GPCRs and Enzyme-linked receptors (lect3)

Question 1

molecular switches.. two types ?

Answer 1

signalling by phosphorylation .. and by GTP-Binding protein (G-proteins?)

Question 2

cAMP

Answer 2

3,5 Cyclic adenosine monophosphate

Question 3

IP3

Answer 3

inositol 1,4,5 triphosphate

Question 4

DAG

Answer 4

1,2 Diacylglycerol

Question 5

cGMP

Answer 5

3,5 cyclic guanine monophosphate (O sticking out of guanine)

Question 6

What do guanine nucleotide exchange factors do ?

Answer 6

GDP bound to G protein alpha subunit exchanged for for GTP

Question 7

GTPase ?

Answer 7

activated by factors GTP exchanged for GDP - GDP bound to G protien alpha subunit in resting state

Question 8

What activates adenylyl cyclase ?

Answer 8

As subunit of G protein

Question 9

what does adenylyl cyclase ?

Answer 9

converts ATP to cyclin AMP

Question 10

What inhibits adenylyl cyclase ?

Answer 10

Ai subunit of G protein

Question 11

how does the alpha subunit activate or inhibit adenylyl cyclase ?

Answer 11

phosphorylation ? conformational change ?

Question 12

How are the effects of cAMP mediated ?

Answer 12

by protein kinase.. cAMP dissociates catalytic from regulatory subunits OF the protien kinase A enzyme.. Catalytic subunits then phosphorylate substrates

Question 13

So what alpha subunit leads to protein kinase A

Answer 13

As subunit when its bound to GTP

Question 14

what enzyme breaks down cAMP ?

Answer 14

Phosphodiesterases plus H2O

Question 15

So what enzyme can down regulate the activity of protein kinase A ?

Answer 15

phosphodiesterases plus H2O

Question 16

What does adrenaline do ?

Answer 16

Activates cAMP pathway through B-adrenergic receptors in the heart… protein kinase activation.. phosphorylates several proteins increasing Ca2+ levels leading to increased force of contraction.

Question 17

What activates phospholipase c-b?

Answer 17

Aq subunit when bound to GTP

Question 18

What is produced by phospholipase c-b?

Answer 18

DAG and IP3

Question 19

DAG? function

Answer 19

activates protein kinase C

Question 20

IP3? function

Answer 20

releases Ca2+ from endoplasmic reticulum

Question 21

does IP3 and protien kinase A increase Ca2+ intracellular concentration ?

Answer 21

yes

Question 22

How does IP3 increase intracellular ca2+ conc?

Answer 22

by activating ligand gated channels on the endoplasmic reticulum

Question 23

How are the effects of Ca2+ mediated ?

Answer 23

by calmodulin - Ca2+ binding induces conformational changes and binding to target proteins

Question 24

can protein kinase A activate protein kinase 2 ?

Answer 24

yes.. i think ? by phosphorylating proteins which increase calcium conc thereby binding to calmodulin.. hence activating protein kinase 2

Question 25

CamKII? name

Answer 25

Ca2+-calmodulin dependent protein kinase II

Question 26

What happens when calcium ions bind to calmodulin ?

Answer 26

ca2+/calmodulin bind to protein kinase 2 which then undergoes auto-phosphorylation (ATP-ADP)

Question 27

when is protein kinase fully active ?

Answer 27

when a phosphate group and ca2+/calmodulin is bound to the protein kinase 2

Question 28

is protein kinase still active once ca2+/calmodulin dissociates from protein kinase 2 ?

Answer 28

yes because the phosphate is still bound.. and it takes longer to dissociate however protein kinase 2 is only partially (50-80%) active

Question 29

how are Ca2+ terminated ?

Answer 29

by calcium pumps (SERCA/PMCA) that calcium into the endoplasmic reticulum .. and Na+/Ca2+ exchange pumps (anti porter)

Question 30

time domain of gene transcription ?

Answer 30

min.. caused by calcium signalling

Question 31

fertilisation.. proliferation.. hypertrophy

Answer 31

hr.. caused by calcium signalling

Question 32

conc of calcium that causes signalling ?

Answer 32

500nm

Question 33

why is diacylgylcerol bound to the membrane ?

Answer 33

because it's a lipid

Question 34

what activates protein kinase C?

Answer 34

diacylgylcerol?

Question 35

what molecule does phospholipase c-b breakdown ?

Answer 35

PI 4,5 bisphosphate (PI(4,5)P2)

Question 36

how are the effects of DAG mediated ?

Answer 36

by protein kinase C

Question 37

why is their Ca2+-DAG conspiracy ?

Answer 37

because apparently calcium enhances protein kinase C activity

Question 38

Receptor tyrosine kinases are activated by ?

Answer 38

Growth hormones

Question 39

(enzyme-linked receptors) one polypeptide chain consists of extracellular receptor and intracellular catalytic subunit ? true or false

Answer 39

true - example, receptor tyrosine kinases

Question 40

PDGF and FGF recptors are examples of ?

Answer 40

receptor tyrosine kinases

Question 41

what do receptor tyrosine kinases do upon activation ?

Answer 41

they auto phosphorylate

Question 42

what does protein kinase C and receptor tyrosine kinases have in common ?

Answer 42

they both auto phosphorylate

Question 43

what do receptor tyrosine kinases do when activated ?

Answer 43

auto phosphorylate and recruit other proteins

Question 44

what happens when when mitogen(stimulus) binds to receptor tyrosine kinase ? think transducers

Answer 44

tyrosine kinase auto phosphorylates then Grb-2 is bound which grabs Sos (nucleotide exchange factor ) which activates Ras ( monomeric G-protien )

Question 45

when monomeric G-protein Ras is activated what happens ?

Answer 45

a phosphorylation cascade that ends with MAPKinase

Question 46

example of cellular response to MAPKinase

Answer 46

mesoderm induction