Study Guide chapter 2: Receptor Theory

Question 1

What are the two main types of receptors based on molecular structure?

Answer 1

Intracellular receptors and cell surface receptors

Question 2

What is the largest classification of receptors?

Answer 2

Seven transmembrane (7TM) receptors

Question 3

What type of channels respond to a change in charge on the cell membrane?

Answer 3

Volatge gated-Ion channels

Question 4

What are catalytic receptors?

Answer 4

Receptors that have enzymatic activity, membrane bound, ligand activated receptors.
Example: RTKs
*They are called “catalytic” because their binding with a ligand on the outside of the cell directly triggers a catalytic activity—meaning they initiate a chemical reaction on the inside of the cell.

Question 5

Draw the RTK pathway

Answer 5

Question 6

Describe the cell signaling process.

Answer 6

The receptor converts an external signal into an internal effect

Question 7

What is a signal transduction cascade?

Answer 7

A sequence of events where a signaling molecule activates a receptor, which activates downstream proteins

Question 8

What is phosphorylation?

Answer 8

The addition of a phosphate group (PO4-) to a protein, often activating it

Question 9

Draw the Phosphorylation cascade

Answer 9

Question 10

What is a protein kinase?

Answer 10

An enzyme class that attaches a phosphate group to another protein

Question 11

Name four transmembrane signaling methods by which drug-receptor interactions exert their effects.

Answer 11

• Ligand gated Ion Channel
• Catalytic
• GPCRs
• Voltage gated ion channels

Question 12

What characterizes GPCRs?

Answer 12

They have a receptor and a G-Protein coupled together.
1st part is the receptor, 2nd part is the G-Protein.

Question 13

What happens when a ligand binds to a GPCR?

Answer 13

The GPCR undergoes a conformational change and activates the G-Protein

Question 14

What are the components of a trimeric G-Protein?

Answer 14

• Alpha
• Beta
• Gamma

Question 15

Draw out the GPCR

Answer 15

*Note the exterior portion has a NH3+
and the G-protein interaction portion has a COO- that is not shown

Question 16

Describe the role of second messengers.

Answer 16

Small chemicals that amplify the signal and activate other proteins, and enzymes to illicit an effect.

Question 17

List the most common second messengers.

Answer 17

• cAMP
• IP3

Question 18

Draw out the second messenger pathway

Answer 18

Question 19

What is desensitization in terms of GPCR signaling?

Answer 19

A decrease in response over time due to receptor shut down

Question 20

Draw the process of desensitization

Answer 20

Question 21

Differentiate ligand gated and voltage gated ion channels.

Answer 21

• Ligand gated: opens upon ligand binding (opens in response to binding)
• Voltage gated: opens in response to a change in voltage (opens in respose to change in charge around the cell) i.e. Na+, K+, Ca2+

Question 22

What types of ligands can bind to receptors inside the cell?

Answer 22

• Gases (Nitric oxide)
• Lipid soluble agents (steroids)

Question 23

What are ionotropic channels?

Answer 23

Ligand-gated ion channels where the receptor and ligand are the same
Ex: nACh-R (nicotinic acetylcholine) needs ACh to bind in order to open the channel

Question 24

Describe the nACh receptor binding process

Answer 24

*Has 2 active sites.
*Signal molecule binds the active site, the receptor itself is the channel, so when ligand binds, the channel opens and the ions flow from higher concerntration to lower concentration. Will stay open until the ligand is no longer present

Question 25

What are metabotropic channels?

Answer 25

GPCR + ion channel

Question 26

Define Kinase and Phosphatase

Answer 26

Kinase adds a phosphate group Phosphatase strips a phosphate group