Seven transmembrane domain receptors

Question 1

Examples of seven-transmembrane domain receptors

Answer 1

• Beta androgenic receptor
• alpha androgenic receptor
• muscarinic cholinergic receptor
• VIP (vasoactive intestinal polypeptide (important for front part of the eye) and angiotensin II both affect blood vessels
• 5HT (Serotonin)
• DA (dopamine)
• SP (pain receptor and neurotransmitter in the spinal cord)
• Leutinizing hormone, folicle stimulating hormone, and thyroid stimulating hormone.
• Rhodopsin
• Platelet activating factor

Question 2

Where on the receptor are binding sites for signaling molecules located?

Answer 2

Within the extracellular loops. This is also a great target for drugs and can influence the ability of the G protein to produce a result.

Question 3

Internal loops are associate with what

Answer 3

The g-protein, microtubules, and cytoskeletal structures.

Question 4

What happens when the first messenger binds to its receptor?

Answer 4

Intracellular calcium levels increase. Ca2+ is the second messenger and can enter through the membrane via Ca2+ channels or it can be released from the ER. (Calcium cannot be free in the cytosol because it can cause excitotoxicity- cell dies from over working itself).

Question 5

An example of a cytotoxic disease, one where calcium is free in the cytosol and causes excitotoxicity.

Answer 5

ALS

Question 6

Proteins that bind Ca2+

Answer 6

Calmodulin, calreticulin, and paravalbumin.

Question 7

What is the role of a second messenger inside the cell

Answer 7

Modifies the signal, like a pansy scheme in reverse. (AKA it amplifies)
This is a slower ionotropic mechanism, but has a much wider effect with a low amount of stimulus.

Question 8

Calsequesterin

Answer 8

Brings Ca2+ in and out (sequesters and isolates the calcium)

Question 9

When Ca2+ is released from the ER, it is typically mediated by

Answer 9

IP3

Question 10

4 alpha G-protein subunit types and their role when activated by GTP (Transducers)

Answer 10

Gs- adenylyl cyclase stimulation (increase CAMP)
Gi/o- adenylyl cyclase inhibitor (ion channels inhibitor CAMP phospholipase)
Gq- Phospholipase C activation. (increase DAG and IP3)
G1- Transducin cGMP phosphodiesterase found in the rod outer segment (activates Rho)

Question 11

Kinase that can autophosphorylate itself

Answer 11

Tyrosine kinase can add a phosphate to itself or other tyrosine residues.

Question 12

What does an activated protein kinase do?

Answer 12

Add Phosphates to serine or threonine residues to mobilize Ca2+

Question 13

Protein kinases can be dependent on

Answer 13

CAMP, cGMP, PKc, calmodulin

Question 14

Structure of tyrosine kinase

Answer 14

Exists as a single unit molecule (inactive monomers), but when it becomes a dimer, it can add phosphate groups to serine or threonine residues on molecules. Can mobilize Ca2+ and bring proteins to itself.

Question 15

Inactive and active tyrosine kinase

Answer 15

Inactive- monomers not together

active- when phosphorylated, 2 monomers will form a dimer.

Question 16

4 second messengers

Answer 16

cAMP, IP3, Arachindonic Acid (AA), and DAG

Question 17

Requirements for a first messenger

Answer 17

Must be external

Question 18

Calcium can be considered 2 things in a cascasde

Answer 18

Second messenger and a secondary effector

Question 19

cAMP system-

1. External signal
2. Receptor it binds
3. Transducer
4. Primary effector
5. Second messenger
6. Secondary effector

Answer 19

1. NE
2. B-adrenergic receptor
3. Alpha subunit is Gs, which means it acts to increase cAMP.
4. Adenlylyl cyclase
5. cAMP
6. cAMP dependent protein kinase (PKA)

Question 20

Phosphoionsitol system

1. External signal
2. Receptor it binds
3. Transducer
4. Primary effector
5. Second messenger
6. Secondary effector

Answer 20

1. ACh
2. Muscarinic ACh receptor
3. Go (same Gi) ion channel inhibitor of cAMP phospholipases
4. phospholipase C
5. IP3 is created from PIP2 and goes to the ER to release calcium stores. Ca2+ activates DAG, which activates PKC.
6. Ca2+ release from ER due to IP3 and Protein Kinase C activated by DAG

Question 21

Arachinodic acid system

1. External signal
2. Receptor it binds
3. Transducer
4. Primary effector
5. Second messenger
6. Secondary effector

Answer 21

1. Histamine
2. Histamine receptor
3. Go/i, which is an ion channel inhibitor of cAMP phospholipase
4. Phospholipase A2
5. Arachidonic acid
6. 5 lipoxygenase, 12 lipoxygenase, and cyclooxyrgenase

Question 22

cAMP pathway. PKA activation causes phosphorylation of ___

Answer 22

CREBP, cAMP response element binding protein, which modifies DNA.

Question 23

What is adenylyl cycalse

Answer 23

An integral membrane bound enzyme that synthesizes cAMP when stimulated

Question 24

IP3 is made by the hydrolysis of _____ and by which enzyme

Answer 24

PIP2, a phospholipid that is located in the plasma membrane by phospholipase C.

Question 25

Calmodulin can bind to how many molecules of calcium?

Answer 25

4. Discovered at St. Jude.

Question 26

Rho

Answer 26

A type of GTPase that reorganizes the cytoskeleton through serine or threonine protein kinases

Question 27

Eicosinoids are made where and derived from what by what enzyme

Answer 27

Made in the plasma membrane, derived from arachidonic acid by PLA2 (phospholipase A2)

Question 28

Cyclooxygenase pathway (AA)

Answer 28

Produces prostaglandins, which have vascular and inflammation actions. Activates smooth muscle and regulates blood flow locally. Produces thromboxjnes, which assist with blood clotting and other vascular actions.

Question 29

Lipooxygenase pathway (AA)

Answer 29

Produces leukotrienes, which mediate allergic and inflammatory reactions.

Question 30

Role of prostaglandins

Answer 30

Activates smooth muscle and regulates blood flow locally. Has vascular and inflammation actions Produced through the cyclo-oxygenase pathway.

Question 31

Structure and role of leukotrienes

Answer 31

Has 3 conjugate double bonds. Involved with vascular contraction and permeability regulators. Mediates allergic and inflammatory response. Activated through the lipo-oxygenase pathway.

Question 32

NSAIDS and COX inhibits which AA pathway

Answer 32

Inhibits the cyclo-oxygense pathway, inhibiting the production of prostaglandins and thromboxjnes, both which play a role in blood clotting/blood flow and inflammation.