Deck 14: Signal-Transduction Pathways

Question 1

What family of proteins contains the Ras proteins?

A) GAP proteins
B) G-protein receptor kinases
C) small G proteins
D) seven-transmembrane helix receptors
E) heterotrimeric G proteins

Answer 1

C

Question 2

_______________________ binds to the extracellular side of β-adrenergic receptors.

Answer 2

Epinephrine

Question 3

The cytosolic side, or β subunit, of the insulin receptor is a ________________ kinase.

Answer 3

tyrosine

Question 4

Important second messengers include cAMP, cGMP, calcium ion, _______________________, and diacylglycerol.

Question 5

Input from several signaling pathways is called _____________________.

Question 6

The catalytically active form of the insulin receptor is a result of phosphorylation of specific ____________ residues in the activation loop.

Question 7

EGF signaling is terminated by the action of phosphatases and the hydrolysis of bound _____________ by Ras.

Question 8

What is covalently attached to the $\alpha$ and $\gamma$ subunits of heterotrimeric G proteins in order to anchor the protein to the cell membrane?

A) galactose
B) N-acetylgalactosamine
C) cholesterol
D) phosphatidyl serine
E) fatty acid

Question 9

What is a gene that leads to the transformation of susceptible cell types into cell types with cancer-like characteristics?

A) protogene
B) retrogene
C) epigene
D) oncogene
E) None of the answers is correct.

Question 10

Which of the following is the inactive form of protein kinase A?

A) R₂C₂
B) R₄C₂
C) R₂C₄
D) R₄C₄
E) None of the answers is correct.

Question 11

The binding of IP₃ to the IP₃ receptor results in the release of __________ from the endoplasmic reticulum.

Question 12

What enzyme catalyzes the cleavage of PIP₂?

A) phospholipase A
B) phospholipase C
C) phospholipase D
D) phospholipase P
E) None of the answers is correct.

Question 13

Which of the following is another name for a seven-transmembrane helix receptor?

A) tyrosine kinase receptor
B) ion channel receptor
C) enzyme-linked receptor
D) β-adrenergic receptor
E) None of the answers is correct.

Question 14

The ________ receptor is approximately 50% identical in amino acid sequence with the EGF receptor and has similar domain structure, but it does not bind any known ligand.

Question 15

Protein kinase A phosphorylates serine and ___________ residues.

Question 16

What enzyme becomes active when bound to Ca²⁺ and diacylglycerol?

A) calmodulin
B) protein kinase A
C) protein kinase C
D) phospholipase C
E) adenylate cyclase

Question 17

____________ is the membrane protein that catalyzes the conversion of ATP to cAMP.

Question 18

What eukaryotic protein serves as an intracellular Ca²⁺ sensor by binding to four calcium ions?

A) calmodulin
B) phospholipase C
C) protein kinase C
D) vitamin D-dependent calcium binding protein
E) calcitonin

Question 19

What is the primary messenger that is released by the adrenal gland?

A) dopamine
B) epinephrine
C) glucagon
D) insulin
E) acetylcholine

Question 20

What is a gene that contributes to cancer development only when deleted or damaged?

A) oncogene
B) proto-oncogene
C) viral oncogene
D) carcinoma-suppressor gene
E) tumor-suppressor gene

Question 21

Why is bound GTP considered a "clock"?

A) It is always produced and degraded in specific time intervals.
B) It is regulated by energy.
C) The G _$\alpha$ receptors have intrinsic GTPase activity, hydrolyzing GTP to GDP and P_i.
D) It spontaneously hydrolyzes in the binding site of G proteins.
E) None of the answers is correct.

Question 22

Common elements that occur in many signal transduction pathways include which of the following?

A) Specialized domains mediate specific interactions in the pathway.
B) Second messengers may participate.
C) Cell division is usually the result.
D) A and B
E) All of the answers are correct.

Question 23

What are some of the common structural features of the receptors to which signal molecules bind?

Question 24

Which of the following is a common example of a mechanism by which a signaling process might be terminated?

