Receptors

Question 1

What is the structure of GPCR

Answer 1

7 transmembrane helices (integral membrane protein)

Question 2

GPCR extracellular side

Answer 2

Ligand binding

Question 3

GPCR intracellular side

Answer 3

G protein binding —> induces conformational chance

Question 4

Ligand binding signal active

Answer 4

GDP attached to alpha subunit unit; Ligand binds making 1 helice move inducing conformational change releasing GDP and binding GTP.

Question 5

Ligand binding signal inactive

Answer 5

G alpha connected to GTP dissociated from Gby subunits; then G alpha hydrolyzes GTP to GDP + pi to turn inactive

Question 6

What GPCR is Epi an agonist for

Answer 6

Beta 2 adrenergic receptor

Question 7

What does G alpha attached to GTP have high affinity for?

Answer 7

Adenyly Cyclase which will signal to make CAMP to produce fight or flight response

Question 8

1st messenger

Answer 8

Ligand (ex epi)

Question 9

2nd messenger

Answer 9

Relay signal from membrane to target protein inside cell (ex CAMP targeting PKA)

Question 10

Protein Kinase A

Answer 10

2 regulatory subunits, each with 2 camp binding sites (and alanine)

Question 11

What happens after camp binds to the regulatory sub unit

Answer 11

The catalytic subunit will transfer a phosphate from ATP to a serine or threonine side chain on target proteins

Question 12

What is the conformational change of PKA caused by camp?

Answer 12

2 camps disconnect catalytic subunits from regulatory subunits that then move on to Phosphorylated

Question 13

Amplification

Answer 13

Each active enzyme can activate multiple downstream components ; nonlinear pathways; multiple steps allow levels of regulation (glucagon released for low blood glucose)

Question 14

How is the GPCR pathway turned of

Answer 14

Reversing or blocking events that were turned on; GTP to GDP and Pi to stop AC from making camp

Question 15

Phosphotases

Answer 15

Remove phosphate groups through hydrolysis; reverse proteins that added phosphate groups to target proteins (kinases)

Question 16

Phosphodiesterase

Answer 16

Hydorlyze camp so pka regulatory subunits reassociate with catalytic subunits to turn pka off

Question 17

Arrestin

Answer 17

Binds to GPCR to terminate G protein signaling by binding to GPCR

Question 18

Stimulatory G protein

Answer 18

AC is continually active leading to increased cellular camp concentrations

Question 19

Inhibitory G protein

Answer 19

AC is continually inhibited leasing to decrease in cellular camp concentrations

Question 20

Kinases

Answer 20

Transfer a phosphate group between nucleotides and target proteins

Question 21

Kinases

Answer 21

Transfer a phosphate group between nucleotides and target proteins

Question 22

RTK ligand binding signal activation

Answer 22

Binding to extracellular domain of RTK dimer caused conformational change in cyctolic domains where one monomer mover close to the other to Phosphorylated Try resides

Question 23

RTK activation induces what

Answer 23

A kinase cascade to amplify the signal

Question 24

Role of Tyr in RTK

Answer 24

Tyr has hydroxyl group that acts as a nucleophile for phosphorylation

Question 25

Adapter proteins

Answer 25

Require phosphate group to be active; contain phosphotyrosine binding domains

Question 26

RAS

Answer 26

Monomeric G protein (homologous to g alpha) that is activated by an adapter protein that recognizes phosphoTyr on the RTK with growth factor ligand bound to it

Question 27

How does RAS activate

Answer 27

Exchanges GDP for GTP ; initiates kinase cascade that regulates genes and cell division

Question 28

RAS steps

Answer 28

Autophosphorylation occurs, adapter proteins are recruited, RAS exchanges GDP for GTP to activate kinase cascade

Question 29

Lipid hormones relationship with receptors

Answer 29

Lipid hormones move into the cell to activate intracellular receptors causing a conformational change (dimerization) so dimer can act as a transcription factor

Question 30

Retinoate

Answer 30

Vitamin A derivative; once protonated can move across membrane

Question 31

Thyroxine (t3) and thriodothronine (t4)

Answer 31

Regulate metabolism

Question 32

Cortisol

Answer 32

Only hormone able to cross membranes directly; receptor found in the cell (cholesterol —> cortisol)

Question 33

Hormone

Answer 33

Long signaling molecule released by one tissue to target a distant tissue

Question 34

Local mediator

Answer 34

Released by one tissue to affect neighboring cells with the same tissue (short lived)

Question 35

Arachidonate

Answer 35

20 carbon FA, cleaved from membrane phospholipids by phospholipases (can be blocked by cortisol-like steroids)

Question 36

Cycloxygenase enzymes

Answer 36

Cox enzymes convert arachidonat to prostaglandin that promote pain and inflammation response

Question 37

Cox 1

Answer 37

Protect stomach lining, support kidney function, maintain clotting

Question 38

Cox 2

Answer 38

Pain, inflammation, kidney function

Question 39

Cox 2

Answer 39

Pain, inflammation, kidney function

Question 40

What do aspirin and advil inhibit

Answer 40

Both Cox 1(bad) and Cox2 (good)

Question 41

Celebrex

Answer 41

Inhibits only cox 2 but not cox1 due to steric clash

Question 42

GDP-alpha

Answer 42

Inactive ; high rector and Gby affinity

Question 43

GTP- alpha

Answer 43

Active ; low rector and Gby affinity

Question 44

G proteins

Answer 44

Hetrotimeric intracellular proteins with a, b, y subunits

Question 45

G alpha

Answer 45

Guanine nucleotide binding site

Question 46

Role of PKA

Answer 46

Phosphorylated fuel metabolism proteins