Chapter 13 Signal-Transduction Pathways

Front 1

information embodied in the interaction between a ligand and its receptor molecule

Back 1

primary messenger

Front 2

small molecule that binds to a protein, inducing a specific structural change

Back 2

ligand

Front 3

What is a ligand for a steroid-hormone receptor?

Back 3

steroid

Front 4

small signal molecule whose concentration changes in response to a primary messenger

Back 4

second messenger

Front 5

belongs to a class of integral membrane proteins in which the intramembrane part consists of helical regions

Back 5

seven-transmembrane-helix (7TM) receptor

Front 6

What are 7TM receptors always coupled to?

Back 6

G proteins

Front 7

guanyl nucleotide-binding protein that is a component of intracellular signaling pathways

Back 7

G protein

Front 8

What is the G protein sometimes called?

Back 8

heterotrimeric G protein

Front 9

What does the G protein consist of in the inactive state?

Back 9

alpha-Beta-gamma subunits, with the GDP bound to the alpha subunit

Front 10

What does the G protein consist of in the active state?

Back 10

GTP bound to the alpha subunit

Front 11

When is signal propagation of G protein terminated?

Back 11

when the alpha subunit hydrolyzes GTP to GDP and reassociates with the Beta-gamma subunits

Front 12

guanyl nucleotide-binding subunit of heterotrimeric G proteins

Back 12

Galpha

Front 13

dimeric component of G proteins

Back 13

G(Beta-gamma)

Front 14

What helps to maintain the Galpha component in the inactive state?

Back 14

G(Beta-gamma)

Front 15

True or false: in some signal-transduction pathways, the G(Beta-gamma) component can also function as a second messenger.

Back 15

true

Front 16

What are G-protein-coupled receptors?

Back 16

7TM receptors

Front 17

What is GPCR?

Back 17

G-protein-coupled receptor

Front 18

What enzyme generates cyclic adenosine monophosphate from ATP?

Back 18

adenylate cyclase

Front 19

True or false: cyclic adenosine monophosphate is a primary messenger.

Back 19

false, second

Front 20

What is PKA?

Back 20

protein kinase A

Front 21

What does protein kinase consist of?

Back 21

two catalytic subunits and two regulatory subunits that inhibit the catalytic subunits

Front 22

What happens to PKA on binding of cyclic AMP?

Back 22

regulatory subunits dissociate from the catalytic subunits, which then become active

Front 23

set of reactions that convert an extracellular signal into an intracellular one

Back 23

phosphoinositide cascade

Front 24

What does the conversion in a phosphoinositide cascade entail?

Back 24

cleavage of the phospholipid phosphatidylinositol 4,5-bisphosphate into two second messengers: inositol 1,4,5-triphosphate and diacylglycerol

Front 25

enzyme that catalyzes the degradation of phospholipids in signal-transduction pathways

Back 25

phospholipase C

Front 26

What two second messengers does phospholipase C catalyze the formation of?

Back 26

inositol 1,4,5-trisphosphate, a soluble molecule that can diffuse from the membrane

diacylglycerol, which stays in the membrane

Front 27

protein kinase that is activated by the binding of diacylglycerol

Back 27

protein kinase C (PKC)

Front 28

transmembrane receptor protein that, when bound to the appropriate signal molecule, displays intracellular protein kinase activity, phosphorylating proteins at tyrosine residues

Back 28

receptor tyrosine kinase (RTK)

Front 29

What is RTK?

Back 29

receptor tyrosine kinase

Front 30

List the means by which the Beta-adrenergic pathway is terminated.

Back 30

Dissociation of epinephrine from the receptor. Conversion of cAMP into AMP by phosphodiesterase and the subsequent inhibition of PKA. Conversion of GTP into GDP by Galpha and the subsequent reformation of the inactive heterotrimeric G protein.

Front 31

Why does it make good physiological sense for insulin to increase the number of glucose transporters in the cell membrane?

Back 31

Insulin signifies the fed state. Its presence leads to the removal of glucose from the blood for storage or metabolism. Increasing the number of glucose transporters available makes these biochemical processes more efficient.

Front 32

What is heterotrimeric G-protein activated by?

Back 32

7TM receptor

Front 33

What is stimulated by cAMP?

Back 33

protein kinase A

Front 34

What results in the reassociation of Galpha and G(Beta-gamma)?

Back 34

GTPase activity

Front 35

What generates two second messengers?

Back 35

phospholipase C

Front 36

What is activated by diacylglycerol?

Back 36

protein kinase C

Front 37

What is GPCR composed of?

Back 37

seven-transmembrane helices (7TM)

Front 38

message received by the cell

Back 38

primary messenger

Front 39

What results from Galphai inhibition?

Back 39

pertussis

Front 40

What activates phospholipase C?

Back 40

Galphaq

Front 41

What activates adenylate cyclase?

Back 41

Galphas

Front 42

What activates a Ca2+ channel?

Back 42

inositol triphosphate

Front 43

What is due to persistent stimulation of Galphas?

Back 43

cholera

Front 44

intracellular chemical that relays message from ligand receptor complex

Back 44

second messenger

Front 45

What results in the inactivation of PKA?

Back 45

cAMP phosphodiesterase

Front 46

What are the three major classes of membrane receptors?

Back 46

G-protein coupled (7TM) receptors

receptors that dimerize on ligand binding and recruit tyrosine kinases

receptors that dimerize on ligand binding that are tyrosine kinases (RTK)