Akt promotes the survival of many cells by affecting the activity of Bad and Bcl2, as diagrammed in Figure Q16-58. Which of the following statements is false?

Akt promotes the survival of many cells by affecting the activity of Bad and Bcl2, as diagrammed in Figure Q16-58. Which of the following statements is false?

(a) In the presence of a survival signal, Akt is phosphorylated.
(b) In the absence of a survival signal, Bad inhibits the cell-death inhibitor protein Bcl2.
(c) In the presence of a survival signal, the cell-death inhibitory protein Bcl2 is active.
(d) In the absence of a survival signal, Bad is phosphorylated.


Answer: D

The activation of the serine/threonine protein kinase Akt requires phosphoinositide 3-kinase (PI 3-kinase) to _________.

The activation of the serine/threonine protein kinase Akt requires phosphoinositide 3-kinase (PI 3-kinase) to _________.

(a) activate the RTK.
(b) create phosphorylated lipids that serve as docking sites that localize Akt to the plasma membrane.
(c) directly phosphorylate Akt.
(d) to create DAG.


Answer: 

Which of the following statements is true?

Which of the following statements is true?

(a) MAP kinase is important for phosphorylating MAP kinase kinase.
(b) PI 3-kinase phosphorylates a lipid in the plasma membrane.
(c) Ras becomes activated when an RTK phosphorylates its bound GDP to create GTP.
(d) STAT proteins phosphorylate JAK proteins, which then enter the nucleus and activate gene transcription.

Answer: 

Male cockroaches with mutations that strongly decrease the function of an RTK called RTKX are oblivious to the charms of their female comrades. This particular RTK binds to a small molecule secreted by sexually mature females. Most males carrying loss-of-function mutations in the gene for Ras protein are also unable to respond to females. You have just read a paper in which the authors describe how they have screened cockroaches that are mutant in RTKX for additional mutations that partly restore the ability of males to respond to females. These mutations decrease the function of a protein that the authors call Z. Which of the following types of protein could Z be? Explain your answer.

Male cockroaches with mutations that strongly decrease the function of an RTK called RTKX are oblivious to the charms of their female comrades. This particular RTK binds to a small molecule secreted by sexually mature females. Most males carrying loss-of-function mutations in the gene for Ras protein are also unable to respond to females. You have just read a paper in which the authors describe how they have screened cockroaches that are mutant in RTKX for additional mutations that partly restore the ability of males to respond to females. These mutations decrease the function of a protein that the authors call Z. Which of the following types of protein could Z be? Explain your answer.

(a) a protein that activates the Ras protein by causing Ras to exchange GDP for GTP
(b) a protein that stimulates hydrolysis of GTP by the Ras protein
(c) an adaptor protein that mediates the binding of the RTKX to the Ras protein
(d) a transcriptional regulator required for the expression of the Ras gene

Answer: 

You are interested in further understanding the signal transduction pathway that controls the production of Pig1, a protein important for regulating cell size. Activation of the TRK receptor leads to activation of the GTP-binding protein, Ras, which then activates a protein kinase that phosphorylates the SZE transcription factor. SZE only interacts with the nuclear transport receptor when it is phosphorylated. SZE is a gene activator for the Pig1 gene. This pathway is diagrammed in Figure Q16-50.Normal cells grown under standard conditions (without ligand) are 14 µm in diameter while normal cells exposed to TRK ligand are 10.5 µm in diameter. Given this situation, which of the following conditions do you predict will more likely lead to smaller cells?

You are interested in further understanding the signal transduction pathway that controls the production of Pig1, a protein important for regulating cell size. Activation of the TRK receptor leads to activation of the GTP-binding protein, Ras, which then activates a protein kinase that phosphorylates the SZE transcription factor. SZE only interacts with the nuclear transport receptor when it is phosphorylated. SZE is a gene activator for the Pig1 gene. This pathway is diagrammed in Figure Q16-50.Normal cells grown under standard conditions (without ligand) are 14 µm in diameter while normal cells exposed to TRK ligand are 10.5 µm in diameter. Given this situation, which of the following conditions do you predict will more likely lead to smaller cells?

(a) addition of TRK ligand and a drug that stimulates the GTPase activity of Ras
(b) addition of TRK ligand and a drug that inhibits the activity of the phosphatase that acts on SZE
(c) addition of TRK ligand and a drug that stimulates the degradation of Pig1
(d) addition of TRK ligand and a drug that inhibits Pig1 binding to DNA

Answer: 

Which of the following mechanisms is not directly involved in inactivating an activated RTK?

Which of the following mechanisms is not directly involved in inactivating an activated RTK?

(a) dephosphorylation by serine/threonine phosphatases
(b) dephosphorylation by protein tyrosine phosphatases
(c) removal of the RTK from the plasma membrane by endocytosis
(d) digestion of the RTK in lysosomes

Answer: 

A protein kinase can act as an integrating device in signaling if it ___________________.

A protein kinase can act as an integrating device in signaling if it ___________________.

(a) phosphorylates more than one substrate.
(b) catalyzes its own phosphorylation.
(c) is activated by two or more proteins in different signaling pathways.
(d) initiates a phosphorylation cascade involving two or more protein kinases.

Answer: