Cell Signaling 3

Question 1

What are Regulators of G-protein Signaling (RGS) proteins?

Answer 1

A family of proteins that accelerate the intrinsic GTPase activity of the G alpha subunit

Question 2

How do RGS proteins help terminate GCPR activation??

Answer 2

By binding to the G alpha subunit and promoting GTP hydrolysis

Question 3

What does GAP stand for?

Answer 3

GTPase Activating Protein

Question 4

What family of enzymes shut OFF cAMP/cGMP signaling?

Answer 4

Phosphodiesterases

Question 5

What reaction do Phosphodiesterases catalyze?

Answer 5

They turn cAMP/cGMP to non cyclic 5’ AMP or 5’ GMP

Question 6

Which PDE is specific for cAMP?

Answer 6

PDE4

Question 7

Which PDE is specific for cGMP?

Answer 7

PDE5

Question 8

Which PDE can interact with cAMP or cGMP?

Answer 8

PDE1

Question 9

What does SGP stand for?

Answer 9

Small G Proteins

Question 10

What is an SGP like structurally?

Answer 10

Monomeric

Question 11

What is the function of SGPs?

Answer 11

They are downstrean cogs in the GPCR signaling cascade that help control a multitude of cellular functions

Question 12

Do SGPs bind to GTP or GDP?

Answer 12

Both

Question 13

When are SGPs active?

Answer 13

When they are bound to GTP

Question 14

What “-ase” ability do SGPs have?

Answer 14

GTPase

Question 15

What signal activates SGP activity?

Answer 15

GTP exchange factors (GEF)

Question 16

What signal terminates SGP activity?

Answer 16

GTPase Activating Factors (GAP)

Question 17

What 3 amino acids are phosphorylated as part of the cell metabolism regulation?

Answer 17

Serine
Threonine
Tyrosine

Question 18

What regulatory proteins oppose Phosphorylation?

Answer 18

Protein Kinases

Phophotases

Question 19

What enzymes help to phosphorylate the amino acids?

Answer 19

Kinases

Question 20

What enzyme helps remove the phosphate?

Answer 20

Phosphotases

Question 21

What are the two major classes of Protein Kinases?

Answer 21

Serine/Threonine

Tyrosine

Question 22

What are the 5 Serine/Threonine Protein Kinases?

Answer 22

cAMP Dependent (PKA)
cGMP Dependent (PKG)
Protein Kinase C (PKC)
Ca2+/Calmodulin Dependent (CaMK)
MAP Kinase (MAPK)

Question 23

What does it mean if PKA is in its basal state?

Answer 23

Low cAMP concentration

Inactive

Question 24

In its basal state, what is the structure of PKA?

Answer 24

Tetramer
2 Regulator (R) Subunits
2 Catalytic (C) Subunits

Question 25

What is a holoenzyme?

Answer 25

An activated enzyme that is the combo of an enzyme with a co-enzyme

Question 26

How many cAMP molecules can bind to PKA?

Answer 26

4, two per (R) subunit

Question 27

When cAMP levels rise to a high enough concentration what happens?

Answer 27

When cAMP binds to the R subunits the PKA molecule dissociates into the dimeric R subunits and 2 C subunits

Question 28

How is PKA dissociation regulated?

Answer 28

When cAMP levels drop then the R and C subunits re-associate

Question 29

How is PKC activated?

Answer 29

Receptor mediated hydrolysis of DAG and IP3

Question 30

What is a MAPK?

Answer 30

A MAP Kinases (mitogen-activated) are kinases that can carry a message into the nucleus and effect transcription

Question 31

What is the order of the MAPK cascade

Answer 31

MAPKKK MAPKK MAPK

Question 32

Phosphotases turn "OFF" the protein phosphorylation switch. What are the two broad classes of Phosphotases?

Answer 32

Serine/Threonine | Tyrosine

Question 33

What are the 2 hallmarks of cell signaling?

Answer 33

Specificity | Amplification

Question 34

What is another name for Receptor Tyrosine Kinases (RTK)

Answer 34

Growth Factor Receptor

Question 35

What is the general physical structure of all RTKs?

Answer 35

Extracellular binding domain Hydrophobic transmembrane domain Intracellular tyrosine kinase domain

Question 36

What is the only RTK that isn't monomeric

Answer 36

Insulin receptors

Question 37

What are the examples given for RTK functions?

Answer 37

Cell proliferation | Cell differentiation

Question 38

What kind of conformational change occurs upon ligand binding for RTKs?

Answer 38

Dimerization

Question 39

What happens on the Tyrosine domain upon ligand binding?

Answer 39

Tyrosine phosphorylation via Intrinsic Tyrosine kinases

Question 40

What does the phosphorylation of the Tyrosine lead to?

Answer 40

Recruitment of signaling molecules via the opening of new binding sites

Question 41

What molecules are attracted to the new binding sites?

Answer 41

Grb2 which contains SH2 | Grb2-associated Sos protein

Question 42

What is Sos protein?

Answer 42

A guanosine exchange factor (GEF) | and an activator of Small G Protein RAS

Question 43

Draw out the RTK Cascade

Answer 43

Ok

Question 44

What types of reactions does the Insulin Receptor manage?

Answer 44

Glucose and energy metabolism

Question 45

What is the structure of the insulin receptor?

Answer 45

Disulfide linked dimer Two polypeptide chains Alpha/Beta Heterodimer

Question 46

What signaling pathway does the Insulin Receptor rely on?

Answer 46

PI3K

Question 47

Draw the Insulin Receptor Cascade

Answer 47

Ok