Chapter 15 Part 2

Question 1

What is an enzyme coupled receptor?

Answer 1

they are transmembrane proteins that bind to ligands that have cytosolic domains that rather contain its own kinase activity OR associates with a kinase

Question 2

What is a receptor tyrosine kinase (RTK)?

Answer 2

it is a transmembrane receptor that contains a cytosolic domain with instrinic kinase activity

Question 3

what is a non receptor kinase?

Answer 3

its a transmembrane receptor that associated with a activate enzymes for its kinase albility

Question 4

what are the 4 characteristics of a Receptor Tyrosine Kinase?

Answer 4

• large cytosolic domain for kinase and phosphorylate
• extracelluar domain for ligand binding
• single transmembrane helix that participates in dimerization
• dimerization activates the RTK

Question 5

What are the 3 ways to promote dimerization?

Answer 5

1) a dimer ligand it associates with 2 monomer receptors
2) a monomer ligand interacts with 2 monomer receptors
3) two monomeric ligands can independently bind to 2 monomeric receptors

all ways results in trans-autophosphoylation between the 2 identical monomers

Question 6

What does dimerization allow?

Answer 6

Activation and the phosphorylated tyrosines will now act like doing sites for SH2, SH3 and PTB

Question 7

What are the compositions of SRC homology (SH2 or SH3) ?

Answer 7

it is an effector protein composed of about 100 amino acids and contains a binding pocket for the phosphorites tyrosine residue

Question 8

What are PTB domains?

Answer 8

they are phosphotryosine binding domains that can bind to phosphorylated tyrosine residues usually present as Asn-Pro-X-Tyr

Question 9

What is the roles of SH2 and PTB domains (4)

Answer 9

• adapter proteins that become a binding sit for all other molecules
• docking proteins supplying receptors with tyrosine phosphorylation site
• signalling enzymes (kinases)
• transcription factors

Question 10

How does the response end?

Answer 10

• internalization of the receptor through clathrin mediated endocytosis
• degraded in lysosomes
• return to the plasma membrane

Question 11

What type of tyrosine kinase is SRC?

Answer 11

it a non receptor tyrosine kinase

Question 12

What are the steps of the RAS-Map pathway?

Answer 12

1) ligand binds to RTK activating it
2) The adaptor protein (Grb 2 that contains SH2 and SH3) interacts with SOS (a Ras-GEF) to activate Ras Protein
3) Ras Protein interacts with Raf to activate it
4) Raf phosphorylates Mek
5) Mek phosphorylates Erk
6) Erk phosphorylates proteins that changes activity and regulatory genes that changes expression

Question 13

What is Raf?

Answer 13

MAP kinase kinase kinase

Question 14

what is Mek?

Answer 14

MAP kinase kinase

Question 15

what is Erk?

Answer 15

MAP kinase

Question 16

what is the role of Rho?

Answer 16

regulate actin microtubules for controlling sharp and motility

Question 17

What prevents Rho from binding to the membrane when it is inactive?

Answer 17

GDI- guanine nucleotide dissociation inhibitor

Question 18

What is the oncogene?

Answer 18

a normal gene that has mutated into a gain of function gene

Question 19

What is the proto oncogene?

Answer 19

a normal gene that has the possibility of turning into a proto oncogene

Question 20

what is the onco-protein?

Answer 20

the type of protein a oncogene makes

Question 21

What is the proto oncoprotein?

Answer 21

the type of protein a proto oncogene makes

Question 22

what is the gain of function mutation?

Answer 22

the cell is always on and can not be downregulated meaning it will keep reproducing

Question 23

c-src is a example of what?

Answer 23

proto oncogene

Question 24

v src is an example of what?

Answer 24

oncogene