Lecture 7

Question 1

What is PDGF?

Answer 1

Platelet-derived growth factor.
Plays a significant role in blood vessel formation (angiogenesis), the growth of blood vessels from already-existing blood vessel tissue.

Question 2

Function of tyrosine kinase receptors

Answer 2

Tyrosine kinase receptors mediate an interacting, branching web of downstream signals, which may alter gene expression. Regulate cell growth.

Question 3

What are the four important directly recruited mediators that play plausible roles in growth regulation in response to PDGF?

Answer 3

1. Inositol Triphosphate
2. Diacylglycerols
3. GTPase-Activating Protein (GAP)
4. Tyrosine Phosphatase C

Question 4

Inositol Triphosphate

Answer 4

Mediator: Induces Ca++ release into cytoplasm, initiating downstream events

Question 5

Diacylglycerols

Answer 5

Mediator: Hydrophobic, diffuse in plane of membrane. Upon encountering protein kinase C, then phosphorylate a variety of proteins on serine or threonine residues.

Question 6

What are polypeptide growth factors?

Answer 6

Substances that stimulate an increase in cell size and/or cell number during embryonic development(embryonic???).

Question 7

How does Tyrosine Kinase Receptor Phosphorylate?

Answer 7

Homie Tyrosine Kinase Receptor crosses his arms and pulls all the phosphates (cross-phosphorylation). Leads to recruitment of downstream proteins)

Question 8

How do Polypeptide receptors work?

Answer 8

IDK, come back and answer this slide later

Question 9

Auto-cis-phosphorylation

Answer 9

Post-translational modification. Phosphorylation of the kinase by itself. When its own active site causes the phosphorylation reaction.

Question 10

Auto-trans-phosphorylation

Answer 10

Post-translational modification. Phosphorylation of the kinase by itself. When the active site of another kinase of the same type causes the phosphorylation reaction.

Question 11

SH-2 Domain

Answer 11

SH2 domains allow proteins containing those domains to dock to phosphorylated tyrosine residues on other proteins. SH2 domains are commonly found in adapter proteins that aid in the signal transduction of receptor tyrosine kinase pathways

Question 12

PDFG-receptor process –> (PI4,5)

Answer 12

PDGF-receptor recruits phospholipase-Cgamma, which cleaves PI 4,5 biphosphate, releasing inositol 1, 4, 5-trisphophate, which releases Ca++, and diacylglycerol, which (togther with phosphatidylserine) activates protein kinase C. PKC targets channels and transcription factors.

Question 13

PDFG-receptor process –> (PI3)

Answer 13

PI3 kinase, generates phosphatidyl inositols with phosphates on the 3’position (PI3; PI3,4; and PI3,4,5). PI3,4,5 will recruit BTK and phospholipase-gamma. Can also recruit and activate PDK1 and protein kinase B.

Question 14

What’s PKB?

Answer 14

Protein kinase B. Can promote cell survival by phosphorylating BAD

Question 15

What’s Phospholipase Cgamma

Answer 15

Produces diacylglycerol, which activates protein kinase C
Produces phosphatidyl (1,4,5) trisphosphate, which releases Ca++

Question 16

What’s phosphatidyl Inositol 3’ kinase

Answer 16

Produces phosphatidyl (3,4,5) trisphosphate- which recruits and activates BTK and phospholipase C to and on membrane.
Also recruits and activates PDK and protein kinase B on membrane

Question 17

What’s MAP kinase?

Answer 17

Mitogen-activated protein kinase. A important additional arm of signaling downstream of PDGF-receptor and many other growth factor receptors/tyrosine kinases

Question 18

Kinase:

Answer 18

Adds phosphate to a substrate.

ATP–> ADP

Question 19

Phosphatase:

Answer 19

Removes phosphate from a substrate.

ADP–> ATP