Chapter 10

Question 1

Caffeine is antagonist for ____ receptor

Answer 1

adenosine

Question 2

Bacterial Quorum Sensing

Answer 2

Sense # organisms in population.

Diffuse through cell membrane, bind to intracellular receptors, effect change in gene receptors

Question 3

What do kinases do?

Answer 3

Gene expression and metabolic activity

Question 4

limits of signaling (6)

Answer 4

1. amplified intracellularly (stepwise)
2. regulation
3. location: cytosol/nuclear
4. branching: redundancy/cancellation
5. signal termination (2nd messengers short lived)
6. desensitization

Question 5

PKA

Answer 5

Ser/Thr kinase

Activation up when phosphorylated (phospho-Thr)
When activated,
Phospho-Thr —-> Arg (+, arginine)

Asp (-, asparagine) near 3rd phosphate and substrate

Question 6

What 2 things activate PKA?

Answer 6

Allosteric activation by cAMP

Priming phospho-thr

Question 7

Insulin effects

Answer 7

increases glycogen synthesis
decreases phosphorylation

opposite PKA, PKA gives fuel mobilization signal

Question 8

Arrestin

Answer 8

Docking protein. When GPCR bound, kinase phosphorylates it. Arrestin recognizes phosphorylated form of G protein.

G protein docking and thus the signal

Arrestin removed by dephosphorylated.

Question 9

Where is PIP2 cleaved?

Answer 9

C3

Question 10

What does IP3 activate?

Answer 10

Calcium released –> PKB/Akt

Question 11

What does DAG activate?

Answer 11

PKC

Question 12

What 2 things activate PKC?

Answer 12

Requires priming at Thr?

DAG causes dock near membrane and conformation change

Question 13

Calmodulin

Answer 13

Regulates calcium
Activates or inhibits target proteins

Bends in 1/2 to grasp target

Binds 2x calcium ions

Question 14

Cross-Talk between signaling pathways (due to intracellular components) name examples

Answer 14

PLC activated by PTKs lipid phosphatases

Sphingomyelinases release sphingosine & ceramide (activate 2nd messengers)

Ceramide = 2nd messenger

Sphingosine-1-phosphate= intra/extracellular signal (-PLC, +GPCRs, aker export by ABC transport) must be exported by ABC but then can diffuse to modify GPCRs

Question 15

Ras Pathway

Answer 15

1. RTK+ Ras* GDP inactive
2. Ligand binds, RTK phosphorylates
3. Adaptor proteins connect Ras to RTK/phosphates
4. Induced Ras to release GDP and bind to GTP
5. Activates Kinase

Question 16

What does Ras target?

Answer 16

Nuclear proteins, which alter gene expression= transcription factors

Question 17

What limits Ras signaling

Answer 17

GTPase activity

Question 18

What reverses kinase effects ?

Answer 18

phosphatases

Question 19

Anticancer drugs

Answer 19

inhibit kinases, stop uninhibited growth

Question 20

In lipid hormone signaling, ___ binds to DNA and initiates transcription.

Answer 20

Hormone responsive element (HRE)

Question 21

What eicosanoid signaling molecule enzyme converts arachnodonate to prostaglandin H2.

Answer 21

Cyclooxygenase

Question 22

Eicosanoids produced when ________activated by phosphorylation and by presence of Ca2+.

Answer 22

phospholipase A2

Question 23

Why is ligand binding reversible

Answer 23

non-covalent

Question 24

Kinase

Answer 24

enzyme that transfers a phosphoryl group from ATP to another molecule.

Question 25

GPCR structure

Answer 25

7 transmembrane alpha helices Pal @ cys Ligand binding: helical core and extracellular loops

Question 26

Beta blockers

Answer 26

Block beta2-Aderngic | Treat high bp

Question 27

how does intrinsic GTPase activity limit a G protein?

Answer 27

Bound GTP --- > GDP

Question 28

____ is allosteric activator of kinase

Answer 28

cAMP

Question 29

When threonine on PKA not phosphorylated,

Answer 29

active site blocked

Question 30

Arrestin has ___ residues which bind to phosphoryl group.

Answer 30

Lys (+) and Arg (arginine, +) Arrestin uses endocytosis

Question 31

What changes loop blocking PKC active site?

Answer 31

noncovalent binding with DAG

Question 32

Phosphoinositide signaling pathway regulation:

Answer 32

1. Lipid phosphatases: remove phosphoryl groups from PIP2 | 2. Sphingosine inhibits PLC (see above)

Question 33

What stops Ras signaling?

Answer 33

Proteins that enhance GTPase activity so it returns to inactive GDP bound form Phosphatases reverse some kinases. Tyrosine kinases can cross-talk (see book for additional notes)

Question 34

Lipids carried in bloodstream by specific carrier protein or ___, all purpose binding protein.

Answer 34

albumin

Question 35

Lipid Receptor

Answer 35

2 zinc fingers: cross links formed by 4 cysteine residues interacting with 4 zinc ions.

Question 36

Once lipid ligand binds, moves to ____ and binds to HRE, which all have ____

Answer 36

nucleus 6-bp sequences separated by a few bp

Question 37

Are lipid signals long lasting?

Answer 37

no short range, degraded quickly because unstable and hydrophobic