Receptors

Question 1

What is a receptor

Answer 1

A protein that recognises and creates a response to Environmental stimuli

Question 2

Receptor classes

Answer 2

Ligand gated ion channel(Inotropic)
G protein coupled receptors(metabotropic)
Kinase linked
Nuclear receptors

Question 3

Agonist

Answer 3

A chemical that binds to a receptor to activate it causing a biological response

Question 4

Active AR complex

Answer 4

Agonist+receptor= Active AR complex

causes a conformational change in the receptor causing agonist induced response

Question 5

Drug Agonist types

Answer 5

Full agonist-Receptor fully activated

Partial agonist-Activates receptor partially

Question 6

Affinity

Answer 6

The strength in attraction between the receptor and the agonist.
Smaller kd means higher affinity

Question 6

Efficacy

Answer 6

The maximum biological affect(Emax)

Partial agonist have low efficacy

Question 7

Potency

Answer 7

Potency is the concentration required to reach 50% of maximal effect(EC50)
Depends on the affinity

Question 8

Anxiolytic affect

Answer 8

When partial agonist binds it causes anxiolytic affect therefore having anti anxiety affect whereas a full agonist has sedation effect

Question 9

Inverse agonist

Answer 9

Binds to the same receptor as an agonist but induces an effect opposite to an agonist. It occurs to the receptors with constitutive activity(basal activity)

Question 10

Spare receptors

Answer 10

receptors that exist in excess of those required to produce a full effect

Question 11

Antagonist

Answer 11

A receptor that binds to a receptor but does not activate it

Question 12

Antagonist classes

Answer 12

Reversible-Competitive/non-competitive

Irreversible

Question 13

How to overcome competitive antagonist

Answer 13

Increasing agonist concentration or decreasing antagonist

Question 14

Competitive antagonist effect

Answer 14

Parallel shift to the right but no change to slope

Question 15

Schild Plot

Answer 15

Schild Plot is used to compare the different affects of the antagonist to the receptor.

Question 16

PA2

Answer 16

Shows how competitive an antagonist is
If there is a competitive agonist the slope should be 1
You can also tell how potent and effective the antagonist is
The smaller the PA2 the better it binds to the receptor

Question 17

Non-competitive antagonist

Answer 17

binds to the allosteric site

Haxamethonium blocks the ion channel of the nicotinic receptor

Question 18

Irreversible competitive antagonist

Answer 18

This antagonist dissociate very slow from the receptor
Increasing concentration does not increase response
Binds to the receptors using covalent bonds

Question 19

Irreversible competitive antagonist as non-surmountable

Answer 19

The inhibition is non-surmountable(The proportion of receptors occupied by the antagonist is lost by the agonist
Maximum response is decreased

Question 20

Specificity

Answer 20

Measures how well a drug can discriminate between different receptors. Low specificity can cause side effects as it causes responses to multiple receptors

Question 21

scatchard plot

Answer 21

We use a scatchard plot to find the Kd specificity

Question 22

KI

Answer 22

KI value is used to characterise the ability to inhibit agonist binding to the receptor

Question 23

GPCRS

Answer 23

G-protein-coupled receptors (GPCRs) are the largest and most diverse group of membrane receptors in eukaryotes

Question 24

Structure of GPCRS

Answer 24

There are Kinks in TM5-7 allowing for the conformational change The largest conformational change in TM6 moving outwards from the central TM3 BY 14A The small P(288 and 211) are proline residue they are hydrophobic residue and cause them to bend at these sites

Question 25

Ligands

Answer 25

Ligands bind to GDPR Ligands include light-sensitive compounds, odors, pheromones, hormones and neurotransmitters Lgands usually bind to extracellular sides

Question 25

Ligands

Answer 25

Ligands bind to GDPR Ligands include light-sensitive compounds, odors, pheromones, hormones and neurotransmitters Lgands usually bind to extracellular sides

Question 26

Forces in ligands

Answer 26

Ionic Hydrogen Hydrophobic Steric factors

Question 27

Receptor signal transduction

Answer 27

Agonist bind to receptor | Receptor conformational change via TM5,6,7

Question 28

GPCR signalling

Answer 28

G proteins relay signal from GPCR to secondary messengers

Question 29

G protein subunits

Answer 29

Alpha-Main role in activating effectors Beta Gamma

Question 30

Ga protein signalling

Answer 30

Ga activates cAMP cAMP then activates PKA PKA phosphorylates other substances

Question 31

GPCR desensitisation

Answer 31

When a receptor is constantly bound to by a agonist causing response to be lower overtime

Question 32

Homologous desensitisation

Answer 32

desensitisation caused by phosphorylation of GPCR via PKA