Final

Question 1

How is Trimeric G protein signaling analogous to Electronic commjunication?

Answer 1

Extracellular signaling molecules are like the signal, The receptor proteins act as the antenna picking up the signal, The intracellular signaling proteins activated by the receptor act as modulators and amplifiers of the signal. Target proteins within the cell that are activated by the itnracellular signaling proteins act a s post amplifiers. The music that is a result of the all the previous steps is analogous to the effects the signal pathway has on the cell weather it be changes in cell metabolism, altered gene expression, or altered cell shape or movement.

Question 2

Pleckstrin Homology Domain

Answer 2

binds phosphatidylinositol lipids within biological membranes and proteins such as the βγ-subunits of heterotrimeric G proteins, and protein kinase C

Question 3

Scatchard

Answer 3

a plot of the ratio of concentrations of bound ligand to unbound ligand versus the bound ligand concentration. It is a method for analyzing data for freely reversible ligand/receptor binding interactions

Question 4

Dynamin

Answer 4

a GTPase responsible for endocytosis in the eukaryotic cell

Question 5

GEF

Answer 5

Guanine nucleotide exchange factor, proteins or protein domains that activate monomeric GTPases by stimulating the release of guanosine diphosphate (GDP) to allow binding of guanosine triphosphate (GTP)

Question 6

PTB

Answer 6

Phosphotyrosine-binding domains, protein domains which bind to phosphotyrosine

Question 7

SH2 Domain

Answer 7

binds phosphorylated tyrosines

Question 8

Enzyme linked receptors

Answer 8

Respond to extracellular signals by promoting growth, proliferation, and survival of cells

Question 9

What are the six classes of enzyme linked receptors?

Answer 9

Receptor tyrosine kinases, Tyrosine kinase-associated receptors, receptor-like tyrosine phosphatases, receptor serin/theronine kniases, Receptor guanylyl cyclases, Histidine kinase-associated receptors.

Question 10

What happens when the ligand binds to receptor tyrosine kinases?

Answer 10

activates an intracellular tyrosine kinase domain

Question 11

Ephrins

Answer 11

largest class of membrane-bound ligands and regulate cell adhesion and repulsion, can initiate bidirectional signaling between cells

Question 12

What is the receptor for the Ephrin ligand?

Answer 12

Eph receptor

Question 13

What is a result of phosphorylation of tyrosines within the kinase domain?

Answer 13

increase kinase activity of the receptor

Question 14

What happens to tyrosines outside of the kinase domain?

Answer 14

create high affinity binding sites for intracellular signaling molecules

Question 15

What do phosphorylated tyrosines serve as?

Answer 15

docking sites for proteins with SH2 domains

Question 16

Ras

Answer 16

a monomeric GTPase, is connected to the plasma membrane by a farnesyl lipid anchor, switches on other proteins, which ultimately turn on genes involved in cell growth, differentiation and survival

Question 17

Agonist

Answer 17

mimic the function of a hormone by binding a receptor and causing a normal response

Question 18

Antagonists

Answer 18

bind to the receptor but do not induce a normal physiological response

Question 19

What are the 5 ways target cells are desensitized?

Answer 19

Receptor sequestration, Receptor down-regulation, Receptor inactivation, Inactivation of signaling protein, Production of Inhibitory protein

Question 20

What are the 3 subunits of G proteins?

Answer 20

Alpha, beta, and gamma

Question 21

What happens if no ligand is bound to the receptor?

Answer 21

GDP is bound to the complex

Question 22

What happens when the ligand binds to the receptor?

Answer 22

GDP is exchanged for GTP then G-alpha-GTP complex separates and the complex interacts with an effector

Question 23

What causes the G-alpha-GTP complex to dissociate from the target protein?

Answer 23

Hydrolysis of GTP to GDP

Question 24

What happens to the inactive G-alpha-GDP complex?

Answer 24

Reassembles with beta-gamma-subunit to reform an inactive G protein complex

Question 25

GAP

Answer 25

GTPase activating proteins, type of adaptor protein that enhances GTPase activity of the G-alpha-GTP complex

Question 26

RGS

Answer 26

Regulator of G protein signaling, type of Adaptor protein that regulates G protein signaling

Question 27

Target proteins

Answer 27

proteins that are bound to by G-alpha-GTP complex to produce small intracellular mediators called “second messengers”

Question 28

What are three example of small intracellular mediators (second messegers)

Answer 28

cAMP, Ca2+, DAG

Question 29

Integrator Proteins

Answer 29

integrate signals from two or more signaling pathways and

Question 30

Kd

Answer 30

concentration of ligand at which the receptor is half saturated

Question 31

What target protein produces cyclic AMP when activated?

Answer 31

Adenylyl cyclase

Question 32

What effect does cAMP have on the PKA pathway?

Answer 32

cAMP activates PKA which enter the nucleus and activates CREB which binds with CBP(creb binding protein) and binds to the CREB binding element activating the target gene and producing a new protein

Question 33

What activates Phospholipase C?

Answer 33

seven-spanning receptors and G proteins

Question 34

DAG

Answer 34

diacyglycerol, activates a Ca2+ dependent protein kinase C

Question 35

What effect does activating Phospholipase C have?

Answer 35

Activates IP3 which signals release of Ca2+ from the ER

Question 36

Calmadulin

Answer 36

Binds Ca+2 and mediates its effects

Question 37

What happens when Ca2+ levels rise?

Answer 37

cause PKC to bind to the plasma membrane where it can be activated by DAG