Question 1

Levels of diacylglycerol increase in a cell on binding of a ligand to a taste receptor. Which trimeric G protein subunit is most likely to be bound to GTP?

Accepted Answer

A)  Gq $\alpha$ 
B)  Gt $\alpha$ 
C)  G $\beta$ $\gamma$ 
D)  Gi $\alpha$ 
A)  Gq $\alpha$ 
B)  Gt $\alpha$ 
C)  G $\beta$ $\gamma$ 
D)  Gi $\alpha$

Question 2

A caspase is a

Accepted Answer

A)  protease. 
B)  kinase. 
C)  phosphatase. 
D)  transmembrane receptor. 
A)  protease. 
B)  kinase. 
C)  phosphatase. 
D)  transmembrane receptor.

Question 3

Which of the following is an example of a first or second messenger?

Accepted Answer

A)  peptide hormone 
B)  G protein-coupled receptor 
C)  protein kinase 
D)  cyclic nucleotide phosphodiesterase 
A)  peptide hormone 
B)  G protein-coupled receptor 
C)  protein kinase 
D)  cyclic nucleotide phosphodiesterase

Question 4

If there were a technique that allowed one to isolate EGFR1 and EGFR2 at discrete steps along their activation pathway, which of the following would be isolated?

Accepted Answer

A)  A dimer in which EGFR2 contains phosphotyrosines but EGFR1 does not. 
B)  A dimer in which EGFR1 contains phosphotyrosines but EGFR2 does not. 
C)  A monomer of EGFR1 that contains phosphotyrosines. 
D)  A monomer of EGFR2 that contains phosphotyrosines. 
A)  A dimer in which EGFR2 contains phosphotyrosines but EGFR1 does not. 
B)  A dimer in which EGFR1 contains phosphotyrosines but EGFR2 does not. 
C)  A monomer of EGFR1 that contains phosphotyrosines. 
D)  A monomer of EGFR2 that contains phosphotyrosines.

Question 5

Oncogenic Ras protein chronically stimulates the MAP kinase pathway. Why is Ras not inactivated in this situation?

Accepted Answer

Because Ra

Question 6

Glycogen metabolism is regulated when glucagon binds to $\beta$2-adrenergic receptors on liver cells. Describe the type of covalent modification that leads to this regulation and distinguish how the modification effects the rate of glycogen synthesis and glycogen degradation.

Accepted Answer

Phosphorylation activates enzy

Question 7

The ligands for metabolite receptors are often derived from dietary nutrients, including all EXCEPT which of the following?

Accepted Answer

A)  essential amino acids 
B)  vitamins 
C)  unsaturated fatty acids 
D)  saturated fatty acids 
A)  essential amino acids 
B)  vitamins 
C)  unsaturated fatty acids 
D)  saturated fatty acids

Question 8

Which of the following is true of active NF$\kappa$B?

Accepted Answer

A)  It is a dimer. 
B)  It is phosphorylated. 
C)  It is in a complex with a DD. 
D)  It has been proteolytically activated. 
A)  It is a dimer. 
B)  It is phosphorylated. 
C)  It is in a complex with a DD. 
D)  It has been proteolytically activated.

Question 9

What characteristic is true for both RTKs and GPCRs?

Accepted Answer

A)  The receptor binds to intracellular proteins only when activated. 
B)  When activated, the receptor has enzymatic activity. 
C)  The receptor transmits ions. 
D)  The receptor undergoes a conformational change on activation. 
A)  The receptor binds to intracellular proteins only when activated. 
B)  When activated, the receptor has enzymatic activity. 
C)  The receptor transmits ions. 
D)  The receptor undergoes a conformational change on activation.

Question 10

Differentiate between the caspase in the apoptotic pathway that is activated by autocleavage and the caspase that is activated by another enzyme. Clearly name each caspase.

Accepted Answer

Caspase 8 is activat

Question 11

This Zn2+-containing homodimer is part of

Accepted Answer

A)  the glucocorticoid receptor. 
B)  PPAR$\gamma$-RXR$\alpha$. 
C)  TRADD. 
D)  the retinoic acid receptor. 
A)  the glucocorticoid receptor. 
B)  PPAR$\gamma$-RXR$\alpha$. 
C)  TRADD. 
D)  the retinoic acid receptor.

Question 12

On binding of an insulin molecule to the insulin receptor, a conformational change occurs that

Accepted Answer

A)  increases the affinity of a second insulin binding site. 
B)  causes the dimerization of the receptor. 
C)  brings the L1 region of the $\beta$ subunit closer to the membrane. 
D)  stimulates tyrosine autophosphorylation in the $\beta$ subunits. 
A)  increases the affinity of a second insulin binding site. 
B)  causes the dimerization of the receptor. 
C)  brings the L1 region of the $\beta$ subunit closer to the membrane. 
D)  stimulates tyrosine autophosphorylation in the $\beta$ subunits.

Question 13

A culture of insulin-responsive cells are analyzed after stimulation with insulin. The insulin receptors are then isolated (assume that during the isolation protocol the insulin is removed from the receptor). Half of the sample is analyzed by SDS-PAGE followed by Coomassie blue staining. The other half of the sample is analyzed via SDS-PAGE followed by a Western blot. The primary antibody used in the blot recognizes phosphorylated tyrosine residues. Predict how many bands will be seen on the SDS-PAGE compared with the Western blot and explain your answer.

Accepted Answer

There will be two bands on the SDS-PAGE,

Question 14

The __________ domain functions as a protein-protein interaction module and is located in the cytoplasmic tail of TNF receptors.

