monomers associate with each other to form a dimer or the agonist binds to 2 monomers at the same time)
  4. When the dimers form, changes in the intracellular regions of the receptor activate their kinase domains
  5. Autophosphorylation of the dimer occurs (ie. Phosphorylation by the opposite kinase dimer)
  6. This produces phosphotyrosine residues which act as specific binding sites for downstream signalling molecules (proteins)
  7. These proteins contain binding domains which interact with the kinase domain (ie. SH2 or PTB domains)
  8. Binding of a protein via an SH2 or PTB domain activates further steps in the signalling pathway - causing a cellular response
22
Q

What is diabetes mellitus characterised by?

A

Hyperglycaemia (high BGC)

23
Q

What is the effect of diabetes mellitus on urine production?

A

Increased volume of urine is produce as excess glucose is filtered out into urine and draws water out with it

PHAR0002 (20 decks)

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