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Cell Signalling > GPCRs and Enzyme-linked receptors (lect3) > Flashcards

GPCRs and Enzyme-linked receptors (lect3) Flashcards

1
Q

molecular switches.. two types ?

A

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

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2
Q

cAMP

A

3,5 Cyclic adenosine monophosphate

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3
Q

IP3

A

inositol 1,4,5 triphosphate

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4
Q

DAG

A

1,2 Diacylglycerol

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5
Q

cGMP

A

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

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6
Q

What do guanine nucleotide exchange factors do ?

A

GDP bound to G protein alpha subunit exchanged for for GTP

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7
Q

GTPase ?

A

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

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8
Q

What activates adenylyl cyclase ?

A

As subunit of G protein

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9
Q

what does adenylyl cyclase ?

A

converts ATP to cyclin AMP

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10
Q

What inhibits adenylyl cyclase ?

A

Ai subunit of G protein

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11
Q

how does the alpha subunit activate or inhibit adenylyl cyclase ?

A

phosphorylation ? conformational change ?

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12
Q

How are the effects of cAMP mediated ?

A

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

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13
Q

So what alpha subunit leads to protein kinase A

A

As subunit when its bound to GTP

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14
Q

what enzyme breaks down cAMP ?

A

Phosphodiesterases plus H2O

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15
Q

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

A

phosphodiesterases plus H2O

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16
Q

What does adrenaline do ?

A

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.

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17
Q

What activates phospholipase c-b?

A

Aq subunit when bound to GTP

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18
Q

What is produced by phospholipase c-b?

A

DAG and IP3

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19
Q

DAG? function

A

activates protein kinase C

20
Q

IP3? function

A

releases Ca2+ from endoplasmic reticulum

21
Q

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

A

yes

22
Q

How does IP3 increase intracellular ca2+ conc?

A

by activating ligand gated channels on the endoplasmic reticulum

23
Q

How are the effects of Ca2+ mediated ?

A

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

24
Q

can protein kinase A activate protein kinase 2 ?

A

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

25
Q

CamKII? name

A

Ca2+-calmodulin dependent protein kinase II

26
Q

What happens when calcium ions bind to calmodulin ?

A

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

27
Q

when is protein kinase fully active ?

A

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

28
Q

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

A

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

29
Q

how are Ca2+ terminated ?

A

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

30
Q

time domain of gene transcription ?

A

min.. caused by calcium signalling

31
Q

fertilisation.. proliferation.. hypertrophy

A

hr.. caused by calcium signalling

32
Q

conc of calcium that causes signalling ?

A

500nm

33
Q

why is diacylgylcerol bound to the membrane ?

A

because it’s a lipid

34
Q

what activates protein kinase C?

A

diacylgylcerol?

35
Q

what molecule does phospholipase c-b breakdown ?

A

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

36
Q

how are the effects of DAG mediated ?

A

by protein kinase C

37
Q

why is their Ca2+-DAG conspiracy ?

A

because apparently calcium enhances protein kinase C activity

38
Q

Receptor tyrosine kinases are activated by ?

A

Growth hormones

39
Q

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

A

true - example, receptor tyrosine kinases

40
Q

PDGF and FGF recptors are examples of ?

A

receptor tyrosine kinases

41
Q

what do receptor tyrosine kinases do upon activation ?

A

they auto phosphorylate

42
Q

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

A

they both auto phosphorylate

43
Q

what do receptor tyrosine kinases do when activated ?

A

auto phosphorylate and recruit other proteins

44
Q

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

A

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

45
Q

when monomeric G-protein Ras is activated what happens ?

A

a phosphorylation cascade that ends with MAPKinase

46
Q

example of cellular response to MAPKinase

A

mesoderm induction

Cell Signalling (5 decks)

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