Drug transporters

Question 1

Coupling

Answer 1

Links the extra cellular and intercellular domain

Question 2

Ligand gated ion channel receptor

Answer 2

Central pore surrounded by its subunits. The extra cellular domain is the ion selectivity domain, for ligand binding. It has a transmembrane helices and intercellular domain called the gating domain that controls ion influx.

Question 3

Examples of ligand gated ion channels

Answer 3

Nicotinic receptors and GABA receptors (pain)

Question 4

Ligand gated ion channel activation

Answer 4

Ligand binds to extracellular allosteric site which bc aides a conformational change to the intracellular gating domain to open or close. It is the fastest channel.

Question 5

Inhibition of ligand gated ion channels

Answer 5

It has multiple almost eric sites. Blocking gating domain, preventing closing of gating domain or blocking the ion selectivity domain.

Question 6

G protein coupled receptors

Answer 6

Consists of extra cellular loops. 7 transmembrane alpha helices and heterotrimeric G protein intracellular loop with an alpha subunit to link to the effector amplifier enzyme or ion channels.

Question 7

Examples of G protein coupled receptors

Answer 7

Muscarinic receptors and adrenoreceptors

Question 8

Difference between nicotinic and muscarinic receptors

Answer 8

Muscarinic and Nicotinic receptors both allow aCTH to bind. Muscarinic receptors are G protein coupled receptors which induce protein kinase activation for gene expression. Nicotine receptors are ligand gated ion channel receptors which become voltage gated Na+ channels following aCTH binding.

Question 9

Kinase receptor

Answer 9

Two transmembrane proteins linked by ligand binding which triggers dimerisation.

Question 10

Activation of kinase receptor

Answer 10

Following dimerisation, it triggers activation of protein kinase which autophosphorylates tyrosine protein residues on the intracellular catalyctic domain. This allows binding to the G protein. Ras GTPase -> RAF GTPase -> map kinase kinase kinase -> map kinase kinase -> map kinase. Map kinase affects ATP hydrolysis.

Question 11

JAKS/ STATS pathway

Answer 11

Regulation of inflammatory mediator transcription.

Question 12

Intracellular receptor

Answer 12

Cytoplasmic receptor and nuclear receptor

Question 13

Cytoplasmic receptor

Answer 13

Nuclear receptor with homodimer interactions. It responds to endocrine signals.

Question 14

Nuclear receptors

Answer 14

Intracellular receptors with heterodimer interactions that respond to lipid signals. Forms dimer with retinoid x receptor.

Question 15

Opioid addiction agonist

Answer 15

Methadone which is an analgesic that reduces withdrawal to block high. Effectivity increases with each dose.

Question 16

Opioid withdrawal antagonist

Answer 16

Naltrexone creates negative conditioning by targeting positive effects of opioid use. Quick onset but reduced effectivity over time.

Question 17

Cell adhesion molecules

Answer 17

Allows linking to occur to gain access to adjacent cells. It has a non polar internal acyl chain and polar external head.

Question 18

Types of CAMs

Answer 18

Cadherin, intestine and selectins

Question 19

Cadherin

Answer 19

Ca2+ dependent to form homophilic interactions with adjacent cell’s cadherin. Internal chain is connected to actin to access cell cytoskeleton.

Question 20

Integrins

Answer 20

Alpha and beta chain disassociate to form homophilic interactions. Acts as a receptor for cell signalling.

Question 21

Selectins

Answer 21

Ca2+ dependent lectin proteins which form heterophilic interactions with only sugar molecules.

Question 22

Types of junctions

Answer 22

Adheren, occluding, desmosomes and gap junctions.

Question 23

Anchoring/adheren junctions

Answer 23

Homophilic interactions between cadheren and integrin which create a continuous belt. It anchors epithelial cells and provided a mechanical link to the cytoskeleton.

Question 24

Occluding junctions

Answer 24

Seals cells together by creating a tight paracellular cleft in the epithelia to prevent leakage. Formed of highly conserved claudin and lowly conserved occludins.