Cell signalling by G-protein coupled receptors

Question 1

What do G-protein coupled receptors respond to?

Answer 1

hormones
neurotransmitters
paracrine signals
odors
light

Question 2

what is the role of the receptor in the GPCR?

Answer 2

gives specificity

Question 3

what is the role of the G-protein in the GPCR?

Answer 3

transduces signal

Question 4

what is the role of the effector in the GPCR?

Answer 4

alpha and beta gamma subunits may provide different signals

Question 5

what do the intracellular signals generated by effector cells often regulate?

Answer 5

protein kinases

Question 6

what does adenylate cyclase activate?

Answer 6

protein kinase A (PKA)

Question 7

what does phospholipase C activate?

Answer 7

protein kinase C (PKC)

Question 8

how many pathways can a GPCR regulate?

Answer 8

Mulitple pathways

Question 9

what is the role of protein kinases?

Answer 9

provide the major mechanism for changing the activity of an existing protein

Question 10

what can protein kinases regulate?

Answer 10

-increase or reduce the activity of an enzyme
- turn a signal protein on or off
- change the location of a protein
- alter the interaction of a protein with other molecules

Question 11

what is post-translational modification?

Answer 11

the regulated addition of a small molecule
- most often the addition of a phosphate
- adds a large negative charge

Question 12

what is the result of post-translational modification?

Answer 12

will cause the folded protein to adjust its shape

Question 13

what is phosphorylation?

Answer 13

transfer a phosphate from ATP to the target protein

Question 14

what is the role of protein kinases?

Answer 14

adds phosphates

Question 15

what is the role of protein phosphatases?

Answer 15

removes phosphates

Question 16

how are protein kinases categorized?

Answer 16

after their amino acid target

Question 17

how is protein kinase A activated?

Answer 17

-PKA exists as an inactive complex with its regulatory subunits
-cAMP binds to the regulatory subunits
-causes them to dissociate
-releasing the active kinase

Question 18

where is inactive PKA located?

Answer 18

at the cell membrane

Question 19

how do protein kinases increase the expression of a protein via transcription factors?

Answer 19

changes the amount of a specific protein in a cell

Question 20

how do protein kinases change the activity of existing protein?

Answer 20

increase the activity of an enzyme

Question 21

what is tyrosine hydrozylase?

Answer 21

carries out the first and rate-limiting step in catecholamine production

Question 22

what are some different catecholamines?

Answer 22

dopamine
noradrenaline
adrenaline

Question 23

where is dopamine synthesized?

Answer 23

in nerve terminals

Question 24

when is dopamine released?

Answer 24

in response to nerve stimulation

Question 25

how does phosphorylation effect dopamine synthesis?

Answer 25

phosphorylation reduces the negatibe feedback by dopamine

Question 26

where can Tryosine hydroxylase be phosphorylated?

Answer 26

at 4 different sites

Question 27

where do kinases act on tryosine hydroxylase?

Answer 27

different kinases act on different sites
Different sites ahve different effects on activity
-the order of phosphorylation matters