Receptor Theory Flashcards
Name the four receptor types
- receptors
- Enzymes
- Transport/carriers
- Ion channels
Where would you find receptors and what binds to them
Proteins found on the plasma membrane or intracellularly that recognise and respond to an endogenous ligand
What is a small molecule
Molecules that come in tablet form
What is a biological
A peptide that has been engineered to interact with drug binding proteins
What are the four receptor families and their characteristics
- Ligand gated ion channel - 4TMDs - Extracellular ligand binding site on the N-terminus
- GPCR - 7TMDS - Ligand binding sites can be outside (peptides) or inside a pocket created by the transmembrane domains (Small molecules) - Signalling is transduced by G proteins - Alpha subunit exchanges its GDP for GTP and dissociates from the beta and gamma subunits - this causes signal transduction - turned off with dephosphorylation - subunits come back together
- Kinase linked receptor - 1TMD - All kinase linked ligands are peptides - Binding site on outside of the cell on the amino terminus - kinase domains phosphorylate proteins
- Nuclear receptor - No TMDs - Found within the cytosol - DNA binding domain - control of transcription
What are the units of affinity
Molarity (M)
What does affinity describe
How well the drug will physically and chemically interact with the receptor
How is affinity measured
As a ratio of the forward and backward binding reactions
What is Ka
k+1/k-1
What is Kd
k-1/k+1
How is high affinity achieved in terms of Ka and Kd
If Ka is high and Kd is low then affinity will be high
What does it mean to have low Kd
The molecules are more likely to remain together
What is efficacy
The likeliness of a drug receptor complex to illicit a response in the cell
How is efficacy measured
1-0
What is occupancy
Total number of receptors occupied/Total number of receptors
