TK and nuclear hormone receptors

Question 1

Tyrosine kinase has a double extracellular region (N terminal). True or false?

Answer 1

False - single extracellular region

Question 2

The extracellular region includes binding site for ____________

Answer 2

chemical messenger

Question 3

It has a single hydrophobic region that traverses the membrane as an alpha helix of ____ turns

Answer 3

7

Question 4

The C-terminal chain is inside the cell membrane and acts as a _________

Answer 4

catalytic binding site

Question 5

TK receptors have a dual role. They act as _______ and _______

Answer 5

enzymes

receptors

Question 6

In the resting state, does the receptor have any catalytic activity?

Answer 6

No - the active site is hidden

Question 7

What happens when the ligand binds to the receptor?

Answer 7

The receptor changes shape and reveals the active site on the C-terminal chain - phosphorylation can now occur

Question 8

What is required to supply the phosphate?

Answer 8

ATP

Question 9

EGF is a bivalent ligand. What is meant by this?

Answer 9

It can bind two receptors at the same time

Question 10

What happens when EGF binds receptors?

Answer 10

Results in receptor dimerisation and activation of enzyme activity

Question 11

Phosphorylation can take place even if dimerisation doesn’t occur. True or false?

Answer 11

False

Question 12

Some insulin receptors already exists as dimers or trimers and only require the binding of a ligand. True or false?

Answer 12

False - exists as dimers or tetramers

Question 13

The insulin receptor is a homotetrameric complex which acts as a TK receptor, True or false?

Answer 13

False - heterotetrameric

Question 14

What is the difference between TK receptors and TK linked receptors?

Answer 14

TK linked receptors require an extra step because they do not have catalytic activity in their C terminal chain. Ligands can bind and dimerise and then activate a TK enzyme from the cytoplasm (extra step)

Question 15

Once the kinase receptor has been phosphorylated, the phospho-tyrosine groups acts as binding sites for ____________

Answer 15

signalling proteins

Question 16

signalling proteins cannot become phosphorylated. True or false?

Answer 16

False - they can become phosphorylated and act as further binding sites

Question 17

What determines the type of signalling that takes place?

Answer 17

The protein that has managed to bind to the kinase receptors

Question 18

Some growth factors activate _________ leading to calcium release

Answer 18

phospholipase C

Question 19

Some TK receptors can catalyse the formation of ____ from GTP

Answer 19

cGMP

Question 20

cGMP opens _______ channels in the kidney which promote the excretion of _______

Answer 20

sodium

sodium

Question 21

TK receptors are more important than GPC receptors. True or false?

Answer 21

False - second most important drug targets after GPC

Question 22

Which human diseases is kinase activity implicated?

Answer 22

Cancer
Rheumatoid arthiritis
Asthma
Psoriasis

Question 23

How can modulation of kinase activity be achieved?

Answer 23

Inhibition of phosphorylation activity by blocking ATP binding
Disruption of protein-protein interactions
Down-regulation of kinase gene expression

Question 24

Which drug inhibits abnormal kinase in chronic myeloid leukaemia?

Answer 24

Imatinib mesylate

Question 25

Which two drugs target ATP binding to EGFR (which is overexpressed in tumours)?

Answer 25

Gefitinib

Erlotinib

Question 26

Which two drugs block the receptor protein kinase?

Answer 26

Cetuximab

Panitumumab

Question 27

Which drug blocks a ligand from binding to receptors?

Answer 27

Bevacizunam