Lecture 12- Introduction to Signaling

Question 1

In terms of speed of intracellular responses, how do they occur?

Answer 1

They can occur slowly or rapidly.

Question 2

What does signaling require and what carries out signaling?

Answer 2

Signaling requires catalysis and is carried out by enzymes.

Question 3

What removes terminal phosphates added by kinases, thereby reversing their effects?

Answer 3

Phosphatases.

Question 4

What would be a rapid intracellular response to a signal?

Answer 4

A signal that alters the function of a protein, like an ion channel.

Question 5

What would be a slow intracellular response to a signal?

Answer 5

A signal that causes changes in gene expression.

Question 6

Signaling events utilize what 2 molecular switches?

Answer 6

Kinases and GTPases.

Question 7

What transfers the terminal phosphate of ATP to other proteins in a process called phosphorylation?

Answer 7

Protein kinases.

Question 8

What are kinases and GTPAses examples of?

Answer 8

They are examples of molecular switches for signaling events.

Question 9

What are protein kinases?

Answer 9

They are enzymes that transfer the terminal phosphate of ATP to other proteins in a process called phosphorylation.

Question 10

When GTPases are bound to GTP, are they on or off?

Answer 10

On.

Question 11

What are the two classes of kinases?

Answer 11

Serine/Theronine kinase and Tyrosine kinase.

Question 12

How are kinases and phosphatases regulated?

Answer 12

By other kinases or phosphatases.

Question 13

What do GTPases do?

Answer 13

They are molecular switches that bind and hydrolyze GTP.

Question 14

What binds and hydrolysis GTP?

Answer 14

GTPases.

Question 15

When GTPases hydrolyze their bound GTP, are they on or off.

Answer 15

Off.

Question 16

When are GTPases in the “ON/Active” state? When are they in the “OFF/Inactive” state?

Answer 16

When GTPases are bound to GTP; When GTPases hydrolyzes their bound GTP.

Question 17

What do phoshphatases do?

Answer 17

Phosphatases remove the terminal phosphate added by kinases, thereby reversing their effects.

Question 18

What is a generic signaling pathway?

Answer 18

Extracellular signaling molecule->receptor protein->intracellular receptor protein->effector protein.

Question 19

What receives extra cellular signals?

Answer 19

A receptor protein.

Question 19

What is the basic structure of a G-protein linked receptor?

Answer 19

A single polypeptide chain that crosses the plasma barrier 7 times.

Question 20

What controls specificity of intracellular signaling cascades and insures that intracellular cascade signals are related efficiently?

Answer 20

Scaffold proteins.

Question 21

What are the two kinds of GTPases?

Answer 21

Trimeric GTPases and small GTPases.

Question 22

What relays signals from cell surface receptors?

Answer 22

Intracellular signaling cascades.

Question 23

What are trimeric GTPases?

Answer 23

They are found in a complex with two other proteins and relay signals from G protein-linked receptors.

Question 24

Which of the two kinds of GTPases act as monomers and relay intracellular signals?

Answer 24

Small GTPases.

Question 25

What are examples of modular boning domains?

Answer 25

SH2 (Src homology domain 2), PTB (phosphotyrosine binding), which both bind to phosphorylated tyrosines, SH3 (Src homology domain 3), which binds to short proline sequences, and PH (Pleckstrin homology), which bind to phosphoinositides.

Question 25

What are G-protein-linked receptors?

Answer 25

Large family of receptor proteins that mediate many different signaling events.

Question 26

Which kind of GTPase is found in complex with two other proteins and relays signals from G protein-linked receptors?

Answer 26

Trimeric GTPases.

Question 27

What has the basic structure of a single polypeptide chain the crosses the plasma membrane 7 times?

Answer 27

G-protein-linked receptors.

Question 29

Signaling complexes are often assembled by what?

Answer 29

Modular binding domains.

Question 33

What do intracellular signaling complexes do?

Answer 33

They enhance the speed, efficiency, and specificity of signaling.

Question 35

What do scaffold proteins do?

Answer 35

They bring together specific protein kinases to relay the signal effectively. They also control specificity by ensuring that kinases only signal to proteins bound to the scaffold.

Question 36

How do scaffolds control specificity?

Answer 36

They ensure that kinases only signal to proteins bound to the scaffold.

Question 37

Conceptually, what do intracellular signaling cascades do?

Answer 37

They relay signals from cell surface receptors.

Question 38

What is the term for "a large family of receptor proteins that mediate many different signaling events."

Answer 38

G-protein-linked receptors.

Question 39

SH2 and PTB, SH3, and PH are examples of what?

Answer 39

Signaling complexes.

Question 40

What are often assembled by modular binding domains?

Answer 40

Signaling complexes.

Question 41

What do Small GTPases do?

Answer 41

They act as monomers and relay intracellular signals.

Question 42

How are GTPases regulated?

Answer 42

By GAPs and GEFs.