l. Lecture (Feb. 8th) Slide Deck PDF document Flashcards
Which pathway is most RTKs and cytokine kinase receptors activated by?
Ras/MAP kinase pathway
What is the Ras protein?
a) GEF
b) GTPase
c) GAP
d) enzyme
e) b and c
b
Activating Ras stimulates the formation of the ________ cascades which involves the activation of ______ kinases
kinase, MAP
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,
- 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
- 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
- Sos associates and exchanges the bound GDP w/ GTP on the G-protein Ras activating it
- 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
- the kinase Raf is also known as MAPKKK phosphorylates MEK/MAPKK which phosphorylates ERK/MAPK
- 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
- regulation of SRE gene expression
a) What are the two domains associated w/ GRB2?
b) What do they associate with?
c) What dictates where they will bind?
- SH2 -> phosphorylated tyrosines w/in the intracellular kinase region of the RTK
- SH3 -> the proline-rich motif of the Sos/GEF protein activating it
c) the AA that surrounds the phosphorylated residue
What are all of these proteins also known as
a) Sos
b) Ras
c) Raf
d) MEK
e) ERK
f) 14-3-3
a) GEF - guanine nucleotide exchange factor
b) G-protein
c) MAPKKK or GAP (GTPase accelerating protein)
d) MAPKK
e) MAPK
f) inhibitor
Within the MAP pathway, what are the 3 proteins that inhibit its transduction? Explain each.
- activation loop = blocks the kinase domains of a protein from doing phosphorylation
- 14-3-3 = an inhibitor protein that prevents Raf/MAPKKK from phosphorylating MEK/MAPKK
a) What does GRB2 stand for?
b) what does it recognize
c) what does it activate
a) growth factor receptor binding protein 2
b) the phosphorylated tyrosine residues on the kinase region of the RTK
c) the Sos/GEF
T or F - all proteins w/ an SH3 domain recognize and bind to the tyrosine residues in a kinase receptor
F - phosphorylated tyrosine residues
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
F - Raf is an aid to GTPase also known as GAP (GTPase accelerator protein)
Match the following
a) p90-RSK
b) ERK/MAPK
1. TCF
2. SRF
3. SRE
a) 2 + 3
b) 1 + 3
All of the following are MAP kinases except
a) MEK
b) Ras
c) ERK
d) Raf
e) they are all MAP kinases
b
Which of the following is a gene promoter?
a) SRE
b) SRF
c) TCF
d) ERK
a
All of the following are found w/in the nucleus except
a) TCF
b) SRF
c) SRE
d) P90-RSK
d
T or F - Ras is a GTPase protein
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
We all know that RTKs activate the MAPK signal transduction pathway but what other pathway does it activate?
the phosphoinositide signaling pathway PI-3 kinase
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, __________
PI-3 kinase, PI 3-phosphates, PH, Protein kinase B (PKB)
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?
SH2
a) What does PI-3K phosphorylate?
b) What does that phosphorylation generate?
a) PI1 or PI2
b) PI-3 phosphates (PI2 or PI3)
a) What kinase does PI2 associate w/?
b) What domain does it recognize and bind w/ specifically?
c) What does associating cause?
a) PKB (protine kinase B)
b) PH domain
c) relocates the PKB to the mem and partially activates it
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?
a)
1. PDK1 (membrane-bound kinase)
2. PDK2
b) by moving the activation loop that is blocking the kinase domain of the PKB
T or F - PI2 paired w/ PDK2 fully activates the PKB
F - PI2, PDK1 and PDK2 are needed
Label the following
a) PDK1
b) PDK2
c) PI 3,4-bisphosphate (PI2)
d) PKB
a) pink
b) blue
c) yellow
d) green
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
- 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
- The SH2 domain of the PI3K recognizes and binds to the phosphorylated tyrosine residues on the RTK
- PI3K phosphorylates PI1 or PI2 to generate PI-3 phosphates
- the PI-3 kinases phosphorylate PI 4-phosphate to PI 3, 4-bisphosphate
- the PH domain of the PKB recognizes and binds to the membrane-bound PI 3,4-phosphate partially activating it
- the membrane-bound PDK1 and cytosolic PDK2 phosphorylate the PKB fully activating it as it activation loop has now been moved
- PKB and other kinases cause a cascade that results in cell metabolism, cell growth, and gene expression