A) change in temperature
B) aggregation of all protein subunits
C) protein dephosphorylation by phosphatases
D) All of the answers are correct.
E) None of the answers is correct.

Question 25

What happens when signaling paths are not terminated properly?

Question 26

What is the general mechanism for signal transmission by 7TM receptors?

Question 27

Which of the following is an example of a disease that is caused by altered G-protein activity?

A) whooping cough
B) cholera
C) bubonic plague
D) whooping cough and cholera
E) whooping cough and bubonic plague

Question 28

Which form of the guanyl nucleotide is bound to a G protein in its unactivated state?

A) GTP
B) GDP
C) GMP
D) dGTP
E) None of the answers is correct.

Question 29

How does the binding of epinephrine to its receptor set a response in action?

A) It causes an exchange of GTP for G protein bound GDP.
B) It causes a pore to open, allowing proton/ion exchange.
C) It causes the release of insulin.
D) It causes G proteins to produce cGMP.
E) None of the answers is correct.

Question 30

______________ may be effective anti-cancer drugs.

A) Monoclonal antibodies against offending receptors
B) EGF mimics
C) Protein kinase inhibitors
D) All of the answers are correct.
E) Both monoclonal antibodies against offending receptors and protein kinase inhibitors

Question 31

The enzyme responsible for induction of the phosphoinositide cascade is

A) phospholipase C.
B) phospholipase A.
C) C-dependent protein (CDP).
D) calmodulin.
E) None of the answers is correct.

Question 32

Most signal molecules

A) easily diffuse through the membrane and bind to a receptor in the cytoplasm.
B) bind to membrane receptors and transmit information across a membrane without traversing the membrane.
C) carry out functions in the nucleus after binding to a receptor in the cell membrane.
D) easily diffuse through the membrane and bind to a receptor in the nucleus.
E) None of the answers is correct.

Question 33

Examples of second messengers include

A) cAMP.
B) calcium.
C) inositol 1,4,5-trisphosphate.
D) cGMP.
E) All of the answers are correct.

Question 34

Advantages of second messengers include

A) the signal can be amplified by making many second messengers.
B) second messengers can freely diffuse to other sites within the cell.
C) a few common second messengers can be used in multiple signaling pathways.
D) All of the answers are correct.
E) A and C.

Question 35

How is calmodulin activated?

A) by binding both calcium and potassium
B) by binding Ca²⁺ when the cytosolic concentration is greater than 500 nM
C) by binding to a positively charged helix on another protein
D) by binding Ca²⁺ only when calcium channels are open, allowing Ca²⁺ efflux from the cell
E) None of the answers is correct.

Question 36

Which of the following amino acids can be phosphorylated?

A) Tyr, Ser, Thr
B) Tyr, Ser, Trp
C) Ser, Thr, Asn
D) His, Ser, Phe
E) Tyr, Met, Trp

Question 37

How many 7TM membranes exist? What are some of their functions?

Question 38

The v and c in v-src and c-src refer to

A) viral and cellular.
B) viral and cytosolic.
C) viral and cystic.
D) Vibrio and cholera.
E) None of the answers is correct.

Question 39

What is a disadvantage of using common molecules for signaling paths?

Question 40

Cross-phosphorylation of the EGF receptor is possible when two receptor proteins

A) are cleaved.
B) dimerize.
C) are internalized into organelles.
D) covalently cross link.
E) None of the answers is correct.

Question 41

What is the relationship between monoclonal antibodies, breast cancer, and HER2?

Question 42

What are receptor tyrosine kinases? Provide an example.

Question 43

How is the hormone-bound activated receptor reset after activation?

Question 44

What is the difference between heterotrimeric G proteins and small G proteins?

Question 45

What is the difference between an oncogene and a proto-oncogene?

Question 46

Draw the reaction catalyzed by tyrosine kinase (no mechanism necessary).

Question 47

In addition to its range in concentration, what other property of calcium ion makes it a highly suitable messenger?

Question 48

What is meant by an EF hand? Draw or describe the structure.

Question 49

Describe two roles of phosphatidylinositol 4,5-bisphosphate (PIP₂) in signal transduction.