G-Protein Coupled Receptors

Question 1

All of the following are examples of second messengers EXCEPT:

Answer 1

Study on!!!

Question 2

When organizing all of this in your head, it is helpful to think of the following sequence of events.

Once you understand this, you can use it as a scaffold to understand each of the GPCR systems in greater detail

First Messenger >>>

Answer 2

>>> G-Protein Coupled Receptor (GPCR)

Question 3

G-Protein Coupled Receptor >>>

Answer 3

>>> Effector

Question 4

Effector >>>

Answer 4

>>> Second Messenger

Question 5

Second Messenger >>>

Answer 5

>>> Cellular Response

Question 6

The —– is a ligand that binds to the GPCR

Answer 6

First messenger

Question 7

The First messenger is a ligand that binds to the GPCR. This ligand could be something —– to the body or something —– to the body

Answer 7

endogenous

or

exogenous

Question 8

—– or —– are endogenous First messengers

Answer 8

Neurotransmitters or Hormones

Question 9

—– are exogenous First messengers

Answer 9

Drugs

Question 10

The —– portion of the GPCR is accessible outside of the cell membrane

Answer 10

receptor portion

Question 11

The G-protein itself resides —– of the cell membrane

Answer 11

inside

Question 12

The GPCR consists of 3 subunits:

Answer 12

alpha, beta, and gamma

Question 13

The G-protein either stimulates or inhibits an —–.

Answer 13

effector

Question 14

The G-protein either stimulates or inhibits an effector. This effector can be an —– or an —–.

Answer 14

enzyme or an ion channel

Question 15

—– and —– are G stimulatory proteins

Answer 15

Gs and Gq

Question 16

G stimulatory proteins (Gs and Gq) —– an effector.

Answer 16

turn on

Question 17

—– is a G inhibitory protein

Answer 17

Gi

Question 18

G inhibitory proteins (Gi) —– an effector.

Answer 18

turn off

Question 19

When a ligand binds to the GPCR, the

ligand-receptor interaction —– the G-protein

Answer 19

activates the G-protein

Question 20

When a ligand binds to the GPCR, the ligand-receptor interaction activates the G-protein. This causes the —– subunit to dissociate from the —– and —– subunits

Answer 20

alpha subunit

beta and gamma subunits

Question 21

The alpha subunit of a Gs or Gq protein will —– an effector,

Answer 21

turn on

Question 22

The alpha subunit of a Gi protein will —– an effector

Answer 22

turn off

Question 23

When the ligand unbinds from the receptor, the alpha subunit —– the beta and gamma subunits, and its interaction with the effector ends

Answer 23

rejoins

Question 24

The function of the effector is to activate the —–.

Answer 24

second messenger

Question 25

Enzymatic effectors include ----- and -----.

Answer 25

**Adenylate cyclase**, and ## Footnote **Phospholipase C**

Question 26

Ion channel effectors include ----- and -----.

Answer 26

**GABA-A,** and **M2 receptor** at the SA node

Question 27

The second messenger modulates a network of ----- activity

Answer 27

**enzymatic** activity

Question 28

The second messenger modulates a network of enzymatic activity, including ----- and -----.

Answer 28

**Phosphatases** and **Protein kinases**

Question 29

The second messenger modulates a network of enzymatic activity, including phosphatases and protein kinases. This governs a complex series of ----- reactions

Answer 29

**intracellular** reactions

Question 30

The second messenger modulates a network of enzymatic activity, including phosphatases and protein kinases. This governs a complex series of intracellular reactions that elicit a ----- response

Answer 30

**specific** response

Question 31

The second messenger modulates a network of enzymatic activity, including phosphatases and protein kinases. This governs a complex series of intracellular reactions that elicit a specific response within a particular -----.

Answer 31

**cell type**

Question 32

Second messenger systems allow for signal -----.

Answer 32

**amplification**

Question 33

Which process allows a single molecule to initiate a process that activates a large number of physiologic changes

Answer 33

**Signal amplification**

Question 34

Second messenger systems allow for **signal amplification**. This process allows a single molecule to initiate a process that activates a large number of physiologic changes - each step progressively increases the ----- of the response

Answer 34

**magnitude**

Question 35

The intracellular response to a second messenger is ----- specific.

Answer 35

**tissue-**specific

Question 36

The intracellular response to a second messenger is **tissue specific**. For example, increased cAMP may cause ----- effects in ----- cell types.

Answer 36

**different** effects in **different** cell types.

Question 37

There are 5 second messengers that you should know:

Answer 37

1. Cyclic adenosine monophosphate (**cAMP**) 2. Cyclic guanosine monophosphate (**cGMP**) 3. Inositol triphosphate (**IP3**) 4. Diacylglycerol (**DAG**) 5. Calcium ion (**Ca+2**)

Question 38

All of the following are examples of second messengers **EXCEPT:**

Answer 38

*Glutamate* Glutamate is the first messenger for the NMDA receptor

Question 39

----- are extracellular chemicals (neurotransmitters, hormones, or drugs) that stimulate a receptor

Answer 39

**First messengers**

Question 40

----- are intracellular chemicals (usually enzymes) that instruct the cell to do something

Answer 40

**Second messengers**

Question 41

*_References:_*

Answer 41

* Hall. Guyton* & *Hall's Textbook of Medical Physiology 12th ed.2011. p. 549* & *886-888.* * Hemmings. Pharmacology and Physiology for Anesthesia: Foundations and Clinical Application. 1st ed. 2013. p. 13**,* *254-255* & *398.*