Drug-Receptor Interactions

Question 1

Receptor

Answer 1

a protein that is able to interact with molecules, whereby changing a cell’s physiology

Question 2

Ligand-gated receptors

Answer 2

Location: membrane

Time frame: milliseconds

Examples: nicotinic, acetylcholine

Question 3

G-protein receptor

Answer 3

Location: membrane

Time frame: seconds

Examples: muscarinic, acetylcholine

Question 4

Receptor kinase receptors

Answer 4

Location: membrane

Time frame: hours

Example: insulin

Question 5

Nuclear receptors

Answer 5

Location: nucleus

Time frame: hours

Example: steroid

Question 6

The ability of a cell to respond to a molecule is dependent upon _____?

Answer 6

whether the cell expresses the receptor that the molecule targets

Question 7

Three characteristics of receptors

Answer 7

1. they have finite lifespans
2. they undergo processes of synthesis and degradation
3. # can be affected by diseases and degree of stimulation (by exogenous or endogenous substances)

Question 8

What roles do lysosomes play in receptor modification?

Answer 8

they are acidic organelle responsible for protein degradation in the endocytic and secretory pathways

Question 9

How do proteosomes degrade proteins in a “discriminate fashion?”

Answer 9

they require a signal (e.g. ubiquitination) and typically target cytosolic or nuclear proteins

Question 10

What is the Ubiquitous Protein System?

Answer 10

seeks and destroys damaged and excessive proteins by marking targets with ubiquitin/enzyme complex acting as a death signal to proteosomes

Question 11

Receptor desensitization

Answer 11

a decline in the response to repeated or sustained application of an agonist due to changes at the level of the receptor; uncoupling b/t receptor activation and downstream effect (signaling efficiency has changed)

Question 12

Receptor downregulation

Answer 12

receptors on surface are endocytosed or degraded due to repeated stimulation by an agonist; important for tolerance (e.g. opioid tolerance)

Question 13

Tolerance

Answer 13

cellular response to repeated stimulation of a receptor is reduced; contributed to by both receptor downregulation and desensitization; is reversible

Question 14

Tachyphylaxis

Answer 14

very acute, sudden decrease in response to receptor stimulation

Question 15

Receptor upregulation

Answer 15

Increased # of receptors – can be due to enhanced synthesis or decreased degradation/internalization

Question 16

Receptor hypersensitivity

Answer 16

less stimulus is needed to produce an effect – can be due to greater signaling molecules (increased signaling efficiency)

Question 17

Agonist

Answer 17

Molecules that activate receptors; can be partial or full

Question 18

What is the mechanism of action for partial agonists?

Answer 18

they compete for the same receptor and decrease a full agonist’s activity