section 7 - cell signaling

Question 1

receptor tyrosine kinases (rtk)

Answer 1

• proteins that can bind to a ligand
• an amino acid that can be phosphorylated
• a protein that can add a phosphate to another protein

Question 2

ligand mediated dimerization

Answer 2

(bivalent ligand)
- single ligand binds two receptors at same time
- receptors come together to form an active dimer

Question 3

receptor mediated dimerization

Answer 3

(monovalent ligand)
- two ligands bind to different receptors
- receptors come together to form an active dimer

Question 4

ligand-mediated and receptor-mediated, once dimerized go through the —- mechanism

Answer 4

the same mechanism

Question 5

trans-autophosphorylation

Answer 5

kinase activity of one receptor phosphorylates tyrosine residues in the other dimer, and vice versa

Question 6

signal transmisson

Answer 6

now dimer is a recruiting station, other proteins come to it
- SH2 domain and PTB domain

Question 7

proteins with — or — domains will bind to rtks

Answer 7

SH2 or PTB domains
SH2 = Src Homology 2
PTB = Phospho Tyrosine-Binding

Question 8

Four classes of proteins have these domains and interact with RTKS

Question 9

adaptor proteins

Answer 9

will focus on Ras-MAP pathway
- act like a link between proteins

Question 10

2. Ras-MAP kinase pathway (ex. of RTK pathway)

Answer 10

Ras -> small, monomeric G proteins (only a single small protein)
- anchored at inner surface of plasma membrane by lipid group

Question 11

the Ras-MAP pathway

Answer 11

1. RTKs get activated
2. Grb2 recruits Sos (adaptor)
3. Sos (GEF for Ras) changes to GTP
4. Ras-GTP
5. activate membrane-bound Raf
6. Raf leaves the membrane and phosphorylates MEK
7. MEK phosphorylates ERK
8. ERK turns on transcription factors in the nucleus, which turns on genes involved in cell proliferation
9. MKP-1 dephosphorylates ERK to stop further signaling (sends negative feedback)

Question 12

Mitogen

Answer 12

any protein that activates mitosis is a mitogen

Question 13

MAP =

Answer 13

mitogen activated pathway

Question 14

all members of this pathway can ——— when mutated

Answer 14

cause cancer because of not being sensitivity to “on/off” signaling

Question 15

proto-oncogenes

Answer 15

genes that have the potential to push the cell towards the malignant state
- can be converted to oncogenes

Question 16

oncogene

Answer 16

gene that encodes for a protein that promotes loss of growth control

Question 17

signaling pathways are often

Answer 17

interconnected
- signals come in from three different receptors all converge on Ras