Mm Exam3 Signal Transduction Ii

Front 1

how is cAMP synthezied?
from _____ in the presence of _____

Back 1

ATP
cyclic AMP

Front 2

what does Gs proteins do to adenyl cyclase?

Back 2

stimulates intracellular cAMP level

Front 3

what do Gi proteins do to adenyl cyclase?

Back 3

inhibits intracellular cAMP level

Front 4

What does cAMP activate?

Back 4

PKA causing phosphorylation of multiple proteins

Front 5

Can PKA directly activate cyclic nucleotide gated ion channels?

Back 5

yes

Front 6

how is cAMP degradaded?

Back 6

by PDE (phosphodiesterase)

Front 7

what is the mechanism of action of the PDE?

Back 7

hydroluzes the 3' cyclic phosphate bond of the cyclin nucleotide (cAMP or cGMP), producing inactive AMP or GMP

Front 8

T or F
distinct reseptor signaling pathways provide hormonal regulation by either increasing or decreasing intracellular cAMP level

Back 8

T

Front 9

what catalyze the production of cGMP?

Back 9

guanylyl cyclase

GTP --> cGMP

Front 10

what turns cGMP --> GMP

Back 10

PDE

Front 11

what activate soluble GC (guanyl cyclase)?

Back 11

NO

Front 12

what activates receptor GC?

Back 12

extracellular hormones like natriuretic peptides

Front 13

what are the two kinds of GC?

Back 13

soluble GC and receptor GC

Front 14

what does cGMP activates?

Back 14

cGMP dependent protein kinase(PKG), and cyclic nucleotide-gated (CNG) ion channels

Front 15

Does cGMP activate cyclic nucleotide gated ion channels?

Back 15

yes

Front 16

how are cyclic nucleotide gated (CNG) channel activities increased?

Back 16

by direct cyclic nucleotide binding on cytosolic side

Front 17

what do CNG (cyclic nucleotide-gated) ion channels do?

Back 17

alters cell membrane potential
major effector in visual and olfactory sensory signaling
primarily permeable to Na+ ions

Front 18

structural component of soluble GC

Back 18

heterodimers (alpha,beta) that possesses a heme prosthetic group with a ferrous (Fe2+) core that associates with His 105 of the beta subunit

Front 19

how does NO activate soluble GC?

Back 19

by directly binding to the ferrous core, breaking the bond b/w iron and histidine 105, causing activation of the GC domain and production of cGMP

Front 20

how is soluble GC terminated?

Back 20

dissociation of NO from the heme prosthetic group

Front 21

T or F
CO can also bind to the heme group of soluble GC and has exactly the same affect as NO

Back 21

F
CO does bind to the heme group of sGC, but is far less efficacious as an activator of the GC domain. It does not break the Fe-His105 bond

Front 22

cGMP-dependent protein kinase (PKG) is a member of the serine/threonine protein kinase family, what does it do?

phosphorylates multiple proteins at _____residues, altering protein activity/function.

Back 22

phosphorylates multiple proteins at Ser/Thr residues, altering protein activity/function.

Front 23

what do Gq proteins activate?

Back 23

phospholipase C beta

Front 24

what does phospholipase C beta do?

Back 24

cleaves PIP producing IP3 and DAG (diacylglycerol)

Front 25

what does IP3 does?

Back 25

release calcium from ER

Front 26

IP3 initiates release of calcium from ____

Back 26

ER

Front 27

what does diacylglycerol (DAG) do?

Back 27

activates protein kinase C with help of calcium

Front 28

when elevated calcium binds calmodulin, what's getting activated?

Back 28

CaM (Ca-calmodulin) protein kinase

Front 29

during amplification GPCR can activate multiple heterotrimeric G proteins, what do activated effector enzymes catalyze?

Back 29

productio of multiple second messengers

Front 30

what can phosphorylate multiple substrates altering their function?

Back 30

2nd messenger effector (i.e. PKA)

Front 31

what does Phospholipase C beta cleave?

Back 31

PIP (phosphatydylnositol 4,5 bisphosphate)

Front 32

what does cleaved PIP2 yield?

Back 32

2 bioactive 2nd messengers, DAG and inositol triphosphate (IP3)

Front 33

what 2nd messenger in vascular smooth muscle is being effected by Prazosin?

Back 33

prozosin's block of alpha1adrenergic receptors inhibits vascular PLC-beta activation by Gq and the production of DAG, IP3 and Ca release. since intracellular calcium triggers contraction of cascular smooth muscle, reducing intracellular Ca2+ promotes vasodilation and effectively lowers arterial blood pressure.

Front 34

what 2nd messengers are effected by common ED drugs (ie viagra) and what is their mechanism of action?

Back 34

PDE
viagra is a selective inhibitor of PDE5 which is responsible for degradation of cGMP in the corpus cavernosum. when sexual stimulation causes local release of NO, sildenafil inhibition of PDE5 causes increased levels of cGMP in the corpus cavernosum resulting in smooth muscle relaxation and inflow of blood to the corpus cavernosum

Front 35

viagra is a selective inhibitor of ____ which is responsible for degradation of cGMP in the corpus cavernosum. when sexual stimulation causes local release of NO, sildenafil inhibition of PDE5 causes increased levels of ____ in the corpus cavernosum resulting in smooth muscle ______ and inflow of blood to the corpus cavernosum

Back 35

PDE5
cGMP
relaxation

Front 36

phototransduction example
dark: high or low rate of transmitter release
Na+ channel open or close

Back 36

high rate of transmitter
Na+ channel open = depolarization

Front 37

phototransduction example
Light: high or low rate of transmitter release
Na+ channel open or closed

Back 37

low rate
Na+ channel closed - hyperpolarization

Front 38

when 1 photon hits rhodopsin, GPCR, cGMP activated.
Na+ channgel close --> hyperpolarization --> increase or decrease transmitter relase

Back 38

decrease

Front 39

match up the followings:
signal molecule, cyclic AMP, adenyl cyclase

1st messegner, Gprotein effector, 2nd messenger

Back 39

signal molecule - 1st messenger
cAMP - 2nd messenger
adenyl cyclase - G-protein effector

Front 40

In case of cholera, PKA was inhibited or activated?

Back 40

activated

Front 41

what does viagra inhibit?

Back 41

PDE5 therefore prevents cGMP degradation

Front 42

mechanism to keep cytolic Ca2+ level low:
plasma membrane CaATPase pumps and exchangers that extrude Ca2+ using _____

Back 42

ATP

Front 43

PDE can be considered _____

Back 43

G protein effector
it hydrolyzes cyclic nucleotide

Front 44

can a patient take a selective alpha 1 adrenergic receptor blocker (Gq signaling pathway) and Viagra take at the same time?

Back 44

Yes
the two drugs have different mechanisms of action and are not contraindicated

Front 45

can a patient take a generic nitrates for maintenance of high BP( which activates soluble GC and increases cGMP) and Viagra take at the same time?

Back 45

No. both use the same mechanism of action and two together can cause severe hypotension