Accepted Answer

A)  death 
B)  SH2 
C)  SH3 
D)  RIP 
A)  death 
B)  SH2 
C)  SH3 
D)  RIP

Question 15

Construct a functional pathway out of the following steps. A: Phosphorylation of $\beta$ subunits of the insulin receptor occurs. B: Insulin binds to $\alpha$ subunits of the insulin receptor.
C: PI-3K is activated.
D: IRS is phosphorylated.

Accepted Answer

A)  C, A, B, D 
B)  B, D, A, C 
C)  B, A, C, D 
D)  B, A, D, C 
A)  C, A, B, D 
B)  B, D, A, C 
C)  B, A, C, D 
D)  B, A, D, C

Question 16

Construct the order of signaling termination through the $\beta$-adrenergic receptor that includes the following steps:
A. Internalization of the receptor into endosomes
B. Dissociation of heterotrimeric G protein complex from the receptor
C. Phosphorylation of the receptor
D. Recruitment of $\beta$ARK to the receptor
E. $\beta$-arrestin association with GPCR

Accepted Answer

The answer of Construct the order of signaling termination through...

Question 17

Which of the following DNA sequences is MOST likely to be bound by a steroid receptor?

Accepted Answer

A)  AGGAGAACATCATGTTCT 
B)  AGGAGATAGGAGAACT 
C)  TTTGATCCAGTTTCCAGT 
D)  CCCAAGTTCCCAAG 
A)  AGGAGAACATCATGTTCT 
B)  AGGAGATAGGAGAACT 
C)  TTTGATCCAGTTTCCAGT 
D)  CCCAAGTTCCCAAG

Question 18

The $\alpha$ subunit of trimeric G proteins can function to

Accepted Answer

A)  regulate ion channels. 
B)  activate adenylate cyclase. 
C)  inhibit phospholipase A. 
D)  inhibit phosphodiesterase. 
A)  regulate ion channels. 
B)  activate adenylate cyclase. 
C)  inhibit phospholipase A. 
D)  inhibit phosphodiesterase.

Question 19

Both the silence of death domain and TNF receptor-associated death domain proteins

Accepted Answer

A)  inhibit downstream signaling. 
B)  activate downstream signaling. 
C)  are phosphorylated when TNF-$\alpha$ is bound to its receptor. 
D)  bind TNF receptor death domains. 
A)  inhibit downstream signaling. 
B)  activate downstream signaling. 
C)  are phosphorylated when TNF-$\alpha$ is bound to its receptor. 
D)  bind TNF receptor death domains.

Question 20

Below is a schematic representation of a dimerized receptor tyrosine kinase. Where is the kinase function located?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
A)  A 
B)  B 
C)  C 
D)  D

Exam 8: Cell Signaling Systems

Levels of diacylglycerol increase in a cell on binding of a ligand to a taste receptor. Which trimeric G protein subunit is most likely to be bound to GTP?

A caspase is a

Which of the following is an example of a first or second messenger?

If there were a technique that allowed one to isolate EGFR1 and EGFR2 at discrete steps along their activation pathway, which of the following would be isolated?

Oncogenic Ras protein chronically stimulates the MAP kinase pathway. Why is Ras not inactivated in this situation?

Glycogen metabolism is regulated when glucagon binds to β\betaβ 2-adrenergic receptors on liver cells. Describe the type of covalent modification that leads to this regulation and distinguish how the modification effects the rate of glycogen synthesis and glycogen degradation.

The ligands for metabolite receptors are often derived from dietary nutrients, including all EXCEPT which of the following?

Which of the following is true of active NF κ\kappaκ B?

What characteristic is true for both RTKs and GPCRs?

Differentiate between the caspase in the apoptotic pathway that is activated by autocleavage and the caspase that is activated by another enzyme. Clearly name each caspase.

This Zn2+-containing homodimer is part of

On binding of an insulin molecule to the insulin receptor, a conformational change occurs that

The __________ domain functions as a protein-protein interaction module and is located in the cytoplasmic tail of TNF receptors.

Construct a functional pathway out of the following steps. A: Phosphorylation of β\betaβ subunits of the insulin receptor occurs. B: Insulin binds to α\alphaα subunits of the insulin receptor. C: PI-3K is activated. D: IRS is phosphorylated.

Which of the following DNA sequences is MOST likely to be bound by a steroid receptor?

The α\alphaα subunit of trimeric G proteins can function to

Both the silence of death domain and TNF receptor-associated death domain proteins

Below is a schematic representation of a dimerized receptor tyrosine kinase. Where is the kinase function located?

Principles of Biochemistry

Physical Biochemistry: Energy Conversion, Water, and Membranes

Nucleic Acid Structure and Function

Protein Structure

Methods in Protein Biochemistry

Protein Function

Enzyme Mechanisms

Glycolysis: a Paradigm of Metabolic Regulation

The Citrate Cycle

Oxidative Phosphorylation

Photosynthesis

Carbohydrate Structure and Function

Carbohydrate Metabolism

Lipid Structure and Function

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Metabolic Integration

DNA Replication, Repair, and Recombination

RNA Synthesis, Processing, and Gene Silencing

Protein Synthesis, Posttranslational Modification, and Transport

Gene Regulation

Filters

Glycogen metabolism is regulated when glucagon binds to $\beta$ 2-adrenergic receptors on liver cells. Describe the type of covalent modification that leads to this regulation and distinguish how the modification effects the rate of glycogen synthesis and glycogen degradation.

Which of the following is true of active NF $\kappa$ B?

This Zn²⁺-containing homodimer is part of

Construct a functional pathway out of the following steps. A: Phosphorylation of $\beta$ subunits of the insulin receptor occurs. B: Insulin binds to $\alpha$ subunits of the insulin receptor. C: PI-3K is activated. D: IRS is phosphorylated.

The $\alpha$ subunit of trimeric G proteins can function to