L3 - Receptors 1 Flashcards
what are the 4 types of receptors
ligand-gated ion channels
G-protein coupled receptors
Kinase-linked receptors
nuclear receptors
what do kinase-linked receptors do and how long does it take
protein phosphorylation and it takes hours
what do nuclear receptors do and how long does it take
gene transcription and it takes hours
what do ligand-gated ion channels do
they direct the flow of ions across a membrane
which kind of ion channel has been studied the most
nicotinic acetylcholine
where can you find NA receptors in the body
in muscles (contraction) and neurons (firing)
what is the general structure of a NA receptor
5 subunits in a ring imbedded into the plasma membrane
what is the structure of the subunits
protein chains going through the membrane (M1-M4)
What does M2 do
it has a kink that acts as a gate for stopping flow
what kind of amino acids is M2 made out of
AA with bulky hydrophobic side chains
near the top of the channel what kind of amino acids are found
negative amino acids are found there to attract Na+
what is the ligand for the NA receptor
it is Acetylcholine
acetylcholine binds to ________ subunits
opposite
binding allows for the pore to become
bigger allowing ions in
what is the mechanism of activation
- Ach binding
- small subunit rotation
- M2 moves outward
why are the amino acids on the channel negative
to be anchored to the hydrophobic tails of the membrane
where is the N-binding terminus of the NA receptor
it is extracellular
what are some other ligand-gated ion channels
GABAa receptor channel
5-HT3 (serotonin)
glycine receptor channel
what is a fun fact about the 5-HT3 receptor
it is found in the vomit center of the brain
what is different about the GABAa receptor compared to the NA receptor
GABAa has a positive pore because it is trying to attract Cl-
What are some antagonist for nicotinic acetylecholine
tubocurarine: blocks receptors and competes with Ach - paralysis
atracurium: like tubocurarine but used clinically - local anesthesia
alpha-bungarotoxin: block pore channel flow - cobra venom
what are some antagonist for GABAa receptors
picrotoxin: fishberry - binds and block channel flow
what are some agonists for NA receptors
nicotine: opens it
what are some agonists for the GABAa receptor
Benzodiazepines: binds and enhances action (relaxes and stop brain activity)
muscimol: hallucinogen mushroom (binds and opens GABAa)
