Tissues 11: Signalling between cells II

Question 1

What are ionotropic receptors

Answer 1

a

Question 2

How do iontropic receptors function

Answer 2

A ligand binds to the receptor causing the ion permeable pore to open allowing molecules to traverse the membrane

Question 3

What is a G-protein coupled receptor

Answer 3

a

Question 4

What is an enzyme linked receptor

Answer 4

a

Question 5

What is an intracellular receptor

Answer 5

a

Question 6

What are the signal transduction events of an iontropic receptor

Answer 6

a

Question 7

Give some examples of ionotropic receptors

Answer 7

Nicotinic Acetycholine receptor
Ligand: Acetylcholine(ACh)
Location: Skeletal muscle
Physiological effect: Muscle contraction

GABA(a)
Ligand: gamma-amino butyric acid(GABA)
Location: Neuronal
Physiological effect: Decrease neuronal excitability

Question 8

How do G proteins work

Answer 8

7-TM receptor and heterotrimeric G-protein are inactive

Ligand binding on outside causes change conformation of receptor

Unassociated G-protein binds to receptor
GDP is exchanged for GTP

G-protein dissociates into two active components
alpha subunit
betagamma subunit

Each binds to their target proteins

(add photo)

Internal GTPAse activity on alpha subunit dephosphorylates GTP

alpha subunit dissociayes from target protein

Question 9

What is a hetertrimeric protein

Answer 9

a

Question 10

What does 7-TM stand for

Answer 10

a

Question 11

Which subunits stay together in a heterotrimer

Answer 11

a

Question 12

How many main isoforms are there of the G alpha subunit

Answer 12

3

Question 13

What are the 3 G alpha subunits and what are the differences

Answer 13

G alpha s - stimulates adenylyl cyclase
G alpha i - inhibits adenylyl cyclase
G alpha q - stimulates phospholipase C

Question 14

What does atropine do

Answer 14

a

Question 15

What do G alpha s subunits do

Answer 15

a

Question 16

What do G alpha i subunits do

Answer 16

a

Question 17

What do G alpha q subunits do

Answer 17

a

Question 18

Give examples and effects of Galpha subunits

Answer 18

a

Question 19

Why are G protein coupled receptors so important

Answer 19

a

Question 20

What is the generic mechanism of action for enzyme linked receptors

Answer 20

Ligand binding - receptor clustering

Receptor clustering activates enzyme activity within cytoplasmic domain

Enzymes phosphorylate receptor

a

Question 21

Give some examples of enzyme-linked signal transduction

Answer 21

Insulin receptor (CD220 antigen)
Ligand: Insulin
Physiolgical effect: Glucose uptake
Enzyme: tyrosine kinase

ErbB receptors 
Ligand: Epidermal growth factor 
Transforming growth factor beta 
Physiological effect: Cell growth and Proliferation
Enzyme: tyrosine kinase

Guanylyl-cyclase linked receptors

NPRA
Ligand: Atrial/Brain natiriuetic peptide
Physiological effects

a

Question 22

Which processes are enzyme-linked signal transductions generally linked to

Answer 22

a

Question 23

How many types of intracellular receptors are there

Answer 23

2

Question 24

How do type I intracellular receptors work, where are they located and give their structure

Answer 24

Cytoplasmic
Located within cystolic compartment
Associated with chaperone molecules
(heat shock proteins, hsp)
Hormone binds to receptor - hsp dissociates
2 hormone bound receptors form a homodimer
The hormodimer translocates to the nucleus - binds to DNA

Question 25

Produce an order in terms of time of which signalling is fastest and slowest and give reasons

Answer 25

a

Question 26

How do type II intracellular receptors work, where are they located and give their sturcture

Answer 26

a

Question 27

Give examples of type I intracellular receptors

Answer 27

Gluc

Question 28

Give examples of type II intracellular receptors

Answer 28

a