QUESTION 1 You are working with a mutant cell which contains a G?i protein that

Question

QUESTION 1

You are working with a mutant cell which contains a G?i protein that can not hydrolyze GTP to GDP. What would you expect concerning the state of downstream signaling molecules in this mutant cell?

PKA would be highly activated in these cells

CREB would be phosphorylated at a high level in these cells

cAMP levels would be very low in these cells

Both a an b

All of the above

QUESTION 2

Which of the following are NOT TRUE about tyrosine kinase associated receptors?

they have tyrosine kinase domains

the alpha interferon receptor is an example of a tyrosine kinase associated receptor

they bind to tyrosine kinases

ligand binding results in phosphorylation of the cytoplasmic tails of the receptors on tyrosines

QUESTION 3

PI3 Kinase can be activated by Ras, GPCRs and RTKs. Select the best function of PI3 kinase from the choices below:

Phosphorylates inositol phospholipids on the plasma membrane to create binding sites for other signaling molecules

Phosphorylates inositol phospholipids on cell surfacereceptors creating binding sites for other signaling molecules

Phosphorylates receptor cytoplasmic tails allowing for recruitment of MAP kinases resulting in gene expression

Phosphorylates receptor cytoplasmic tails allowing for recruitment of Ras, resulting in activation of multiple signaling pathways

QUESTION 4

You have been studying the effects of vitamin D on gene expression. What kind of receptor do you expect to be involved in this response?

GPCR

enzyme linked receptor

ion channel

Nuclear receptor

QUESTION 5

If phosphorylation of an intracellular signaling molecule promotes signaling, then which enzyme would you expect to turn off signaling?

phosphatase

kinase

GTPase

phospholipase

QUESTION 6

You are studying the localization of a steroid hormone receptor in cells using fluorescent microscopy. You have tagged the receptor with GFP (green fluorescent protein) and are looking to see where the receptor goes under different conditions. You treat the cells with the cortisol. Where do you expect to find the green fluorescence?

cytoplasm

cell surface

nucleus

ER

QUESTION 7

Ras is a GTP binding protein that acts to relay signals from a receptor to different pathways. It is always bound to the plasma membrane. How is it activated?

Ligand binding results in phosphorylation of a GEF

Ligand binding results in phosphorylation of the receptor and recruitment of a GAP

Ligand binding results in phosphorylation of the receptor and recruitment of a GEF

Ligand binding results in phosphorylation of Ras

PKA would be highly activated in these cells

CREB would be phosphorylated at a high level in these cells

cAMP levels would be very low in these cells

Both a an b

All of the above

Explanation / Answer

1. D. Both A and B

2. A

3. A

4. D Nuclear receptors

5. A phosphatase

6. C nucleus

7. C

Related Questions

Navigate

• Browse (All)
• Browse Q
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.