Acetylcholine Flashcards
what is the only common feature between nicotinic and muscarinic ACh receptors
the amino acid sequence of the ACh binding site
what is the structure of muscarinic ACh receptors
single polypeptide, 7 transmembrane domains
are muscarinic ACh receptors ion channels or G protein coupled receptors
G protein coupled receptors
what are the precursors and enzyme used in ACh synthesis
choline, acetyl CoA, cholineacetyltransferase
how is ACh taken up into vesicles
through a vesicular ACh transporter
how is ACh removed from the synaptic cleft
1) diffuses away
2) broken down by acetylcholinesterase into acetate and choline
acetate feeds into Kreb’s cycle
choline taken up through choline transporter
are nicotinic ACh receptors ligand gated cation channels or g protein couple receptors
ligand gated cation channels
how many subunits are nAChR formed of
5
what are the 2 most common combination of subunits of nAChR in the CNS
1) 2 alpha4, 3 beta2
2) 5 alpha7
which has a higher sensitivity to ACh?
alpha4 (2), beta2 (3)
which ions channel closes faster after ACh binding
Alpha7 homopentamer
how many mols of calcium does each channel let in for every sodium ion
alpha7 homopentamer - 10
other - 1
where is the a7 homopentamer found in the CNS
hippocampus, cortex
where is the 2 alpha4, 3 beta2 channel found in the CNS
thalamus, cortex
how many types of muscarinic receptors are there
5
varenicline is a partial agonist to which type of nAChR. what is the drug used to treat
those containing a4 subunits. used to treat nicotine dependance
name two AChesterase inhibitors
Galantamine, rivastigmine
nicotine causes release of which neurotransmitter
Dopamine
nicotine downregulates expression of nAChRs. true or false
false. it upregulates expression of nAChRs
name two examples of muscarinic antagonists. what are they usually used to treat
benztropine, biperiden. early stages parkinson’s
give an example of a nAChR channelopathy
autosomal dominant nocturnal frontal lobe epilepsy
what gene is mutated in ADNFLE? what are the consequences on protein structure
gene coding for alpha4 subunit in nAChR 2 alpha4, 3 beta2. causes 2nd transmembrane domain (of 4) to change
what are the consequences of a mutated 2nd transmembrane domain in an alpha subunit of a 2 alpha4, 3 beta2?
causes inhibition of Calcium channels on presynaptic terminals of GABA neurons.
ca entry inhibited - less release of GABA which is inhibitory
less inhibition - hyperexcitation
