CB17 Receptors

Question 1

Define the terms “ligand” & “receptor” as they pertain to cell signalling

Answer 1

A ligand is a molecule that binds specifically to a receptor

A receptor is a macromolecule that specifically recognises a ligand

Question 2

Name the different mechanisms for cell-cell communication within the body and the distance travelled/response time

Answer 2

Juxtacrine - direct transmission (contact dependent)

Paracrine
- general - nearby cells, um-mm, <1s
- synaptic - target cell far, 50nm, <1ms

Endocrine - systematically via circulation, cm-m, secs-mins

Autocrine - signal acts on receptors on the cell that releases it

Question 3

List the different categories of cellular receptors

Answer 3

Ligand-gated ion channels
G-protein coupled receptors
Enzyme-linked receptors

Question 4

Define KD

Answer 4

KD is the concentration of ligand at which half of the available receptors are bound

Question 5

Define EC50

Answer 5

EC50 is the concentration of ligand that produces half of the maximal response

Question 6

What is upregulation

Answer 6

Increased receptor number
Increases response
Increase the sensitivity (decrease EC50)

Question 7

What is downregulation

Answer 7

Reduced receptor number
Decreased response
Decrease sensitivity (increased EC50)

Question 8

Define the terms agonist and antagonist

Answer 8

Agonist - binding of ligand produces a response

Antagonist - produces no cell response but interferes with he action of agonist

Question 9

What is a partial agonist

Answer 9

Does not produce full maximum response