Lecture On Chapter 13

Front 1

Signal released in response to a physiological stimulus like low blood glucose.

Back 1

primary message

Front 2

Where does a ligand fit into the signal transduction pathway?

Back 2

primary message or signal

Front 3

What is an example of a ligand?

Back 3

insulin

Front 4

What does primary signal bind to?

Back 4

receptor

Front 5

What kind of protein is a receptor usually?

Back 5

integral membrane protein

Front 6

How is the primary message/signal transduced to the cell interior?

Back 6

generation of an intracellular second message

Front 7

What does the activation of effector molecules by the second messenger produce?

Back 7

physiological responses

Front 8

What is the signal transduction pathway referred to as?

Back 8

signal cascade

Front 9

What are the five steps in the signal transduction pathway?

Back 9

signal

reception

transduction

response

termination

Front 10

When does amplification of the signal transduction pathway occur?

Back 10

between reception and transduction

Front 11

How is input signal amplified?

Back 11

copy is made, increasing output

Front 12

intracellular molecules that change in concentration in response to environmental signals

Back 12

second messengers

Front 13

What conveys information inside the cell?

Back 13

change in concentration of second messengers

Front 14

What are four examples of second messengers?

Back 14

cAMP/cGMP

Ca2+ ion (surrounded by water)

Inositol 1,4,5-triphosophate (IP3)

Diacylglycerol (DAG)

Front 15

What are the three major classes of membrane receptors?

Back 15

seven transmembrane receptors

dimeric membrane receptors that recruit protein kinases

dimeric protein receptors that are protein kinases

Front 16

What are associated with heterotrimeric G-proteins?

Back 16

seven transmembrane receptors

Front 17

receptors that mediate a host of biological functions by responding to a variety of signal molecules

Back 17

seven-transmembrane-helix (7TM)

Front 18

What signal molecules do 7TM respond to?

Back 18

ligands

Front 19

What are three examples of ligands that 7TMs respond to?

Back 19

hormones

tastants

photons

Front 20

What does the binding of a ligand outside the cell induce?

Back 20

structural change in the receptor that can be detected inside the cell

Front 21

What type of receptor is the Beta-adrenergic receptor?

Back 21

7TM

Front 22

How is the Beta-adrenergic receptor activated?

Back 22

by binding to epinephrine, also called adrenaline

Front 23

What happens to the Beta-adrenergic receptor upon binding of epinephrine?

Back 23

Its cytoplasmic aspect activates a heterotrimeric G-protein.

Front 24

Describe the G-protein cycle.

Back 24

Hormone binds to receptor, causing GDP to come off and GTP to come on. GTP is the activated version of the G-protein. GTP then undergoes hydrolysis and turns back off, returning to GDP and allowing the cycle to restart.

Front 25

heterotrimer consisting of an alpha subunit, bound to G_P, and beta and gamma subunits

Back 25

inactive G-protein

Front 26

How do G-proteins become active?

Back 26

ligand binds to 7TM receptor, causing GDP to be replaced by GTP

Front 27

How are G-proteins inactivated?

Back 27

slowly by their own GTPase activity

Front 28

What does hydrolysis of GTP do? (2)

Back 28

deactivates the G-protein

permits assembly of the inactive G-alpha-beta-gamma complex

Front 29

What receptor is responsible for the activation of G-protein?

Back 29

Beta-adrenergic

Front 30

What integral membrane enzyme does the G protein stimulate?

Back 30

adenylate cyclase

Front 31

What does the activation of adenylate cyclase lead to?

Back 31

synthesis of the second message, cyclic adenosine monophosphate (3'5'-cAMP)

Front 32

What does cyclic AMP activate?

Back 32

protein kinase A

Front 33

What does protein kinase A do?

Back 33

targets proteins that regulate cellular processes

Front 34

How can the epinephrine-initiated pathway be shut down?

Back 34

activated G-protein's inherent GTPase activity

Front 35

What does GTPase do?

Back 35

cleaves GTP to GDP

Front 36

True or false: the alpha subunit bound to GDP spontaneously resassociates with the Beta and gamma subunits, terminating the activity of the G protein.

Back 36

true

Front 37

Describe the adenylyl cyclase signaling pathway. (5)

Back 37

Hormones activate the trimeric G-protein Ga.

A subunit of the G-protein stimulates adenylyl cyclase to produce cAMP.

cAMP is a second messenger.

cAMP activitates protein kinase A (PKA)

PKA phosphorylates cellular enzymes and other protein to affect metabolic pathways and other cellular processes.

Front 38

What does vasopressin do?

