1.4 Phys cAMP, FA, IPs

Question 1

adipose tissue lipolysis is catabolic or anabolic?

Answer 1

catabolic

Question 2

the first step of adipose lipolysis to catalyzed by?

Answer 2

TAG lipase, aka hormone sensetive lipase (HSL)

Question 3

epi, norepi, glucagon and ACTH activate? how?

Answer 3

HSL via phosphorylation

Question 4

insulin inactivates?

Answer 4

strongly and rapidly inactivates HSL by dephosphorylation

Question 5

what activates HSL?

Answer 5

PKA aka protein kinase A in cAMP transduction

Question 6

What are the adrenergic receptor? what pathway are they a part of?

Answer 6

nor and epi ALPHA AR=IP3
nor and epi beta AR= cAMP
*** you are using the SAME ligand but bind different receptors

Question 7

Gs G-mediated protein transduction is always coupled with?

Answer 7

adenylate cyclase and cAMP

Question 8

what is Gi protein?

Answer 8

inhibitory protein

• completly different set of ligands and receptors
• when a specific ligand binds to a receptor that is linked to Gi, it will INHIBIT adenylate cyclase

Question 9

What are the affects of adenylate cyclase being inhibited?

Answer 9

inhibits cAMP, which inhibits protein kinase A, which inhibits phosphorylation/activation of downstream pathways

Question 10

Gi protein is an example of?

Answer 10

an endogenous way your body regulates adenylate cyclase/AMP systems

Question 11

for both Gq and Gs, its activation does what to alpha subunit?

Answer 11

replaces the GDP with GTP, thus releasing the subunit which then enters membrane and activates CE

Question 12

what is CE used in Gq?

Answer 12

phospholipase C (PL-C) =IP3

Question 13

what is CE used in Gs?

Answer 13

adenylate cyclase =cAMP

Question 14

what does PL-C use as a substrate to make products?

Answer 14

phosphatidylinosital bisphsphate (PIP2)

Question 15

where does PIP2 come from? made by?

Answer 15

inner leaflet of plasma membrane MADE BY phosphatidylinosital kinases!

Question 16

what are 2nd messengers in Gq?

Answer 16

DAG, Ca+, IP3

Question 17

what does DAG do in Gq?

Answer 17

activates protein kinase C

do NOT confuse with PKA found in Gs/cAMP

Question 18

what does IP3 do in Gq?

Answer 18

interacts with cytoplasmic reticulum, thus causing an increase in calcium

Question 19

what does most of the ca+ as a 2nd messenger do in Gq?

Answer 19

binds to calmodulin to complete the enzyme

*this activates it, causing it to phosphorylate its targets

Question 20

some proteins are linked directly to? what activates it?

Answer 20

channel proteins

*the acitvation and interaction with alpha subunit

Question 21

what is membrane signal transduction?

Answer 21

info from EXTRAcellular signal is tranmitted across the membrane
*only info crosses, activates 2nd messenger

Question 22

alpha subunit interacts with CE how?

Answer 22

by entering membrane WITH GTP

Question 23

Once active, CE does what?

Answer 23

converts a specific substrate molecule to a specific 2nd messenger

Question 24

what is the 2nd messenger produced by adenylate cyclase?

Answer 24

cAMP

Question 25

cAMP signal amplification pathway is an example of?

Answer 25

a G-mediated membrane signal transduction

Question 26

G-mediated membrane signal transduction pathways ALL consist of?

Answer 26

1) specific ligand
2) 7 transmembrane receptors
3) G-protein
4) catalytic enzyme
5) second messengers

Question 27

what converts active cAMP to AMP?

Answer 27

phosphodiesterase

Question 28

what inhibits phosphodiesterases?

Answer 28

xanthines

Question 29

examples of xanthines?

Answer 29

caffiene (coffee)
theophylline (tea)
theobiomine (chocolate)

Question 30

PKA is active when it is?

Answer 30

phosphorylated

Question 31

ligands are typically lipophobic or liprophilic?

Answer 31

lipophobic; unable to cross membrane