L3 - How Drugs Work - Part 2 Flashcards Preview

Y2 - Normal function of GI tract > L3 - How Drugs Work - Part 2 > Flashcards

Flashcards in L3 - How Drugs Work - Part 2 Deck (17)
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1
Q

how does direct opening of ion channels work?

A
  • in this case receptor protein is an ion channel
    • protein that forms a pore in plasma membrane through which a specific type of ion can pass
  • open/closed depending of the presence of the specific agonist
  • binding of agonist results in a conformation change in the protein, which then opens
  • ions flow through channel down conc gradient
2
Q

for the agonist acetylcholine, what is the recptor and the channel

A
  • receptor
    • nicotinic chlonergic
  • channel
    • opens cation channels
    • mainly Na+
3
Q

How do enzyme receptors work

A
  • mainly transmembrane proteins which often psses enzyme activity
  • they have a ligand binding domain on the outer face of the plasma membrane
  • also have a catalytic or enzymatic domain of the inner face of the plasma membrane
  • strimulation of this type of receptor by an agonist increases the receptors catalytic activity
4
Q

domain

A

a distinct region of a complex molecule or structure

5
Q

tyrosine kinase receptors

A
  • class of enzyme-linked receptors
  • activation of the recptor by the agonist causes the trasnfer of a phosphate group onto specifc amino acids in the recptor itself
  • this results in the recruitment of proteins from the cytosol
    • become ‘scaffolded’ to the receptor
  • this scaffold transmits the signalling information to the cell
6
Q

what type of recptor is the insulin receptor, what is the agonist, what physiological effects does it have, what disease does it treat

A
  • tyrosine kinase receptor
  • agonist is insulin
  • physiological effect is glucose uptake
  • disease is diabetes
7
Q

What are the 3 protein components of G protein-coupled receptor signalling

A
  • 7 transmembrane receptor
  • G portein (‘switch)
    • GTP bound = active/on
    • GDP bound= inactive/off
8
Q

What are GTP and GDP

A
  • GTP
    • guanosine triphosphate
  • GDO
    • guanosin diposphate
9
Q

G protein-coupled receptor singalling

what do components 1 and 2 do

A
  • component 1
    • each receptor (GPCR) binds its specific agonist
    • e.g. glucagon binds to glucagon receptors
  • component 2
    • the G-protein (guanine nucleotide-binding regulatory protein) acts as a molecular switch
    • the G-protein is associated with GTP, off when associated with GDP
    • swithches itself and the system off
10
Q

G-protein

A

guanine nucleotide-binding regulatory protein

11
Q

what is the third component

A
  • effector enzymes
  • produce secondary messengers
12
Q

secondary messengers

A
  • bind to specific target proteins within the cell to change the cell’s physiology
  • usually protein kinases or IP3 receptors
13
Q

adenyl cyclase

A
  • catalyses conversion of ATP (adenosine triphosphate) to cAMP (cyclic edenosine monophosphate)
14
Q

phospholipase C

A
  • cuts the plasma membrane lipid phosphatidylinositol bisphosphate into DAG (diacylglycerol) and IP3 (inositol trisphosphate)
15
Q

cGMP phosphodiesterase

A
  • effector enzyme
  • breaks down cGMP (cyclic GMP, cyclic guanosine monophosphate)
16
Q

How does GPCR signalling work (GG protein-coupled receptor signalling)

ACTIVATION

A
  • agonist activation of receptor induces its 3d or conformational shape
    • enabling it to interact with a G protein
  • the G protein loses GDP and gains GTP
  • G protein becomes switched on
  • activated G protein interacts with the effector enzyme and increases its catalytic activity
    • the effector enzyme produces specific ‘second messenger’ molecules
    • these alter the biochemical machinery inside the cell by interacting with their specific target molecules
      • which either phosphorylate other specific protein or releases intracellular stores of Ca2+
17
Q

How GPCR signlaling works

deactivation

A
  • agonist dissociates from receptor
  • G protein’s own GTPase activity convers the bound GTP and GDP and the G protein becomes switched off
  • G protein interaction with the effector enzyme ceases and the effector enzyme activity returns to normal
  • the ‘second messenger’ molecules are broken down and their target proteins are no longer activatied