Back 38

regulates water retention

Front 39

What activate a small part of the phosphoinositide pathway?

Back 39

Some hormones, such as vasopressin, that couple to G-proteins.

Front 40

What activates the enzyme phospholipase C?

Back 40

GTP-bound G-protein

Front 41

What does phospholipase C cleave?

Back 41

membrane lipid phosphatidylinositol bisphosphate (PIP2)

Front 42

What two second messengers does phospholipase C cleave PIP2 into?

Back 42

inositol 1,4,5-triphosphate (IP3)

diacylglyceral (DAG)

Front 43

What is IP3?

Back 43

inositol 1,4,5-triphosphate

Front 44

What is DAG?

Back 44

diacylglycerol

Front 45

What is PLC?

Back 45

phospholipase C

Front 46

What does phospholipase C cleave the bond between?

Back 46

DAG and original phosphate group

Front 47

What does IP3 bind to?

Back 47

IP3-gated channel (receptor) in the ER

Front 48

What does IP3 binding cause?

Back 48

influx of Ca2+ ions into the cytoplasm

Front 49

What is a function of Ca2+ in conjunction with DAG?

Back 49

activation of protein kinase C

Front 50

What is PIP2?

Back 50

phosphatidylinositol 4,5-bisphosphate

Front 51

Where is PIP2 found?

Back 51

inner leaflet of the plasma membrane

Front 52

How are IP3 and DAG generated?

Back 52

receptor-stimulated hydrolysis PIP2 by phospholipase C

Front 53

What are IP3 and DAG?

Back 53

second messengers

Front 54

activates calcium release from the ER

Back 54

IP3

Front 55

activates protein kinases like protein kinase C

Back 55

DAG

Front 56

What are two examples of growth factor?

Back 56

insulin and growth hormone

Front 57

What does growth factor binding promote?

Back 57

receptor dimerization

Front 58

What are many receptors that dimerize able to phosphorylate?

Back 58

tyrosine

Front 59

What is TK?

Back 59

receptor tyrosine kinase

Front 60

What is TK and what three things does it contain?

Back 60

multifunctional transmembrane protein

receptor

membrane-spanning segment

effector domain containing tyrosine kinase activity

Front 61

What is the transducer of TK?

Back 61

membrane-spanning segment

Front 62

What does the binding of a ligand to the extracellular domain of the receptor tyrosine kinase activate?

Back 62

tyrosine kinase activity, which phosphorylates the dimer partner and also phosphorylates substrate proteins

Front 63

Where does tyrosine kinase activity occur?

Back 63

on the inner leaflet of the plasma membrane

Front 64

What does the activated insulin-receptor kinase initiate?

Back 64

kinase cascade

Front 65

What occurs upon insulin binding?

Back 65

tyrosine kinase activation

Front 66

What occurs after tyrosine kinase is activated?

Back 66

phosphorylation of insulin-receptor substrates

Front 67

What is IRS?

Back 67

insulin receptor substrate

Front 68

What happens after IRSs are phosphorylated?

Back 68

They transmit insulin signal to phosphoionositide-3 kinase.

Front 69

What is PI 3-kinase?

Back 69

phosphoinositide-3 kinase, a lipid kinase

Front 70

What does PI 3-kinase do?

Back 70

phosphorylates PIP2 to form PIP3

Front 71

What binds to PIP3 and becomes activated?

Back 71

PDK1 protein kinase

Front 72

What does active PDK1 do?

Back 72

phosphorylates substrates like the Akt protein kinase

Front 73

What is PDK1?

Back 73

PIP3-dependent kinase

Front 74

What does PDK1 activate?

Back 74

kinase AKT

Front 75

phosphorylates proteins to promote delivery of secretory vesicles containing GLUT4 to the plasma membrane

Back 75

AKP

Front 76

What is GLUT4?

Back 76

glucose transporter

Front 77

What does GLUT4 moving to the plasma membrane do?

Back 77

increases glucose uptake by cells

Front 78

What controls the breakdown of glycogen to glucose?

Back 78

AKT

Front 79

What is the end result of insulin signaling?

Back 79

increased glucose transporter (GLUT4) on cell surface

Front 80

What substrate was used as a substrate for two signaling pathways?

Back 80

PIP2

Front 81

What two signaling pathways is PIP2 involved in and what does it activate?

Back 81

insulin signaling and activation of Akt-type protein kinases

calcium signaling and activation of protein kinase C

Front 82

How is the signal usually terminated in pathways containing a G-protein?

Back 82

GTP is hydrolyzed by the GTPase activity of the G-protein.