Chapter 16

1.

1 point

Serum response factor (SRF) is phosphorylated by

p90^RSK.

Raf.

MAP kinase.

MEK.

Ras.

2.

1 point

Scaffold proteins that bind multiple enzymes of a particular signaling pathway are important in cellular signaling because they:

prevent cross-talk between different signaling pathways

allow for cross-talk between different signaling pathways

sequester enzymes away from their substrates

prevent enzymes from entering the nucleus

3.

1 point

Gleevec is a new generation drug for targeted therapy. Its effectiveness lies in its

inhibition of Bcr-abl fusion kinase

activation of Bcr-abl fusion kinase.

4.

1 point

MAP kinase kinase (MEK) is called a “dual specificity kinase” because:

it can phosphorylate serine and threonine residues

it can phosphorylate and dephosphorylate at tyrosine residues

it can phosphorylate tyrosine, serine and threonine residues

it can phosphorylate and dephosphorylate at serine and threonine residues

5.

1 point

Starting from a ligand that is going to bind its receptor, the temporal order of events most likely will be:

2-1-3-4-5

2-1-4-3-5

2-4-3-5-1

2-4-3-1-5

2-4-5-3-1

6.

1 point

In puzzle piece 3, what might A? and B? stand for?

A?---RafK, B?---MEK

A?---TCF, B?--- c-Fos protein

A?---MEK, B?---MAPK

A?---RTK, B?---MAPK

7.

1 point

Which of the following functions as an allosteric molecule?

a) cAMP (in the regulation of PKA)

b) O2 in the regulation of hemoglobin

c) Ca2+ in the regulation of calmodulin

d) a and c

e) a, b, and c

8.

1 point

A phosphatase catalyzes:

the addition of a phosphate to a protein

all these answers are stoopid

the removal of a phosphate from of a protein or lipid

the removal of ubiquitin from a protein

the addition of an amino acid to a polypeptide chain

9.

1 point

Which of the following events occurs first as a result of EGF binding to its receptor?

Activation of a GTPase

Activation of a phospholipase

Activation of a serine/threonine kinase

Activation of a tyrosine kinase

Activation of a tyrosine phophatase

10.

1 point

Which is NOT true for c-fos gene ?

It encodes a transcription factor

It is important for cells going through the restriction point.

It is a delayed response gene

It is an early response gene

11.

1 point

Binding of hormone to a receptor tyrosine kinase causes all of the following except

dimerization of the receptor.

autophosphorylation of the receptor.

activation of Ras through an interaction with GRB2 and Sos.

hydrolysis of GTP bound to Ras.

12.

1 point

Which domain(s) preferentially binds to phosphotyrosine residues?

a. SH3 domain

b. SH2 domain

c. PTB domain

d. PH domain

e. b and c

13.

1 point

The SH3 domain in the GRB2 protein

a) binds to phosphorylated tyrosine

b) binds to proline-rich sequence

c) binds to 3,4,5-phosphatidylinositol

d) a and b

14.

1 point

Dimerization of receptors occurs because of what changes on the RTK molecules?

ligand induced conformational changes

phosphorylation at other residues in the cytoplasmic domain

phosphorylation at activation lip

interaction with the SH2 domain of GRB2

15.

1 point

Ras is a(n)

all these answers are wrong

guanine nucleotide exchange factor.

kinase.

protease.

adapter protein.

16.

1 point

Ras is anchored at the membrane through

interacting with GDP or GTP

a covalently linked lipid molecule (prenylation)

a transmembrane domain

interaction with microfilaments

17.

1 point

The EGF receptor is a(n)

kinase

guanine nucleotide exchange protein

protease

adapter protein

biology term

18.

1 point

Which of the following are enzyme pairs that catalyze opposite reactions?

NF-kB and I-kB

all wrong

MEK and MAP kinase

JAK kinases and STATs

PI-3 kinase and PTEN phosphatase

19.

1 point

Mutations on ras oncogenes have been found in 50% of tumors. The mutations usually lock Ras protein in an active state. This means

Ras exhibits increased GEF activity.

Ras exists preferentially in a GDP bound form.

Ras exhibits increased GTPase activity.

Ras exists preferentially in a GTP bound form

20.

1 point

Negative feedback of signal transduction can be achieved through the following EXCEPT

Opening calcium channels on the ER membrane

Phosphorylating the receptor to downregulate its activity

endocytosis of membrane bound receptors

Removal of the extracellular signal

21.

1 point

Which is most likely NOT a reason that anti-Her2 antibody help controlling cancer growth?

Her2 expression in cancer cells is usually lower than normal cells.

Her2 forms heterodimers with other EGF receptors.

Her2 has an intrinsic tyrosine kinase activity.

22.

1 point

By what mechanism does PI-3 phosphate promote activation of protein kinase B (PKB)?

a. recruiting PKB to the plasma membrane

b. recruiting the activating kinase PDK1 to the plasma membrane

c. releasing inhibition of the catalytic site by the PH domain

d. a and b

e. all of the above

23.

1 point

Phosphorylation of transcription factor TCF is carried out by

activated MEK

activated MAPK

activated RTK

activated Raf

24.

1 point

A phosphatase catalyzes:

the addition of a phosphate to a protein

the addition of an amino acid to a polypeptide chain

the removal of a phosphate from of a protein or lipid

all these answers are stupid

the removal of ubiquitin from a protein

25.

1 point

The tyrosine kinase activity of the receptors are activated through

Phosphorylation by Raf

each receptor in the dimerized form phosphorylates a tyrosine residue at the activation lip of the other receptor.

Interaction with the SH2 domain of GRB2

each receptor in the dimerized form phosphorylates a tyrosine residue at its own activation lip

26.

1 point

PH domain binds to

phosphotyrosine

is proline rich

binds inositol-3-phosphate

27.

1 point

There are two major types of proteins kinases that phosphorylate on different residues. The residues are

a. Serine/Threonine

b. tyrosine

c. cysteine

d. a and c.

e. a and b.

28.

1 point

When the NF-kB signaling pathway is activated, which will NOT happen?

I-kBa will be phosphorylated

I-kBa will be ubiquitinylated and degraded

NF-kB will be ubiquitinylated

NF-kB will be translocated into nuclei

29.

1 point

Which of the following is a GEF?

Sos

Ras bound with GTP

Ras bound with GDP

GRB2