l. Lecture (Feb. 8th) Slide Deck PDF document

Question 1

Which pathway is most RTKs and cytokine kinase receptors activated by?

Answer 1

Ras/MAP kinase pathway

Question 2

What is the Ras protein?
a) GEF
b) GTPase
c) GAP
d) enzyme
e) b and c

Answer 2

b

Question 3

Activating Ras stimulates the formation of the ________ cascades which involves the activation of ______ kinases

Answer 3

kinase, MAP

Question 4

Describe the 7 steps to the MAP kinase pathway using these terms; ligand, RTK, monomer, dimerize, autophosphorylating, kinase domain, activation loop, tyrosine residues, SH2, SH3, GRB2, GEF, Sos, GTP, GDP, G-protein, Ras, Raf, GAP, 14-3-3, hydrolysis, GTPase, MAPKKK, MAPKK, MAPK, ERK, MEK, phosphorylate, P90-RSK, SRF, transcription factor, SRE, TCF,

Answer 4

1. 2 ligands bind to the RTK monomers that causes them to dimerize resulting in the autophosphorylation of the intracellular kinase domains due to the removal of the activation loop
2. Once the tyrosines residues are phosphorylated the SH2 domain of the GRB2 protein associates w/them while its SH3 domains bind to the GEF Sos activating it
3. Sos associates and exchanges the bound GDP w/ GTP on the G-protein Ras activating it
4. Ras then activates Raf which phosphorylates the inhibitor 14-3-3. Also, Raf acts as a GAP that aids the GTPases to hydrolyze the bound GTP to GDP in the Ras causing it to disassociate from Raf
5. the kinase Raf is also known as MAPKKK phosphorylates MEK/MAPKK which phosphorylates ERK/MAPK
6. the kinase ERK phosphorylates P90- RSK which translocates into the nucleus and phosphorylates the SRF transcription factor bound to the SRE gene. Followed by ERK translocating into the nucleus itself and phosphorylating the transcription factor TCF also bound to the SRE gene
7. regulation of SRE gene expression

Question 5

a) What are the two domains associated w/ GRB2?
b) What do they associate with?
c) What dictates where they will bind?

Answer 5

1. SH2 -> phosphorylated tyrosines w/in the intracellular kinase region of the RTK
2. SH3 -> the proline-rich motif of the Sos/GEF protein activating it
   c) the AA that surrounds the phosphorylated residue

Question 6

What are all of these proteins also known as
a) Sos
b) Ras
c) Raf
d) MEK
e) ERK
f) 14-3-3

Answer 6

a) GEF - guanine nucleotide exchange factor
b) G-protein
c) MAPKKK or GAP (GTPase accelerating protein)
d) MAPKK
e) MAPK
f) inhibitor

Question 7

Within the MAP pathway, what are the 3 proteins that inhibit its transduction? Explain each.

Answer 7

1. activation loop = blocks the kinase domains of a protein from doing phosphorylation
2. 14-3-3 = an inhibitor protein that prevents Raf/MAPKKK from phosphorylating MEK/MAPKK

Question 8

a) What does GRB2 stand for?
b) what does it recognize
c) what does it activate

Answer 8

a) growth factor receptor binding protein 2
b) the phosphorylated tyrosine residues on the kinase region of the RTK
c) the Sos/GEF

Question 9

T or F - all proteins w/ an SH3 domain recognize and bind to the tyrosine residues in a kinase receptor

Answer 9

F - phosphorylated tyrosine residues

Question 10

T of F - Raf acts as a GTPase as it hydrolysis the GTP to GDP of the G-protein Ras causing it to disassociate from it

Answer 10

F - Raf is an aid to GTPase also known as GAP (GTPase accelerator protein)

Question 11

Match the following
a) p90-RSK
b) ERK/MAPK
1. TCF
2. SRF
3. SRE

Answer 11

a) 2 + 3
b) 1 + 3

Question 12

All of the following are MAP kinases except
a) MEK
b) Ras
c) ERK
d) Raf
e) they are all MAP kinases

Answer 12

b

Question 13

Which of the following is a gene promoter?
a) SRE
b) SRF
c) TCF
d) ERK

Answer 13

a

Question 14

All of the following are found w/in the nucleus except
a) TCF
b) SRF
c) SRE
d) P90-RSK

Answer 14

d

Question 15

T or F - Ras is a GTPase protein

Answer 15

T - As after some time the GTP w/in an activated G-protein will eventually hydrolyze into GDP all by itself making the G-protein itself a GTPase

Question 16

We all know that RTKs activate the MAPK signal transduction pathway but what other pathway does it activate?

Answer 16

the phosphoinositide signaling pathway PI-3 kinase

Question 17

RTKs and cytokine receptors activate the ________, which produces _________, which in turn binds to ______ domains in various proteins to form signaling complexes that active another kinase, __________

Answer 17

PI-3 kinase, PI 3-phosphates, PH, Protein kinase B (PKB)

Question 18

PI-3 kinase is a kinase that recognizes the phosphorylated tyrosine residues w/in the kinase region of the RTK. In order to do this which domain must it contain?

Answer 18

SH2

Question 19

a) What does PI-3K phosphorylate?
b) What does that phosphorylation generate?

Answer 19

a) PI1 or PI2
b) PI-3 phosphates (PI2 or PI3)

Question 20

a) What kinase does PI2 associate w/?
b) What domain does it recognize and bind w/ specifically?
c) What does associating cause?

Answer 20

a) PKB (protine kinase B)
b) PH domain
c) relocates the PKB to the mem and partially activates it

Question 21

a) What are the 2 kinases that fully activated PKB? Which of them is also a membrane-bound kinase?
b) how do they do this?

Answer 21

a)
1. PDK1 (membrane-bound kinase)
2. PDK2
b) by moving the activation loop that is blocking the kinase domain of the PKB

Question 22

T or F - PI2 paired w/ PDK2 fully activates the PKB

Answer 22

F - PI2, PDK1 and PDK2 are needed

Question 23

Label the following
a) PDK1
b) PDK2
c) PI 3,4-bisphosphate (PI2)
d) PKB

Answer 23

a) pink
b) blue
c) yellow
d) green

Question 24

Describe the steps to the phosphoinositide signaling pathway (PI-3Kinase) using the following terms; ligand, RTK, monomer, dimerize, autophosphorylation, kinase, activation loop, SH2, PI3K, tyrosine residues, PI1, PI2, PI-3 kinase phosphate, PI 4-phosphate, PI 3,4-bisphosphate, PH domain, PKB, membrane-bound, PDK1, PDK2, cell met, cell growth, gene expression

Answer 24

1. 2 ligands bind to each RTK monomer causing them to dimerize. Resulting in the autophosphorylation of the intracellular kinase region due to the activation loop being moved
2. The SH2 domain of the PI3K recognizes and binds to the phosphorylated tyrosine residues on the RTK
3. PI3K phosphorylates PI1 or PI2 to generate PI-3 phosphates
4. the PI-3 kinases phosphorylate PI 4-phosphate to PI 3, 4-bisphosphate
5. the PH domain of the PKB recognizes and binds to the membrane-bound PI 3,4-phosphate partially activating it
6. the membrane-bound PDK1 and cytosolic PDK2 phosphorylate the PKB fully activating it as it activation loop has now been moved
7. PKB and other kinases cause a cascade that results in cell metabolism, cell growth, and gene expression