Signal Transduction

Question 1

_____ bind with receptors that also act as ion channels or they interact with G-proteins to stimulate effector enzymes to produce “second messengers”

Answer 1

NTs

Question 2

Most ____ receptors interact with G-proteins to alter “second messenger” levels

Answer 2

hormone

Question 3

____ hormone receptors are cytosolic receptors which travel to the nucleus to alter mRNA synthesis

Answer 3

steroid

Question 4

Most ___ ____ receptors have intrinsic tyrosine kinase activity and cause phosphorylation of tyrosine residues on specific proteins

Answer 4

growth factor

Question 5

In regards to being excitatory and inhibitory, give the difference between catecholamines and indolamines.

Answer 5

catecholamines: excitatory
indolamines: inhibitory

Question 6

Epi is a catecholamine. Give its associated peptide, AA, and other characteristic

Answer 6

peptide: nueropeptide y
AA: glutamate
other: ATP

Question 7

NE is a catecholamine. Give its associated peptide, AA, and other characteristic

Answer 7

peptide: enkephalins
AA: aspartate
other: zinc

Question 8

Dopamine is a catecholamine. Give its associated peptide and other characteristic

Answer 8

peptide: somatostatin
other: arachidonic acid

Question 9

Serotonin and Histamine are both indolamines. Give their associated AAs

Answer 9

serotonin: gamma-Aminobutyric acid
histamine: glycine

Question 10

In regards to G-protein cycling, occupation of the receptor protein causes it to associate with what?

Answer 10

the G-protein

Question 11

In regards to G-protein cycling, the receptor/G-protein complex allows a ___ to displace a ____ from the alpha-subunit

Answer 11

GTP; GDP

Question 12

In regards to G-protein cycling, binding of GTP causes dissociation into what?

Answer 12

free alpha-subunit and free beta/gamma subunit

Question 13

In regards to G-protein cycling, the alpha-subunit interacts with an effector protein to produce ___ ____ or occasionally open ____ channels

Answer 13

second messengers; ion

Question 14

In regards to G-protein cycling, the alpha-subunit has intrinsic ____ activity, so the attached GTP is turned into GDP. This inactivates the alpha-subunit and causes it to rebind the beta/gamma subunit

Answer 14

GTPase

Question 15

cAMP is made by membrane spanning enzymes called ____ ____

Answer 15

adenylate cyclase

note: an ATP-Mg2+ complex is the substrate and free Mg2+ is a necessary cofactor

Question 16

The cAMP that is formed activates what?

Answer 16

protein kinase A

Question 17

______ break down cAMP and terminate its activity

Answer 17

phosphodiesterases

Question 18

Phospholipase C is a membrane bound enzyme that converts ____ into ____ and ____

Answer 18

PIP2; IP3; DAG

Question 19

Phospholipase C is activated when a receptor-ligand complex activates a G-protein of the ___ gamily

Answer 19

Gq

Question 20

The IP3 formed at the plasma membrane binds to receptors on the _____ _____ and causes release of intracellular ___ stores

Answer 20

Endoplasmic Retiuclum; Ca2+

Question 21

DAG remains membrane associated. Protein kinase __ translocates from the cytosol to the membrane to become activated by DAG

Answer 21

C

note: activated PKC phosphorylates proteins and alters their functions

Question 22

Membrane bound ____ cycles appears to be directly coupled to receptors and forms of cGMP from GTP when receptors become occupied

Answer 22

guanylate

Question 23

____ is formed when the AA arginine is broken down

Answer 23

NO

note: enzyme is Nitric Oxide synthetase

Question 24

NO synthetase is activated by what?

Answer 24

Ca/calodulin complex

Question 25

NO exerts its effect by activating a soluble, cytosolic type of guanylate cyclase, thus increasing ____

Answer 25

cGMP

Question 26

NO is a unique second messenger. Why?

Answer 26

it is membrane soluble - allows it to diffuse to nearby cells and increase cGMP levels in those cells as well. Such a phenomena occurs between vascular endothelial cells and nearby smooth muscle cells

Question 27

cGMP exerts its effect in a variety of ways. Describe.

Answer 27

direct binding to ion channels; activating cGMP-dependent protein kinase

Question 28

____ break down cGMP and terminate its action

Answer 28

phosphodiesterase

Question 29

____ is a NT in both the CNS and PNS. It binds to Nicotinic and muscarinic receptors

Answer 29

acetylcholine

Question 30

____ receptors are composed of various combinations of 5 subunits. The subunits are arranged to form a central cavity that extends across the membrane

Answer 30

nicotinic

Question 31

The core of the nicotinic receptor protein is normally too small for ion passage. When Ach binds the receptor, what happens?

Answer 31

alpha-subunit (which recognizes receptor) causes conformation change which allow cations to cross the membrane through the central core

Question 32

Nicotinic receptors on skeletal muscle have different alpha and beta subunits than nicotinic receptors on autonomic ganglia. True or false?

Answer 32

true

Question 33

Ligand gated channels for other NTs like GABA, glycine, 5-HT and glutamate have structural and sequence similarity to ____ receptors

Answer 33

nicotinic

Question 34

_____ receptors are not channels despite being activated by Ach. These receptors operate through G-proteins to alter the activity of a number of second messenger systems

Answer 34

muscarinic

Question 35

In regards to muscarinic receptors, m1, m3, and m5 appear to activate what?

Answer 35

PLC through Gq

Question 36

In regards to muscarinic receptors, m2 and m4 inhibit what?

Answer 36

couple through Gi to inhibit adenylate cyclase

Question 37

All _____ receptors are coupled through G-proteins

Answer 37

adrenergic

Question 38

In regards to adrenergic receptors, occupation of Beta-receptors stimulates what?

Answer 38

adenylate cyclase to produce cAMP and activate PKA

Question 39

In regards to adrenergic receptors, occupation of alpha1-receptors increases and activates what?

Answer 39

increases IP3 and DAG and activates Ca2+ channels note: involves PLC activation

Question 40

In regards to adrenergic receptors, occupation of alpha2-receptors leads to inhibition of what?

Answer 40

adenylate cyclase note: effects are probably Gi-mediated