Week 2 - Recap and Quiz

Question 1

What type of receptor do adrenaline/noradrenaline ligands bind to?

Answer 1

Cell Surface GPCRs

Question 2

Which adrenergic receptor is responsible for mediating the broncho-dilatory effects of adrenaline

Answer 2

b2 adrenergic receptor

Question 3

in respiratory tract smooth muscle cells, which heterotrimeric G protein complex does this receptor couple to?

Answer 3

Gs

Question 4

What membrane-associated effector does this heterotrimeric G protein complex regulate?

Answer 4

Andenylyl cyclase

Question 5

Intracellular levels of what second messenger are regulated by this effector

Answer 5

cAMP (levels increase)

Question 6

What ‘downstream’ signalling molecule is activated as a consequence?

Answer 6

Protein Kinase A

Question 7

How does activated PKA cause the broncho-dilatory effect of adrenaline?

Answer 7

Inhibits MLCK

Question 8

Which adrenergic receptor is responsible for mediating the vasoconstrictive effects of adrenaline?

Answer 8

a1 adrenergic receptor

Question 9

In the vasculature, smooth muscle a1 adrenergic receptors couple to which heterotrimeric G protein complex

Answer 9

Gq

Question 10

What membrane-associated effector does this heterotrimeric G protein complex regulate

Answer 10

Phospholipase C

Question 11

Intracellular levels of what second messenger are regulated by the effector phospholipase C?

Answer 11

IP3 and DAG (levels increase)
Ca2+ (levels increase)

Question 12

What ‘downstream’ signalling molecule is activated as a consequence of IP3, DAG and Ca2+ levels increasing?

Answer 12

CRAC
Protein Kinase C

Question 13

If expression of a MAPKKK enzyme is lost due to homozygous mutation (that introduces a premature STOP codon) in the relevant MAPKKK gene:

Answer 13

MAPK cannot be activated regardless of the presence of ligand.

Question 14

Of the following second messengers which one(s) are hydrophobic?

Question 15

_________rely on _________ such as Ca2+, cAMP and DAG to activate or inactivate a variety of pathways within the cell

Question 16

Place the following events in the correct order as they occur after the dissociation of Gα/β/γ complexes:
cAMP is produced
phosphate groups are attached to serine/threonine residues
cAMP binds to a protein kinase
phosphodiesterases breakdown cAMP
Gα binds to adenylyl cyclase

Question 17

The enzyme that catalyzes the hydrolysis of PI(4,5)P2 into two second messenger molecules, is called:

Question 18

The addition of a (PO4)3- group to a protein is a common form of protein modification. This chemical modification is called ________.

Question 19

In the MAPK signalling pathway, protein phosphorylation serves to ________?

Answer 19

• Activate the next component in the signalling pathway
• Amplify the original signal as it is transmitted through the signalling pathway

Question 20

Which of the following are the most commonly phosphorylated amino acids in mammals?

Question 21

A signal peptide:

Answer 21

May be responsible for targeting the protein to the Golgi

Question 22

Ubiquitin is added to:

Answer 22

The side chain of Lysine residues on the target protein via an amide bond

Question 23

Some mitogen receptors activate a protein kinase cascade, which includes the participation of multiple enzymes, to effect a change in gene expression. Which of the following statements about a protein kinase cascade are true?

Answer 23

protein kinase cascades are important components of membrane signalling. The signal is amplified, target proteins for kinases determine responses, and mutations in signalling pathways are a significant part of cancer cell growth