Module 10 - Neurotransmitters Flashcards
what are the 4 classes of receptor
Receptor Tyrosine kinase
G protein coupled receptor (metabotropic)
Ligand-gated ion channels (ionotropic)
Nuc hormone receptor
In Gprotein, where are the binding domains in Family A and C
A - binding site buried in membrane
C - binding site in N terminus
3 types of G protein
Gs
Gi
Gq
each have corresponding alpha subunits
what is the target and effect of Gs
adenylate cyclase
increases cAMP
(s for stimulatory)
what is the target and effect of Gi
adenylate cyclase
dec cAMP
(i for inhibitory)
what is the target and effect of Gq
phospholipase C
increases IP3
thus increasing Ca2+
5 monoamines
HANDS
histamine
adrenaline
noradrenaline
dopamine
serotonin
key property of monamines
made from aromatic AAs
all aromatic
REMEMBER - ACh is NOT monoamine = not aromatic
what are the groups of neurotransmitters
monoamines
amine (only ACh)
neuropeptides
amino acids
others (e.g. ATP)
what enzyme joins acetyl coA and choline to make ACh
choline acetyl transferase
byproduct of coA
what enzyme breaks down ACh and what ar the products
AChEsterase
choline + acetate
how does glutamate receptor get rid of gulatamate in the synapse
2 ways
- EAAT = reuptake in presynapse
- glutamate can diffuse into surrounding area
= taken up by astrocyte
- converts glutamate to glutamine
- which gets turned back into glutamate only in presynapse
what enzyme turns glutamate to glutamine
glutamine synthase
what enzyme turns glutamine into glutamate
glutaminase
what neurotransmitters are only metabotropic
HANDAN
Histamine
Adenosine
Noradrenaline
Dopamine
Adrenaline
Neuropeptides
what are the 2 types of ACh receptors
nicotinic
muscarinic
structure of nicotinic ACh receptors
pentameric
16 subunits (9 alpha, 4 beta, gamma (foetal), delta and epsilon (adult)
2 sites of ACh binding
structure of muscarinic ACh receptors
monomeric
M1-5 (so 5 receptors types)
1 Ach binding site
are Ach receptors excitatory or inhibitory
nicotinic - excitatory
muscarinic - excitatory or inhibitory
what are the 2 types of glutatmate receptors
ionotropic
metabotropic
what are the 3 types of ionotropic glutamate receptors
- AMPA
- Kainate
- NMDA
what type of GPCR are metabotropic gluatamate receptors
family C GPCRs
always operate as dimers
what types of metabotropic glutamate receptors are there
3 groups with 8 types
Group 1 = post synaptic, excitatory
Group 2, 3 = pre synaptic inhibitory
what is different about NMDA ionotropic glutamate receptors
vry permeable to Ca 2+
and is blocked by Mg2+ at resting
- also, needs glycine as a coagonist
what voltage needed to get rid of the Mg2+ in NMDA receptors
-30mV
which type of glutamate receptor allows increased depolarisation and transmission to soma, and how?
NMDA
but can only happen after AMPA is activated for prolonged time
also metabotropic receptor has (slow) also contributes
depolarises little by little, until -30mV
then Mg2+ removed from NMDA
what are the 2 types of GABA receptors
GABA a/c
GABA b
what type of receptor is GABA a/c
ligand gated chloride channels
pentamers
fast
what type of receptors are GABA b
family C GPCRs
(only 1 half of receptor dimer interacts with GABA)
slower
how does increase in Cl- permeability lead to inhibition
the reversal potential for Cl is vry close to RMP
so it stabilises the memb potential
harder to move the potential out of resting
what 3 things do GABA b receptors do (note that they have Gi proteins)
- inhibit Ca2+ channels
- open K+ channels
- inhibit adenylyl cyclase = less cyclicAMP
example of autoreceptors
- noradrenaline control by alpha 2 autoreceptors
(GPCRs w/Gi)
example of heteroreceptor
dopamine release stimulated by heteroreceptor
- which are nicotinic ACh receptors
what are the 2 mechanisms used by nicotinic ACh receptors to act as heteroreceptors for dopamine release
- depolarise the presyn nerve terminal
increasing the Ca2+ entry from channels - also allow Ca2+ entry through the heterreceptor itself
what is a protein regulator of the nicotinic receptors
Lynx1
what did Lynx1 evolve to become
toxins (alpha cobra toxins and alpha bungarotoxins)
targetting nicotinic ACh receptors
