Chapter 14

Question 1

Signal transduction

Answer 1

the pathway that converts the information from a molecular signal to a physiological response

Question 2

Steps in a standard signal transduction pathways:

Answer 2

1. Signal release
2. A membrane-bound receptor on another cell binds the ligand and makes an intracellular conformational change
3. An intracellular secondary messenger is generated to amplify the signal
4. The cell responds to the secondary messenger by activating pumps, pathways, gene expression, etc
5. The signal must be terminated after the response

Question 3

Signal release

Answer 3

. A diffusable extracellular primary messenger or “ligand” is released.

Question 4

ligand

Answer 4

extracellular primary messenger

Question 5

Often in signal transduction there are (multiple) stages

Answer 5

amplification

Question 6

Epinephrine + B-Adrenergic receptor

Answer 6

Energy-store mobilization

Question 7

Insulin + insulin receptor

Answer 7

increased glucose uptake

Question 8

Epidermal growth factor (EGF) + EGF receptor

Answer 8

Expression of growth-promoting genes

Question 9

Examples of secondary messengers

Answer 9

cAMP, cGMP, C+, IP3, DAG

Question 10

Example of signal or primary messenger

Answer 10

epinephrine

Question 11

epinephrine

Answer 11

a hormone released by the adrenal gland in response to stress

Question 12

Does epinephrine enter the cell?

Answer 12

No, instead it “pushes the doorbell” of a specific 7TM receptor protein to effect the “fight or flight” responses (second messengers are produced inside the cell)

Question 12

largest family of receptors

Answer 12

7TM helix receptor family

Question 13

How many 7TM receptors do humans have

Answer 13

800

Question 14

7TM receptors are important for the

Answer 14

senses

Question 15

What flavors are mediated by 7TM receptors

Answer 15

sweet, bitter, and umami flavors (NOT sour or salty)

Question 16

Vision works with

Answer 16

rhodopsin, another 7TM protein

Question 17

Smell is mediated by hundreds

Answer 17

olfactory receptors, also 7TM receptors

Question 18

The 𝛽AR receptor acts as

Answer 18

GNEF

Question 19

carazolol

Answer 19

epinephrine blocker

Question 20

G-proteins

Answer 20

3 subunit complexes activated by GTP

Question 21

Cyclic amp (cAMP) exerts its effects through

Answer 21

protein kinase A (PKA)

Question 22

Phosphorylate proteins with the aa sequence

Answer 22

RRGSI

Question 23

growth-regulating kinases

Answer 23

PKA, PKB, PKC

Question 24

PKA is a four-subunit enzyme

Answer 24

2 catalytic and 2 regulatory

Question 25

Each PKA regulatory subunit functions as

Answer 25

kinase inhibitor by binding the catalytic site with a non-functional pseudosubstrate domain

Question 26

After each PKA binds 2 cAMP each

Answer 26

the R subunits dissociate from the C subunits so they are active

Question 27

Parts of the G protein

Answer 27

-α subunit -Beta subunit -GDP -fatty acid -Y subunit

Question 28

Which of the subunits, when activated, associates with adenylyl cyclase (adenylate cyclase) and enables it to assume a more catalytically active conformation

Answer 28

Gα

Question 29

Glucagon is a hormone that is released when

Answer 29

glucose in the blood is low

Question 30

Glucagon uses a G protein signaling to

Answer 30

promote glycogenolysis

Question 31

Glucagon released into the blood which will

Answer 31

1. Glucagon binds G Protein 2. G protein releases GDP and binds GTP which activates protein 3. Activated G protein activates adenylate (adenyly) cyclase 4. adenylate cyclase converts ATP to cAMP 5. Cyclic AMP activates protein kinase A (PKA) 6. kinase A phosphorylates glycogen phosphorylase 7. Glycogenolysis is promoted.

Question 32

adenylate cyclase converts ATP to

Answer 32

cAMP

Question 33

free catalytic PKA subunits interact with proteins to

Answer 33

phosphoryate Ser or THR residues

Question 34

termination of a response in the GPCR, or 7TM receptor

Answer 34

1. The G𝛼s subunit turns itself “off” by hydrolysis of GTP->GDP. This allows it to re-associate with the inhibitory 𝛽𝛾 subunits. 2. The ligand dissociates from the receptor, which resumes its inactive conformation. 3. The receptor is inactivated by phosphorylation of Ser or other residues on its intracellular domain. 4. The receptor itself is turned off by dissociation of epinephrine

Question 35

phosphorylates

Answer 35

introduce a phosphate group into (a molecule or compound).

Question 36

One of calmodulin’s main roles is to

Answer 36

to activate calmodulin-dependent protein kinases (CaM kinases).

Question 37

How is (CaM kinases) activated

Answer 37

Ca2+ induces calmodulin to bind a specific peptide on CaM kinase 1

Question 38

The binding of insulin to the insulin receptor alters

Answer 38

conformation of the two 𝛽 subunits in the cytoplasm

Question 39

tyrosine kinases

Answer 39

𝛽 subunits altered by insulin+insulin receptor

Question 40

phosphotyrosines are recongized by

Answer 40

“SH2” domain proteins

Question 41

SH2 domains are known to

Answer 41

bind phospho-tyrosine residues

Question 42

Insulin-receptor substrates (IRS) bind

Answer 42

phospho-tyrosines adjacent to phosphoinositides

Question 43

Because Akt is not achored to the membrane

Answer 43

it can diffuse to cytoplasmic targets proteins that traffic GLUT4 receptors to plasma membrane and stimulate glycogen synthesis

Question 44

RGF pathway is turned off by

Answer 44

GTP hydrolysis by Ras

Question 45

Needed to terminate EGF pathway

Answer 45

Phosphatases of the activated Raf, MEK, and ERK kinases

Question 46

Signal transduction and cancer

Answer 46

Src tyrosine kinase and Abl tyrosine kinase

Question 47

Gleevec or Imatinib

Answer 47

drug that specifically inhibits the abl tyrosine kinase by binding near the ATP binding site to competitively inhibit the kinase

Question 48

Abl tyrosine kinase causes

Answer 48

chronic myelogenous leukemia (CML)

Question 49

IP3 ->

Answer 49

Ca+

Question 50

PIP2 and PLC ->

Answer 50

DAG and IP3

Question 51

cAMP ->

Answer 51

PKA

Question 52

Ca2+

Answer 52

PKC

Question 53

ATP and adenyly cyclase

Answer 53

cAMP

Question 54

DAG ->

Answer 54

PKC

Question 55

In the context of smooth muscle contraction, which second messenger would be a direct antagonist of

Answer 55

IP3

Question 56

antibody targeting receptor

Answer 56

herceptin and erbitux